StringUtils (Apache Commons Lang 3.12.0 API)

java.lang.Object
- org.apache.commons.lang3.StringUtils

```
public class StringUtils
extends Object
```
Operations on String that are null safe.
- IsEmpty/IsBlank - checks if a String contains text
- Trim/Strip - removes leading and trailing whitespace
- Equals/Compare - compares two strings in a null-safe manner
- startsWith - check if a String starts with a prefix in a null-safe manner
- endsWith - check if a String ends with a suffix in a null-safe manner
- IndexOf/LastIndexOf/Contains - null-safe index-of checks
- IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
- ContainsOnly/ContainsNone/ContainsAny - checks if String contains only/none/any of these characters
- Substring/Left/Right/Mid - null-safe substring extractions
- SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
- Split/Join - splits a String into an array of substrings and vice versa
- Remove/Delete - removes part of a String
- Replace/Overlay - Searches a String and replaces one String with another
- Chomp/Chop - removes the last part of a String
- AppendIfMissing - appends a suffix to the end of the String if not present
- PrependIfMissing - prepends a prefix to the start of the String if not present
- LeftPad/RightPad/Center/Repeat - pads a String
- UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
- CountMatches - counts the number of occurrences of one String in another
- IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
- DefaultString - protects against a null input String
- Rotate - rotate (circular shift) a String
- Reverse/ReverseDelimited - reverses a String
- Abbreviate - abbreviates a string using ellipses or another given String
- Difference - compares Strings and reports on their differences
- LevenshteinDistance - the number of changes needed to change one String into another
The StringUtils class defines certain words related to String handling.
- null - null
- empty - a zero-length string ("")
- space - the space character (' ', char 32)
- whitespace - the characters defined by Character.isWhitespace(char)
- trim - the characters <= 32 as in String.trim()
StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils.

Methods in this class include sample code in their Javadoc comments to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#
Since:

1.0

See Also:

String

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`CR` A String for carriage return CR ("\r").
`static String`	`EMPTY` The empty String `""`.
`static int`	`INDEX_NOT_FOUND` Represents a failed index search.
`static String`	`LF` A String for linefeed LF ("\n").
`static String`	`SPACE` A String for a space character.

Constructor Summary

Constructors
Constructor and Description

StringUtils()
StringUtils instances should NOT be constructed in standard programming.

Constructors
Constructor and Description
`StringUtils()` `StringUtils` instances should NOT be constructed in standard programming.

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static String`	`abbreviate(String str, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviate(String str, int offset, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviate(String str, String abbrevMarker, int maxWidth)` Abbreviates a String using another given String as replacement marker.
`static String`	`abbreviate(String str, String abbrevMarker, int offset, int maxWidth)` Abbreviates a String using a given replacement marker.
`static String`	`abbreviateMiddle(String str, String middle, int length)` Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.
`static String`	`appendIfMissing(String str, CharSequence suffix, CharSequence... suffixes)` Appends the suffix to the end of the string if the string does not already end with any of the suffixes.
`static String`	`appendIfMissingIgnoreCase(String str, CharSequence suffix, CharSequence... suffixes)` Appends the suffix to the end of the string if the string does not already end, case insensitive, with any of the suffixes.
`static String`	`capitalize(String str)` Capitalizes a String changing the first character to title case as per `Character.toTitleCase(int)`.
`static String`	`center(String str, int size)` Centers a String in a larger String of size `size` using the space character (' ').
`static String`	`center(String str, int size, char padChar)` Centers a String in a larger String of size `size`.
`static String`	`center(String str, int size, String padStr)` Centers a String in a larger String of size `size`.
`static String`	`chomp(String str)` Removes one newline from end of a String if it's there, otherwise leave it alone.
`static String`	`chomp(String str, String separator)` Deprecated. This feature will be removed in Lang 4.0, use `removeEnd(String, String)` instead
`static String`	`chop(String str)` Remove the last character from a String.
`static int`	`compare(String str1, String str2)` Compare two Strings lexicographically, as per `String.compareTo(String)`, returning :
`static int`	`compare(String str1, String str2, boolean nullIsLess)` Compare two Strings lexicographically, as per `String.compareTo(String)`, returning :
`static int`	`compareIgnoreCase(String str1, String str2)` Compare two Strings lexicographically, ignoring case differences, as per `String.compareToIgnoreCase(String)`, returning :
`static int`	`compareIgnoreCase(String str1, String str2, boolean nullIsLess)` Compare two Strings lexicographically, ignoring case differences, as per `String.compareToIgnoreCase(String)`, returning :
`static boolean`	`contains(CharSequence seq, CharSequence searchSeq)` Checks if CharSequence contains a search CharSequence, handling `null`.
`static boolean`	`contains(CharSequence seq, int searchChar)` Checks if CharSequence contains a search character, handling `null`.
`static boolean`	`containsAny(CharSequence cs, char... searchChars)` Checks if the CharSequence contains any character in the given set of characters.
`static boolean`	`containsAny(CharSequence cs, CharSequence... searchCharSequences)` Checks if the CharSequence contains any of the CharSequences in the given array.
`static boolean`	`containsAny(CharSequence cs, CharSequence searchChars)` Checks if the CharSequence contains any character in the given set of characters.
`static boolean`	`containsAnyIgnoreCase(CharSequence cs, CharSequence... searchCharSequences)` Checks if the CharSequence contains any of the CharSequences in the given array, ignoring case.
`static boolean`	`containsIgnoreCase(CharSequence str, CharSequence searchStr)` Checks if CharSequence contains a search CharSequence irrespective of case, handling `null`.
`static boolean`	`containsNone(CharSequence cs, char... searchChars)` Checks that the CharSequence does not contain certain characters.
`static boolean`	`containsNone(CharSequence cs, String invalidChars)` Checks that the CharSequence does not contain certain characters.
`static boolean`	`containsOnly(CharSequence cs, char... valid)` Checks if the CharSequence contains only certain characters.
`static boolean`	`containsOnly(CharSequence cs, String validChars)` Checks if the CharSequence contains only certain characters.
`static boolean`	`containsWhitespace(CharSequence seq)` Check whether the given CharSequence contains any whitespace characters.
`static int`	`countMatches(CharSequence str, char ch)` Counts how many times the char appears in the given string.
`static int`	`countMatches(CharSequence str, CharSequence sub)` Counts how many times the substring appears in the larger string.
`static <T extends CharSequence> T`	`defaultIfBlank(T str, T defaultStr)` Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or `null`, the value of `defaultStr`.
`static <T extends CharSequence> T`	`defaultIfEmpty(T str, T defaultStr)` Returns either the passed in CharSequence, or if the CharSequence is empty or `null`, the value of `defaultStr`.
`static String`	`defaultString(String str)` Returns either the passed in String, or if the String is `null`, an empty String ("").
`static String`	`defaultString(String str, String defaultStr)` Returns either the passed in String, or if the String is `null`, the value of `defaultStr`.
`static String`	`deleteWhitespace(String str)` Deletes all whitespaces from a String as defined by `Character.isWhitespace(char)`.
`static String`	`difference(String str1, String str2)` Compares two Strings, and returns the portion where they differ.
`static boolean`	`endsWith(CharSequence str, CharSequence suffix)` Check if a CharSequence ends with a specified suffix.
`static boolean`	`endsWithAny(CharSequence sequence, CharSequence... searchStrings)` Check if a CharSequence ends with any of the provided case-sensitive suffixes.
`static boolean`	`endsWithIgnoreCase(CharSequence str, CharSequence suffix)` Case insensitive check if a CharSequence ends with a specified suffix.
`static boolean`	`equals(CharSequence cs1, CharSequence cs2)` Compares two CharSequences, returning `true` if they represent equal sequences of characters.
`static boolean`	`equalsAny(CharSequence string, CharSequence... searchStrings)` Compares given `string` to a CharSequences vararg of `searchStrings`, returning `true` if the `string` is equal to any of the `searchStrings`.
`static boolean`	`equalsAnyIgnoreCase(CharSequence string, CharSequence... searchStrings)` Compares given `string` to a CharSequences vararg of `searchStrings`, returning `true` if the `string` is equal to any of the `searchStrings`, ignoring case.
`static boolean`	`equalsIgnoreCase(CharSequence cs1, CharSequence cs2)` Compares two CharSequences, returning `true` if they represent equal sequences of characters, ignoring case.
`static <T extends CharSequence> T`	`firstNonBlank(T... values)` Returns the first value in the array which is not empty (""), `null` or whitespace only.
`static <T extends CharSequence> T`	`firstNonEmpty(T... values)` Returns the first value in the array which is not empty.
`static byte[]`	`getBytes(String string, Charset charset)` Calls `String.getBytes(Charset)` in a null-safe manner.
`static byte[]`	`getBytes(String string, String charset)` Calls `String.getBytes(String)` in a null-safe manner.
`static String`	`getCommonPrefix(String... strs)` Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.
`static String`	`getDigits(String str)` Checks if a String `str` contains Unicode digits, if yes then concatenate all the digits in `str` and return it as a String.
`static int`	`getFuzzyDistance(CharSequence term, CharSequence query, Locale locale)` Deprecated. as of 3.6, use commons-text FuzzyScore instead
`static <T extends CharSequence> T`	`getIfBlank(T str, Supplier<T> defaultSupplier)` Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or `null`, the value supplied by `defaultStrSupplier`.
`static <T extends CharSequence> T`	`getIfEmpty(T str, Supplier<T> defaultSupplier)` Returns either the passed in CharSequence, or if the CharSequence is empty or `null`, the value supplied by `defaultStrSupplier`.
`static double`	`getJaroWinklerDistance(CharSequence first, CharSequence second)` Deprecated. as of 3.6, use commons-text JaroWinklerDistance instead
`static int`	`getLevenshteinDistance(CharSequence s, CharSequence t)` Deprecated. as of 3.6, use commons-text LevenshteinDistance instead
`static int`	`getLevenshteinDistance(CharSequence s, CharSequence t, int threshold)` Deprecated. as of 3.6, use commons-text LevenshteinDistance instead
`static int`	`indexOf(CharSequence seq, CharSequence searchSeq)` Finds the first index within a CharSequence, handling `null`.
`static int`	`indexOf(CharSequence seq, CharSequence searchSeq, int startPos)` Finds the first index within a CharSequence, handling `null`.
`static int`	`indexOf(CharSequence seq, int searchChar)` Returns the index within `seq` of the first occurrence of the specified character.
`static int`	`indexOf(CharSequence seq, int searchChar, int startPos)` Returns the index within `seq` of the first occurrence of the specified character, starting the search at the specified index.
`static int`	`indexOfAny(CharSequence cs, char... searchChars)` Search a CharSequence to find the first index of any character in the given set of characters.
`static int`	`indexOfAny(CharSequence str, CharSequence... searchStrs)` Find the first index of any of a set of potential substrings.
`static int`	`indexOfAny(CharSequence cs, String searchChars)` Search a CharSequence to find the first index of any character in the given set of characters.
`static int`	`indexOfAnyBut(CharSequence cs, char... searchChars)` Searches a CharSequence to find the first index of any character not in the given set of characters.
`static int`	`indexOfAnyBut(CharSequence seq, CharSequence searchChars)` Search a CharSequence to find the first index of any character not in the given set of characters.
`static int`	`indexOfDifference(CharSequence... css)` Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.
`static int`	`indexOfDifference(CharSequence cs1, CharSequence cs2)` Compares two CharSequences, and returns the index at which the CharSequences begin to differ.
`static int`	`indexOfIgnoreCase(CharSequence str, CharSequence searchStr)` Case in-sensitive find of the first index within a CharSequence.
`static int`	`indexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)` Case in-sensitive find of the first index within a CharSequence from the specified position.
`static boolean`	`isAllBlank(CharSequence... css)` Checks if all of the CharSequences are empty (""), null or whitespace only.
`static boolean`	`isAllEmpty(CharSequence... css)` Checks if all of the CharSequences are empty ("") or null.
`static boolean`	`isAllLowerCase(CharSequence cs)` Checks if the CharSequence contains only lowercase characters.
`static boolean`	`isAllUpperCase(CharSequence cs)` Checks if the CharSequence contains only uppercase characters.
`static boolean`	`isAlpha(CharSequence cs)` Checks if the CharSequence contains only Unicode letters.
`static boolean`	`isAlphanumeric(CharSequence cs)` Checks if the CharSequence contains only Unicode letters or digits.
`static boolean`	`isAlphanumericSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode letters, digits or space (`' '`).
`static boolean`	`isAlphaSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode letters and space (' ').
`static boolean`	`isAnyBlank(CharSequence... css)` Checks if any of the CharSequences are empty ("") or null or whitespace only.
`static boolean`	`isAnyEmpty(CharSequence... css)` Checks if any of the CharSequences are empty ("") or null.
`static boolean`	`isAsciiPrintable(CharSequence cs)` Checks if the CharSequence contains only ASCII printable characters.
`static boolean`	`isBlank(CharSequence cs)` Checks if a CharSequence is empty (""), null or whitespace only.
`static boolean`	`isEmpty(CharSequence cs)` Checks if a CharSequence is empty ("") or null.
`static boolean`	`isMixedCase(CharSequence cs)` Checks if the CharSequence contains mixed casing of both uppercase and lowercase characters.
`static boolean`	`isNoneBlank(CharSequence... css)` Checks if none of the CharSequences are empty (""), null or whitespace only.
`static boolean`	`isNoneEmpty(CharSequence... css)` Checks if none of the CharSequences are empty ("") or null.
`static boolean`	`isNotBlank(CharSequence cs)` Checks if a CharSequence is not empty (""), not null and not whitespace only.
`static boolean`	`isNotEmpty(CharSequence cs)` Checks if a CharSequence is not empty ("") and not null.
`static boolean`	`isNumeric(CharSequence cs)` Checks if the CharSequence contains only Unicode digits.
`static boolean`	`isNumericSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode digits or space (`' '`).
`static boolean`	`isWhitespace(CharSequence cs)` Checks if the CharSequence contains only whitespace.
`static String`	`join(boolean[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(boolean[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(byte[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(byte[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(char[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(char[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(double[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(double[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(float[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(float[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(int[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(int[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Iterable<?> iterable, char separator)` Joins the elements of the provided `Iterable` into a single String containing the provided elements.
`static String`	`join(Iterable<?> iterable, String separator)` Joins the elements of the provided `Iterable` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, char separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, String separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(List<?> list, char separator, int startIndex, int endIndex)` Joins the elements of the provided `List` into a single String containing the provided list of elements.
`static String`	`join(List<?> list, String separator, int startIndex, int endIndex)` Joins the elements of the provided `List` into a single String containing the provided list of elements.
`static String`	`join(long[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(long[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(short[] array, char delimiter)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(short[] array, char delimiter, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static <T> String`	`join(T... elements)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`joinWith(String delimiter, Object... array)` Joins the elements of the provided varargs into a single String containing the provided elements.
`static int`	`lastIndexOf(CharSequence seq, CharSequence searchSeq)` Finds the last index within a CharSequence, handling `null`.
`static int`	`lastIndexOf(CharSequence seq, CharSequence searchSeq, int startPos)` Finds the last index within a CharSequence, handling `null`.
`static int`	`lastIndexOf(CharSequence seq, int searchChar)` Returns the index within `seq` of the last occurrence of the specified character.
`static int`	`lastIndexOf(CharSequence seq, int searchChar, int startPos)` Returns the index within `seq` of the last occurrence of the specified character, searching backward starting at the specified index.
`static int`	`lastIndexOfAny(CharSequence str, CharSequence... searchStrs)` Find the latest index of any substring in a set of potential substrings.
`static int`	`lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr)` Case in-sensitive find of the last index within a CharSequence.
`static int`	`lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)` Case in-sensitive find of the last index within a CharSequence from the specified position.
`static int`	`lastOrdinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)` Finds the n-th last index within a String, handling `null`.
`static String`	`left(String str, int len)` Gets the leftmost `len` characters of a String.
`static String`	`leftPad(String str, int size)` Left pad a String with spaces (' ').
`static String`	`leftPad(String str, int size, char padChar)` Left pad a String with a specified character.
`static String`	`leftPad(String str, int size, String padStr)` Left pad a String with a specified String.
`static int`	`length(CharSequence cs)` Gets a CharSequence length or `0` if the CharSequence is `null`.
`static String`	`lowerCase(String str)` Converts a String to lower case as per `String.toLowerCase()`.
`static String`	`lowerCase(String str, Locale locale)` Converts a String to lower case as per `String.toLowerCase(Locale)`.
`static String`	`mid(String str, int pos, int len)` Gets `len` characters from the middle of a String.
`static String`	`normalizeSpace(String str)` Similar to http://www.w3.org/TR/xpath/#function-normalize -space
`static int`	`ordinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)` Finds the n-th index within a CharSequence, handling `null`.
`static String`	`overlay(String str, String overlay, int start, int end)` Overlays part of a String with another String.
`static String`	`prependIfMissing(String str, CharSequence prefix, CharSequence... prefixes)` Prepends the prefix to the start of the string if the string does not already start with any of the prefixes.
`static String`	`prependIfMissingIgnoreCase(String str, CharSequence prefix, CharSequence... prefixes)` Prepends the prefix to the start of the string if the string does not already start, case insensitive, with any of the prefixes.
`static String`	`remove(String str, char remove)` Removes all occurrences of a character from within the source string.
`static String`	`remove(String str, String remove)` Removes all occurrences of a substring from within the source string.
`static String`	`removeAll(String text, String regex)` Deprecated. Moved to RegExUtils.
`static String`	`removeEnd(String str, String remove)` Removes a substring only if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeEndIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeFirst(String text, String regex)` Deprecated. Moved to RegExUtils.
`static String`	`removeIgnoreCase(String str, String remove)` Case insensitive removal of all occurrences of a substring from within the source string.
`static String`	`removePattern(String source, String regex)` Deprecated. Moved to RegExUtils.
`static String`	`removeStart(String str, String remove)` Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.
`static String`	`removeStartIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.
`static String`	`repeat(char ch, int repeat)` Returns padding using the specified delimiter repeated to a given length.
`static String`	`repeat(String str, int repeat)` Repeat a String `repeat` times to form a new String.
`static String`	`repeat(String str, String separator, int repeat)` Repeat a String `repeat` times to form a new String, with a String separator injected each time.
`static String`	`replace(String text, String searchString, String replacement)` Replaces all occurrences of a String within another String.
`static String`	`replace(String text, String searchString, String replacement, int max)` Replaces a String with another String inside a larger String, for the first `max` values of the search String.
`static String`	`replaceAll(String text, String regex, String replacement)` Deprecated. Moved to RegExUtils.
`static String`	`replaceChars(String str, char searchChar, char replaceChar)` Replaces all occurrences of a character in a String with another.
`static String`	`replaceChars(String str, String searchChars, String replaceChars)` Replaces multiple characters in a String in one go.
`static String`	`replaceEach(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceEachRepeatedly(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceFirst(String text, String regex, String replacement)` Deprecated. Moved to RegExUtils.
`static String`	`replaceIgnoreCase(String text, String searchString, String replacement)` Case insensitively replaces all occurrences of a String within another String.
`static String`	`replaceIgnoreCase(String text, String searchString, String replacement, int max)` Case insensitively replaces a String with another String inside a larger String, for the first `max` values of the search String.
`static String`	`replaceOnce(String text, String searchString, String replacement)` Replaces a String with another String inside a larger String, once.
`static String`	`replaceOnceIgnoreCase(String text, String searchString, String replacement)` Case insensitively replaces a String with another String inside a larger String, once.
`static String`	`replacePattern(String source, String regex, String replacement)` Deprecated. Moved to RegExUtils.
`static String`	`reverse(String str)` Reverses a String as per `StringBuilder.reverse()`.
`static String`	`reverseDelimited(String str, char separatorChar)` Reverses a String that is delimited by a specific character.
`static String`	`right(String str, int len)` Gets the rightmost `len` characters of a String.
`static String`	`rightPad(String str, int size)` Right pad a String with spaces (' ').
`static String`	`rightPad(String str, int size, char padChar)` Right pad a String with a specified character.
`static String`	`rightPad(String str, int size, String padStr)` Right pad a String with a specified String.
`static String`	`rotate(String str, int shift)` Rotate (circular shift) a String of `shift` characters.
`static String[]`	`split(String str)` Splits the provided text into an array, using whitespace as the separator.
`static String[]`	`split(String str, char separatorChar)` Splits the provided text into an array, separator specified.
`static String[]`	`split(String str, String separatorChars)` Splits the provided text into an array, separators specified.
`static String[]`	`split(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified.
`static String[]`	`splitByCharacterType(String str)` Splits a String by Character type as returned by `java.lang.Character.getType(char)`.
`static String[]`	`splitByCharacterTypeCamelCase(String str)` Splits a String by Character type as returned by `java.lang.Character.getType(char)`.
`static String[]`	`splitByWholeSeparator(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparator(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitPreserveAllTokens(String str)` Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, char separatorChar)` Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars)` Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static boolean`	`startsWith(CharSequence str, CharSequence prefix)` Check if a CharSequence starts with a specified prefix.
`static boolean`	`startsWithAny(CharSequence sequence, CharSequence... searchStrings)` Check if a CharSequence starts with any of the provided case-sensitive prefixes.
`static boolean`	`startsWithIgnoreCase(CharSequence str, CharSequence prefix)` Case insensitive check if a CharSequence starts with a specified prefix.
`static String`	`strip(String str)` Strips whitespace from the start and end of a String.
`static String`	`strip(String str, String stripChars)` Strips any of a set of characters from the start and end of a String.
`static String`	`stripAccents(String input)` Removes diacritics (~= accents) from a string.
`static String[]`	`stripAll(String... strs)` Strips whitespace from the start and end of every String in an array.
`static String[]`	`stripAll(String[] strs, String stripChars)` Strips any of a set of characters from the start and end of every String in an array.
`static String`	`stripEnd(String str, String stripChars)` Strips any of a set of characters from the end of a String.
`static String`	`stripStart(String str, String stripChars)` Strips any of a set of characters from the start of a String.
`static String`	`stripToEmpty(String str)` Strips whitespace from the start and end of a String returning an empty String if `null` input.
`static String`	`stripToNull(String str)` Strips whitespace from the start and end of a String returning `null` if the String is empty ("") after the strip.
`static String`	`substring(String str, int start)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substring(String str, int start, int end)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substringAfter(String str, int separator)` Gets the substring after the first occurrence of a separator.
`static String`	`substringAfter(String str, String separator)` Gets the substring after the first occurrence of a separator.
`static String`	`substringAfterLast(String str, int separator)` Gets the substring after the last occurrence of a separator.
`static String`	`substringAfterLast(String str, String separator)` Gets the substring after the last occurrence of a separator.
`static String`	`substringBefore(String str, int separator)` Gets the substring before the first occurrence of a separator.
`static String`	`substringBefore(String str, String separator)` Gets the substring before the first occurrence of a separator.
`static String`	`substringBeforeLast(String str, String separator)` Gets the substring before the last occurrence of a separator.
`static String`	`substringBetween(String str, String tag)` Gets the String that is nested in between two instances of the same String.
`static String`	`substringBetween(String str, String open, String close)` Gets the String that is nested in between two Strings.
`static String[]`	`substringsBetween(String str, String open, String close)` Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.
`static String`	`swapCase(String str)` Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.
`static int[]`	`toCodePoints(CharSequence cs)` Converts a `CharSequence` into an array of code points.
`static String`	`toEncodedString(byte[] bytes, Charset charset)` Converts a `byte[]` to a String using the specified character encoding.
`static String`	`toRootLowerCase(String source)` Converts the given source String as a lower-case using the `Locale.ROOT` locale in a null-safe manner.
`static String`	`toRootUpperCase(String source)` Converts the given source String as a upper-case using the `Locale.ROOT` locale in a null-safe manner.
`static String`	`toString(byte[] bytes, String charsetName)` Deprecated. use `toEncodedString(byte[], Charset)` instead of String constants in your code
`static String`	`trim(String str)` Removes control characters (char <= 32) from both ends of this String, handling `null` by returning `null`.
`static String`	`trimToEmpty(String str)` Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is `null`.
`static String`	`trimToNull(String str)` Removes control characters (char <= 32) from both ends of this String returning `null` if the String is empty ("") after the trim or if it is `null`.
`static String`	`truncate(String str, int maxWidth)` Truncates a String.
`static String`	`truncate(String str, int offset, int maxWidth)` Truncates a String.
`static String`	`uncapitalize(String str)` Uncapitalizes a String, changing the first character to lower case as per `Character.toLowerCase(int)`.
`static String`	`unwrap(String str, char wrapChar)` Unwraps a given string from a character.
`static String`	`unwrap(String str, String wrapToken)` Unwraps a given string from anther string.
`static String`	`upperCase(String str)` Converts a String to upper case as per `String.toUpperCase()`.
`static String`	`upperCase(String str, Locale locale)` Converts a String to upper case as per `String.toUpperCase(Locale)`.
`static String`	`valueOf(char[] value)` Returns the string representation of the `char` array or null.
`static String`	`wrap(String str, char wrapWith)` Wraps a string with a char.
`static String`	`wrap(String str, String wrapWith)` Wraps a String with another String.
`static String`	`wrapIfMissing(String str, char wrapWith)` Wraps a string with a char if that char is missing from the start or end of the given string.
`static String`	`wrapIfMissing(String str, String wrapWith)` Wraps a string with a string if that string is missing from the start or end of the given string.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- SPACE
```
public static final String SPACE
```
  A String for a space character.
  
  Since:
  
  3.2
  
  See Also:
  
  Constant Field Values
- EMPTY
```
public static final String EMPTY
```
  The empty String "".
  
  Since:
  
  2.0
  
  See Also:
  
  Constant Field Values
- LF
```
public static final String LF
```
  A String for linefeed LF ("\n").
  
  Since:
  
  3.2
  
  See Also:
  
  JLF: Escape Sequences for Character and String Literals, Constant Field Values
- CR
```
public static final String CR
```
  A String for carriage return CR ("\r").
  
  Since:
  
  3.2
  
  See Also:
  
  JLF: Escape Sequences for Character and String Literals, Constant Field Values
- INDEX_NOT_FOUND
```
public static final int INDEX_NOT_FOUND
```
  Represents a failed index search.
  
  Since:
  
  2.1
  
  See Also:
  
  Constant Field Values

Constructor Detail
- StringUtils
```
public StringUtils()
```
  StringUtils instances should NOT be constructed in standard programming. Instead, the class should be used as StringUtils.trim(" foo ");.
  
  This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

abbreviate
```
public static String abbreviate(String str,
                                int maxWidth)
```
Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."

Specifically:
- If the number of characters in str is less than or equal to maxWidth, return str.
- Else abbreviate it to (substring(str, 0, max-3) + "...").
- If maxWidth is less than 4, throw an IllegalArgumentException.
- In no case will it return a String of length greater than maxWidth.
```
 StringUtils.abbreviate(null, *)      = null
 StringUtils.abbreviate("", 4)        = ""
 StringUtils.abbreviate("abcdefg", 6) = "abc..."
 StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 4) = "a..."
 StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
 
```
Parameters:

str - the String to check, may be null

maxWidth - maximum length of result String, must be at least 4

Returns:

abbreviated String, null if null String input

Throws:

IllegalArgumentException - if the width is too small

Since:

2.0

abbreviate

public static String abbreviate(String str,
                                int offset,
                                int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."

Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.

In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *, *)                = null
 StringUtils.abbreviate("", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
 StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException

Parameters:: str - the String to check, may be null; offset - left edge of source String; maxWidth - maximum length of result String, must be at least 4
Returns:: abbreviated String, null if null String input
Throws:: IllegalArgumentException - if the width is too small
Since:: 2.0

abbreviate
```
public static String abbreviate(String str,
                                String abbrevMarker,
                                int maxWidth)
```
Abbreviates a String using another given String as replacement marker. This will turn "Now is the time for all good men" into "Now is the time for..." if "..." was defined as the replacement marker.

Specifically:
- If the number of characters in str is less than or equal to maxWidth, return str.
- Else abbreviate it to (substring(str, 0, max-abbrevMarker.length) + abbrevMarker).
- If maxWidth is less than abbrevMarker.length + 1, throw an IllegalArgumentException.
- In no case will it return a String of length greater than maxWidth.
```
 StringUtils.abbreviate(null, "...", *)      = null
 StringUtils.abbreviate("abcdefg", null, *)  = "abcdefg"
 StringUtils.abbreviate("", "...", 4)        = ""
 StringUtils.abbreviate("abcdefg", ".", 5)   = "abcd."
 StringUtils.abbreviate("abcdefg", ".", 7)   = "abcdefg"
 StringUtils.abbreviate("abcdefg", ".", 8)   = "abcdefg"
 StringUtils.abbreviate("abcdefg", "..", 4)  = "ab.."
 StringUtils.abbreviate("abcdefg", "..", 3)  = "a.."
 StringUtils.abbreviate("abcdefg", "..", 2)  = IllegalArgumentException
 StringUtils.abbreviate("abcdefg", "...", 3) = IllegalArgumentException
 
```
Parameters:

str - the String to check, may be null

abbrevMarker - the String used as replacement marker

maxWidth - maximum length of result String, must be at least abbrevMarker.length + 1

Returns:

abbreviated String, null if null String input

Throws:

IllegalArgumentException - if the width is too small

Since:

3.6

abbreviate

public static String abbreviate(String str,
                                String abbrevMarker,
                                int offset,
                                int maxWidth)

Abbreviates a String using a given replacement marker. This will turn "Now is the time for all good men" into "...is the time for..." if "..." was defined as the replacement marker.

Works like abbreviate(String, String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the replacement marker, but it will appear somewhere in the result.

In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, null, *, *)                 = null
 StringUtils.abbreviate("abcdefghijklmno", null, *, *)    = "abcdefghijklmno"
 StringUtils.abbreviate("", "...", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", "---", -1, 10) = "abcdefg---"
 StringUtils.abbreviate("abcdefghijklmno", ",", 0, 10)    = "abcdefghi,"
 StringUtils.abbreviate("abcdefghijklmno", ",", 1, 10)    = "abcdefghi,"
 StringUtils.abbreviate("abcdefghijklmno", ",", 2, 10)    = "abcdefghi,"
 StringUtils.abbreviate("abcdefghijklmno", "::", 4, 10)   = "::efghij::"
 StringUtils.abbreviate("abcdefghijklmno", "...", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", "*", 9, 10)    = "*ghijklmno"
 StringUtils.abbreviate("abcdefghijklmno", "'", 10, 10)   = "'ghijklmno"
 StringUtils.abbreviate("abcdefghijklmno", "!", 12, 10)   = "!ghijklmno"
 StringUtils.abbreviate("abcdefghij", "abra", 0, 4)       = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", "...", 5, 6)        = IllegalArgumentException

Parameters:: str - the String to check, may be null; abbrevMarker - the String used as replacement marker; offset - left edge of source String; maxWidth - maximum length of result String, must be at least 4
Returns:: abbreviated String, null if null String input
Throws:: IllegalArgumentException - if the width is too small
Since:: 3.6

abbreviateMiddle
```
public static String abbreviateMiddle(String str,
                                      String middle,
                                      int length)
```
Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.

This abbreviation only occurs if the following criteria is met:
- Neither the String for abbreviation nor the replacement String are null or empty
- The length to truncate to is less than the length of the supplied String
- The length to truncate to is greater than 0
- The abbreviated String will have enough room for the length supplied replacement String and the first and last characters of the supplied String for abbreviation
Otherwise, the returned String will be the same as the supplied String for abbreviation.
```
 StringUtils.abbreviateMiddle(null, null, 0)      = null
 StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
 StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"
 
```
Parameters:

str - the String to abbreviate, may be null

middle - the String to replace the middle characters with, may be null

length - the length to abbreviate str to.

Returns:

the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.

Since:

2.5

appendIfMissing

public static String appendIfMissing(String str,
                                     CharSequence suffix,
                                     CharSequence... suffixes)

Appends the suffix to the end of the string if the string does not already end with any of the suffixes.

 StringUtils.appendIfMissing(null, null) = null
 StringUtils.appendIfMissing("abc", null) = "abc"
 StringUtils.appendIfMissing("", "xyz") = "xyz"
 StringUtils.appendIfMissing("abc", "xyz") = "abcxyz"
 StringUtils.appendIfMissing("abcxyz", "xyz") = "abcxyz"
 StringUtils.appendIfMissing("abcXYZ", "xyz") = "abcXYZxyz"

With additional suffixes,

 StringUtils.appendIfMissing(null, null, null) = null
 StringUtils.appendIfMissing("abc", null, null) = "abc"
 StringUtils.appendIfMissing("", "xyz", null) = "xyz"
 StringUtils.appendIfMissing("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
 StringUtils.appendIfMissing("abc", "xyz", "") = "abc"
 StringUtils.appendIfMissing("abc", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissing("abcxyz", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissing("abcmno", "xyz", "mno") = "abcmno"
 StringUtils.appendIfMissing("abcXYZ", "xyz", "mno") = "abcXYZxyz"
 StringUtils.appendIfMissing("abcMNO", "xyz", "mno") = "abcMNOxyz"

Parameters:: str - The string.; suffix - The suffix to append to the end of the string.; suffixes - Additional suffixes that are valid terminators.
Returns:: A new String if suffix was appended, the same string otherwise.
Since:: 3.2

appendIfMissingIgnoreCase

public static String appendIfMissingIgnoreCase(String str,
                                               CharSequence suffix,
                                               CharSequence... suffixes)

Appends the suffix to the end of the string if the string does not already end, case insensitive, with any of the suffixes.

 StringUtils.appendIfMissingIgnoreCase(null, null) = null
 StringUtils.appendIfMissingIgnoreCase("abc", null) = "abc"
 StringUtils.appendIfMissingIgnoreCase("", "xyz") = "xyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz") = "abcXYZ"

With additional suffixes,

 StringUtils.appendIfMissingIgnoreCase(null, null, null) = null
 StringUtils.appendIfMissingIgnoreCase("abc", null, null) = "abc"
 StringUtils.appendIfMissingIgnoreCase("", "xyz", null) = "xyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "") = "abc"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcmno", "xyz", "mno") = "abcmno"
 StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz", "mno") = "abcXYZ"
 StringUtils.appendIfMissingIgnoreCase("abcMNO", "xyz", "mno") = "abcMNO"

Parameters:: str - The string.; suffix - The suffix to append to the end of the string.; suffixes - Additional suffixes that are valid terminators.
Returns:: A new String if suffix was appended, the same string otherwise.
Since:: 3.2

capitalize
```
public static String capitalize(String str)
```
Capitalizes a String changing the first character to title case as per Character.toTitleCase(int). No other characters are changed.

For a word based algorithm, see WordUtils.capitalize(String). A null input String returns null.
```
 StringUtils.capitalize(null)  = null
 StringUtils.capitalize("")    = ""
 StringUtils.capitalize("cat") = "Cat"
 StringUtils.capitalize("cAt") = "CAt"
 StringUtils.capitalize("'cat'") = "'cat'"
 
```
Parameters:

str - the String to capitalize, may be null

Returns:

the capitalized String, null if null String input

Since:

2.0

See Also:

WordUtils.capitalize(String), uncapitalize(String)

center
```
public static String center(String str,
                            int size)
```
Centers a String in a larger String of size size using the space character (' ').

If the size is less than the String length, the original String is returned. A null String returns null. A negative size is treated as zero.

Equivalent to center(str, size, " ").
```
 StringUtils.center(null, *)   = null
 StringUtils.center("", 4)     = "    "
 StringUtils.center("ab", -1)  = "ab"
 StringUtils.center("ab", 4)   = " ab "
 StringUtils.center("abcd", 2) = "abcd"
 StringUtils.center("a", 4)    = " a  "
 
```
Parameters:

str - the String to center, may be null

size - the int size of new String, negative treated as zero

Returns:

centered String, null if null String input

center
```
public static String center(String str,
                            int size,
                            char padChar)
```
Centers a String in a larger String of size size. Uses a supplied character as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.
```
 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, ' ')     = "    "
 StringUtils.center("ab", -1, ' ')  = "ab"
 StringUtils.center("ab", 4, ' ')   = " ab "
 StringUtils.center("abcd", 2, ' ') = "abcd"
 StringUtils.center("a", 4, ' ')    = " a  "
 StringUtils.center("a", 4, 'y')    = "yayy"
 
```
Parameters:

str - the String to center, may be null

size - the int size of new String, negative treated as zero

padChar - the character to pad the new String with

Returns:

centered String, null if null String input

Since:

2.0

center

public static String center(String str,
                            int size,
                            String padStr)

Centers a String in a larger String of size size. Uses a supplied String as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, " ")     = "    "
 StringUtils.center("ab", -1, " ")  = "ab"
 StringUtils.center("ab", 4, " ")   = " ab "
 StringUtils.center("abcd", 2, " ") = "abcd"
 StringUtils.center("a", 4, " ")    = " a  "
 StringUtils.center("a", 4, "yz")   = "yayz"
 StringUtils.center("abc", 7, null) = "  abc  "
 StringUtils.center("abc", 7, "")   = "  abc  "

Parameters:: str - the String to center, may be null; size - the int size of new String, negative treated as zero; padStr - the String to pad the new String with, must not be null or empty
Returns:: centered String, null if null String input
Throws:: IllegalArgumentException - if padStr is null or empty

chomp

public static String chomp(String str)

Removes one newline from end of a String if it's there, otherwise leave it alone. A newline is "\n", "\r", or "\r\n".

NOTE: This method changed in 2.0. It now more closely matches Perl chomp.

 StringUtils.chomp(null)          = null
 StringUtils.chomp("")            = ""
 StringUtils.chomp("abc \r")      = "abc "
 StringUtils.chomp("abc\n")       = "abc"
 StringUtils.chomp("abc\r\n")     = "abc"
 StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
 StringUtils.chomp("abc\n\r")     = "abc\n"
 StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
 StringUtils.chomp("\r")          = ""
 StringUtils.chomp("\n")          = ""
 StringUtils.chomp("\r\n")        = ""

Parameters:: str - the String to chomp a newline from, may be null
Returns:: String without newline, null if null String input

chomp

@Deprecated
public static String chomp(String str,
                                       String separator)

Deprecated. This feature will be removed in Lang 4.0, use removeEnd(String, String) instead

Removes separator from the end of str if it's there, otherwise leave it alone.

NOTE: This method changed in version 2.0. It now more closely matches Perl chomp. For the previous behavior, use substringBeforeLast(String, String). This method uses String.endsWith(String).

 StringUtils.chomp(null, *)         = null
 StringUtils.chomp("", *)           = ""
 StringUtils.chomp("foobar", "bar") = "foo"
 StringUtils.chomp("foobar", "baz") = "foobar"
 StringUtils.chomp("foo", "foo")    = ""
 StringUtils.chomp("foo ", "foo")   = "foo "
 StringUtils.chomp(" foo", "foo")   = " "
 StringUtils.chomp("foo", "foooo")  = "foo"
 StringUtils.chomp("foo", "")       = "foo"
 StringUtils.chomp("foo", null)     = "foo"

Parameters:: str - the String to chomp from, may be null; separator - separator String, may be null
Returns:: String without trailing separator, null if null String input

chop

public static String chop(String str)

Remove the last character from a String.

If the String ends in \r\n, then remove both of them.

 StringUtils.chop(null)          = null
 StringUtils.chop("")            = ""
 StringUtils.chop("abc \r")      = "abc "
 StringUtils.chop("abc\n")       = "abc"
 StringUtils.chop("abc\r\n")     = "abc"
 StringUtils.chop("abc")         = "ab"
 StringUtils.chop("abc\nabc")    = "abc\nab"
 StringUtils.chop("a")           = ""
 StringUtils.chop("\r")          = ""
 StringUtils.chop("\n")          = ""
 StringUtils.chop("\r\n")        = ""

Parameters:: str - the String to chop last character from, may be null
Returns:: String without last character, null if null String input

compare
```
public static int compare(String str1,
                          String str2)
```
Compare two Strings lexicographically, as per String.compareTo(String), returning :
- int = 0, if str1 is equal to str2 (or both null)
- int < 0, if str1 is less than str2
- int > 0, if str1 is greater than str2
This is a null safe version of :
```
str1.compareTo(str2)
```
null value is considered less than non-null value. Two null references are considered equal.
```
 StringUtils.compare(null, null)   = 0
 StringUtils.compare(null , "a")   < 0
 StringUtils.compare("a", null)    > 0
 StringUtils.compare("abc", "abc") = 0
 StringUtils.compare("a", "b")     < 0
 StringUtils.compare("b", "a")     > 0
 StringUtils.compare("a", "B")     > 0
 StringUtils.compare("ab", "abc")  < 0
 
```
Parameters:

str1 - the String to compare from

str2 - the String to compare to

Returns:

< 0, 0, > 0, if str1 is respectively less, equal or greater than str2

Since:

3.5

See Also:

compare(String, String, boolean), String.compareTo(String)

compare

public static int compare(String str1,
                          String str2,
                          boolean nullIsLess)

Compare two Strings lexicographically, as per String.compareTo(String), returning :

int = 0, if str1 is equal to str2 (or both null)
int < 0, if str1 is less than str2
int > 0, if str1 is greater than str2

This is a null safe version of :

str1.compareTo(str2)

null inputs are handled according to the nullIsLess parameter. Two null references are considered equal.

 StringUtils.compare(null, null, *)     = 0
 StringUtils.compare(null , "a", true)  < 0
 StringUtils.compare(null , "a", false) > 0
 StringUtils.compare("a", null, true)   > 0
 StringUtils.compare("a", null, false)  < 0
 StringUtils.compare("abc", "abc", *)   = 0
 StringUtils.compare("a", "b", *)       < 0
 StringUtils.compare("b", "a", *)       > 0
 StringUtils.compare("a", "B", *)       > 0
 StringUtils.compare("ab", "abc", *)    < 0

Parameters:: str1 - the String to compare from; str2 - the String to compare to; nullIsLess - whether consider null value less than non-null value
Returns:: < 0, 0, > 0, if str1 is respectively less, equal ou greater than str2
Since:: 3.5
See Also:: String.compareTo(String)

compareIgnoreCase
```
public static int compareIgnoreCase(String str1,
                                    String str2)
```
Compare two Strings lexicographically, ignoring case differences, as per String.compareToIgnoreCase(String), returning :
- int = 0, if str1 is equal to str2 (or both null)
- int < 0, if str1 is less than str2
- int > 0, if str1 is greater than str2
This is a null safe version of :
```
str1.compareToIgnoreCase(str2)
```
null value is considered less than non-null value. Two null references are considered equal. Comparison is case insensitive.
```
 StringUtils.compareIgnoreCase(null, null)   = 0
 StringUtils.compareIgnoreCase(null , "a")   < 0
 StringUtils.compareIgnoreCase("a", null)    > 0
 StringUtils.compareIgnoreCase("abc", "abc") = 0
 StringUtils.compareIgnoreCase("abc", "ABC") = 0
 StringUtils.compareIgnoreCase("a", "b")     < 0
 StringUtils.compareIgnoreCase("b", "a")     > 0
 StringUtils.compareIgnoreCase("a", "B")     < 0
 StringUtils.compareIgnoreCase("A", "b")     < 0
 StringUtils.compareIgnoreCase("ab", "ABC")  < 0
 
```
Parameters:

str1 - the String to compare from

str2 - the String to compare to

Returns:

< 0, 0, > 0, if str1 is respectively less, equal ou greater than str2, ignoring case differences.

Since:

3.5

See Also:

compareIgnoreCase(String, String, boolean), String.compareToIgnoreCase(String)

compareIgnoreCase

public static int compareIgnoreCase(String str1,
                                    String str2,
                                    boolean nullIsLess)

Compare two Strings lexicographically, ignoring case differences, as per String.compareToIgnoreCase(String), returning :

int = 0, if str1 is equal to str2 (or both null)
int < 0, if str1 is less than str2
int > 0, if str1 is greater than str2

This is a null safe version of :

str1.compareToIgnoreCase(str2)

null inputs are handled according to the nullIsLess parameter. Two null references are considered equal. Comparison is case insensitive.

 StringUtils.compareIgnoreCase(null, null, *)     = 0
 StringUtils.compareIgnoreCase(null , "a", true)  < 0
 StringUtils.compareIgnoreCase(null , "a", false) > 0
 StringUtils.compareIgnoreCase("a", null, true)   > 0
 StringUtils.compareIgnoreCase("a", null, false)  < 0
 StringUtils.compareIgnoreCase("abc", "abc", *)   = 0
 StringUtils.compareIgnoreCase("abc", "ABC", *)   = 0
 StringUtils.compareIgnoreCase("a", "b", *)       < 0
 StringUtils.compareIgnoreCase("b", "a", *)       > 0
 StringUtils.compareIgnoreCase("a", "B", *)       < 0
 StringUtils.compareIgnoreCase("A", "b", *)       < 0
 StringUtils.compareIgnoreCase("ab", "abc", *)    < 0

Parameters:: str1 - the String to compare from; str2 - the String to compare to; nullIsLess - whether consider null value less than non-null value
Returns:: < 0, 0, > 0, if str1 is respectively less, equal ou greater than str2, ignoring case differences.
Since:: 3.5
See Also:: String.compareToIgnoreCase(String)

contains
```
public static boolean contains(CharSequence seq,
                               CharSequence searchSeq)
```
Checks if CharSequence contains a search CharSequence, handling null. This method uses String.indexOf(String) if possible.

A null CharSequence will return false.
```
 StringUtils.contains(null, *)     = false
 StringUtils.contains(*, null)     = false
 StringUtils.contains("", "")      = true
 StringUtils.contains("abc", "")   = true
 StringUtils.contains("abc", "a")  = true
 StringUtils.contains("abc", "z")  = false
 
```
Parameters:

seq - the CharSequence to check, may be null

searchSeq - the CharSequence to find, may be null

Returns:

true if the CharSequence contains the search CharSequence, false if not or null string input

Since:

2.0, 3.0 Changed signature from contains(String, String) to contains(CharSequence, CharSequence)

contains
```
public static boolean contains(CharSequence seq,
                               int searchChar)
```
Checks if CharSequence contains a search character, handling null. This method uses String.indexOf(int) if possible.

A null or empty ("") CharSequence will return false.
```
 StringUtils.contains(null, *)    = false
 StringUtils.contains("", *)      = false
 StringUtils.contains("abc", 'a') = true
 StringUtils.contains("abc", 'z') = false
 
```
Parameters:

seq - the CharSequence to check, may be null

searchChar - the character to find

Returns:

true if the CharSequence contains the search character, false if not or null string input

Since:

2.0, 3.0 Changed signature from contains(String, int) to contains(CharSequence, int)

containsAny

public static boolean containsAny(CharSequence cs,
                                  char... searchChars)

Checks if the CharSequence contains any character in the given set of characters.

A null CharSequence will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)                  = false
 StringUtils.containsAny("", *)                    = false
 StringUtils.containsAny(*, null)                  = false
 StringUtils.containsAny(*, [])                    = false
 StringUtils.containsAny("zzabyycdxx", ['z', 'a']) = true
 StringUtils.containsAny("zzabyycdxx", ['b', 'y']) = true
 StringUtils.containsAny("zzabyycdxx", ['z', 'y']) = true
 StringUtils.containsAny("aba", ['z'])             = false

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4, 3.0 Changed signature from containsAny(String, char[]) to containsAny(CharSequence, char...)

containsAny

public static boolean containsAny(CharSequence cs,
                                  CharSequence searchChars)

Checks if the CharSequence contains any character in the given set of characters.

A null CharSequence will return false. A null search CharSequence will return false.

 StringUtils.containsAny(null, *)               = false
 StringUtils.containsAny("", *)                 = false
 StringUtils.containsAny(*, null)               = false
 StringUtils.containsAny(*, "")                 = false
 StringUtils.containsAny("zzabyycdxx", "za")    = true
 StringUtils.containsAny("zzabyycdxx", "by")    = true
 StringUtils.containsAny("zzabyycdxx", "zy")    = true
 StringUtils.containsAny("zzabyycdxx", "\tx")   = true
 StringUtils.containsAny("zzabyycdxx", "$.#yF") = true
 StringUtils.containsAny("aba", "z")            = false

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4, 3.0 Changed signature from containsAny(String, String) to containsAny(CharSequence, CharSequence)

containsAny

public static boolean containsAny(CharSequence cs,
                                  CharSequence... searchCharSequences)

Checks if the CharSequence contains any of the CharSequences in the given array.

A null cs CharSequence will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)            = false
 StringUtils.containsAny("", *)              = false
 StringUtils.containsAny(*, null)            = false
 StringUtils.containsAny(*, [])              = false
 StringUtils.containsAny("abcd", "ab", null) = true
 StringUtils.containsAny("abcd", "ab", "cd") = true
 StringUtils.containsAny("abc", "d", "abc")  = true

Parameters:: cs - The CharSequence to check, may be null; searchCharSequences - The array of CharSequences to search for, may be null. Individual CharSequences may be null as well.
Returns:: true if any of the search CharSequences are found, false otherwise
Since:: 3.4

containsAnyIgnoreCase

public static boolean containsAnyIgnoreCase(CharSequence cs,
                                            CharSequence... searchCharSequences)

Checks if the CharSequence contains any of the CharSequences in the given array, ignoring case.

A null cs CharSequence will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)            = false
 StringUtils.containsAny("", *)              = false
 StringUtils.containsAny(*, null)            = false
 StringUtils.containsAny(*, [])              = false
 StringUtils.containsAny("abcd", "ab", null) = true
 StringUtils.containsAny("abcd", "ab", "cd") = true
 StringUtils.containsAny("abc", "d", "abc")  = true
 StringUtils.containsAny("abc", "D", "ABC")  = true
 StringUtils.containsAny("ABC", "d", "abc")  = true

Parameters:: cs - The CharSequence to check, may be null; searchCharSequences - The array of CharSequences to search for, may be null. Individual CharSequences may be null as well.
Returns:: true if any of the search CharSequences are found, false otherwise
Since:: 3.12.0

containsIgnoreCase

public static boolean containsIgnoreCase(CharSequence str,
                                         CharSequence searchStr)

Checks if CharSequence contains a search CharSequence irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

A null CharSequence will return false.

 StringUtils.containsIgnoreCase(null, *) = false
 StringUtils.containsIgnoreCase(*, null) = false
 StringUtils.containsIgnoreCase("", "") = true
 StringUtils.containsIgnoreCase("abc", "") = true
 StringUtils.containsIgnoreCase("abc", "a") = true
 StringUtils.containsIgnoreCase("abc", "z") = false
 StringUtils.containsIgnoreCase("abc", "A") = true
 StringUtils.containsIgnoreCase("abc", "Z") = false

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null
Returns:: true if the CharSequence contains the search CharSequence irrespective of case or false if not or null string input
Since:: 3.0 Changed signature from containsIgnoreCase(String, String) to containsIgnoreCase(CharSequence, CharSequence)

containsNone
```
public static boolean containsNone(CharSequence cs,
                                   char... searchChars)
```
Checks that the CharSequence does not contain certain characters.

A null CharSequence will return true. A null invalid character array will return true. An empty CharSequence (length()=0) always returns true.
```
 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", '')      = true
 StringUtils.containsNone("abab", 'xyz') = true
 StringUtils.containsNone("ab1", 'xyz')  = true
 StringUtils.containsNone("abz", 'xyz')  = false
 
```
Parameters:

cs - the CharSequence to check, may be null

searchChars - an array of invalid chars, may be null

Returns:

true if it contains none of the invalid chars, or is null

Since:

2.0, 3.0 Changed signature from containsNone(String, char[]) to containsNone(CharSequence, char...)

containsNone

public static boolean containsNone(CharSequence cs,
                                   String invalidChars)

Checks that the CharSequence does not contain certain characters.

A null CharSequence will return true. A null invalid character array will return true. An empty String ("") always returns true.

 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", "")      = true
 StringUtils.containsNone("abab", "xyz") = true
 StringUtils.containsNone("ab1", "xyz")  = true
 StringUtils.containsNone("abz", "xyz")  = false

Parameters:: cs - the CharSequence to check, may be null; invalidChars - a String of invalid chars, may be null
Returns:: true if it contains none of the invalid chars, or is null
Since:: 2.0, 3.0 Changed signature from containsNone(String, String) to containsNone(CharSequence, String)

containsOnly
```
public static boolean containsOnly(CharSequence cs,
                                   char... valid)
```
Checks if the CharSequence contains only certain characters.

A null CharSequence will return false. A null valid character array will return false. An empty CharSequence (length()=0) always returns true.
```
 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", '')      = false
 StringUtils.containsOnly("abab", 'abc') = true
 StringUtils.containsOnly("ab1", 'abc')  = false
 StringUtils.containsOnly("abz", 'abc')  = false
 
```
Parameters:

cs - the String to check, may be null

valid - an array of valid chars, may be null

Returns:

true if it only contains valid chars and is non-null

Since:

3.0 Changed signature from containsOnly(String, char[]) to containsOnly(CharSequence, char...)

containsOnly

public static boolean containsOnly(CharSequence cs,
                                   String validChars)

Checks if the CharSequence contains only certain characters.

A null CharSequence will return false. A null valid character String will return false. An empty String (length()=0) always returns true.

 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", "")      = false
 StringUtils.containsOnly("abab", "abc") = true
 StringUtils.containsOnly("ab1", "abc")  = false
 StringUtils.containsOnly("abz", "abc")  = false

Parameters:: cs - the CharSequence to check, may be null; validChars - a String of valid chars, may be null
Returns:: true if it only contains valid chars and is non-null
Since:: 2.0, 3.0 Changed signature from containsOnly(String, String) to containsOnly(CharSequence, String)

containsWhitespace
```
public static boolean containsWhitespace(CharSequence seq)
```
Check whether the given CharSequence contains any whitespace characters.

Whitespace is defined by Character.isWhitespace(char).

Parameters:

seq - the CharSequence to check (may be null)

Returns:

true if the CharSequence is not empty and contains at least 1 (breaking) whitespace character

Since:

3.0

countMatches

public static int countMatches(CharSequence str,
                               char ch)

Counts how many times the char appears in the given string.

A null or empty ("") String input returns 0.

 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", 0)  = 0
 StringUtils.countMatches("abba", 'a')   = 2
 StringUtils.countMatches("abba", 'b')  = 2
 StringUtils.countMatches("abba", 'x') = 0

Parameters:: str - the CharSequence to check, may be null; ch - the char to count
Returns:: the number of occurrences, 0 if the CharSequence is null
Since:: 3.4

countMatches

public static int countMatches(CharSequence str,
                               CharSequence sub)

Counts how many times the substring appears in the larger string. Note that the code only counts non-overlapping matches.

A null or empty ("") String input returns 0.

 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", null)  = 0
 StringUtils.countMatches("abba", "")    = 0
 StringUtils.countMatches("abba", "a")   = 2
 StringUtils.countMatches("abba", "ab")  = 1
 StringUtils.countMatches("abba", "xxx") = 0
 StringUtils.countMatches("ababa", "aba") = 1

Parameters:: str - the CharSequence to check, may be null; sub - the substring to count, may be null
Returns:: the number of occurrences, 0 if either CharSequence is null
Since:: 3.0 Changed signature from countMatches(String, String) to countMatches(CharSequence, CharSequence)

defaultIfBlank
```
public static <T extends CharSequence> T defaultIfBlank(T str,
                                                        T defaultStr)
```
Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.

Whitespace is defined by Character.isWhitespace(char).
```
 StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
 StringUtils.defaultIfBlank("", "NULL")    = "NULL"
 StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
 StringUtils.defaultIfBlank("bat", "NULL") = "bat"
 StringUtils.defaultIfBlank("", null)      = null
 
```
Type Parameters:

T - the specific kind of CharSequence

Parameters:

str - the CharSequence to check, may be null

defaultStr - the default CharSequence to return if the input is whitespace, empty ("") or null, may be null

Returns:

the passed in CharSequence, or the default

See Also:

defaultString(String, String)

defaultIfEmpty
```
public static <T extends CharSequence> T defaultIfEmpty(T str,
                                                        T defaultStr)
```
Returns either the passed in CharSequence, or if the CharSequence is empty or null, the value of defaultStr.
```
 StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
 StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
 StringUtils.defaultIfEmpty(" ", "NULL")   = " "
 StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
 StringUtils.defaultIfEmpty("", null)      = null
 
```
Type Parameters:

T - the specific kind of CharSequence

Parameters:

str - the CharSequence to check, may be null

defaultStr - the default CharSequence to return if the input is empty ("") or null, may be null

Returns:

the passed in CharSequence, or the default

See Also:

defaultString(String, String)

defaultString
```
public static String defaultString(String str)
```
Returns either the passed in String, or if the String is null, an empty String ("").
```
 StringUtils.defaultString(null)  = ""
 StringUtils.defaultString("")    = ""
 StringUtils.defaultString("bat") = "bat"
 
```
Parameters:

str - the String to check, may be null

Returns:

the passed in String, or the empty String if it was null

See Also:

ObjectUtils.toString(Object), String.valueOf(Object)

defaultString
```
public static String defaultString(String str,
                                   String defaultStr)
```
Returns either the passed in String, or if the String is null, the value of defaultStr.
```
 StringUtils.defaultString(null, "NULL")  = "NULL"
 StringUtils.defaultString("", "NULL")    = ""
 StringUtils.defaultString("bat", "NULL") = "bat"
 
```
Parameters:

str - the String to check, may be null

defaultStr - the default String to return if the input is null, may be null

Returns:

the passed in String, or the default if it was null

See Also:

ObjectUtils.toString(Object,String), String.valueOf(Object)

deleteWhitespace

public static String deleteWhitespace(String str)

Deletes all whitespaces from a String as defined by Character.isWhitespace(char).

 StringUtils.deleteWhitespace(null)         = null
 StringUtils.deleteWhitespace("")           = ""
 StringUtils.deleteWhitespace("abc")        = "abc"
 StringUtils.deleteWhitespace("   ab  c  ") = "abc"

Parameters:: str - the String to delete whitespace from, may be null
Returns:: the String without whitespaces, null if null String input

difference
```
public static String difference(String str1,
                                String str2)
```
Compares two Strings, and returns the portion where they differ. More precisely, return the remainder of the second String, starting from where it's different from the first. This means that the difference between "abc" and "ab" is the empty String and not "c".

For example, difference("i am a machine", "i am a robot") -> "robot".
```
 StringUtils.difference(null, null) = null
 StringUtils.difference("", "") = ""
 StringUtils.difference("", "abc") = "abc"
 StringUtils.difference("abc", "") = ""
 StringUtils.difference("abc", "abc") = ""
 StringUtils.difference("abc", "ab") = ""
 StringUtils.difference("ab", "abxyz") = "xyz"
 StringUtils.difference("abcde", "abxyz") = "xyz"
 StringUtils.difference("abcde", "xyz") = "xyz"
 
```
Parameters:

str1 - the first String, may be null

str2 - the second String, may be null

Returns:

the portion of str2 where it differs from str1; returns the empty String if they are equal

Since:

2.0

See Also:

indexOfDifference(CharSequence,CharSequence)

endsWith
```
public static boolean endsWith(CharSequence str,
                               CharSequence suffix)
```
Check if a CharSequence ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.endsWith(null, null)      = true
 StringUtils.endsWith(null, "def")     = false
 StringUtils.endsWith("abcdef", null)  = false
 StringUtils.endsWith("abcdef", "def") = true
 StringUtils.endsWith("ABCDEF", "def") = false
 StringUtils.endsWith("ABCDEF", "cde") = false
 StringUtils.endsWith("ABCDEF", "")    = true
 
```
Parameters:

str - the CharSequence to check, may be null

suffix - the suffix to find, may be null

Returns:

true if the CharSequence ends with the suffix, case sensitive, or both null

Since:

2.4, 3.0 Changed signature from endsWith(String, String) to endsWith(CharSequence, CharSequence)

See Also:

String.endsWith(String)

endsWithAny

public static boolean endsWithAny(CharSequence sequence,
                                  CharSequence... searchStrings)

Check if a CharSequence ends with any of the provided case-sensitive suffixes.

 StringUtils.endsWithAny(null, null)      = false
 StringUtils.endsWithAny(null, new String[] {"abc"})  = false
 StringUtils.endsWithAny("abcxyz", null)     = false
 StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
 StringUtils.endsWithAny("abcXYZ", "def", "XYZ") = true
 StringUtils.endsWithAny("abcXYZ", "def", "xyz") = false

Parameters:: sequence - the CharSequence to check, may be null; searchStrings - the case-sensitive CharSequences to find, may be empty or contain null
Returns:: true if the input sequence is null AND no searchStrings are provided, or the input sequence ends in any of the provided case-sensitive searchStrings.
Since:: 3.0
See Also:: endsWith(CharSequence, CharSequence)

endsWithIgnoreCase
```
public static boolean endsWithIgnoreCase(CharSequence str,
                                         CharSequence suffix)
```
Case insensitive check if a CharSequence ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.
```
 StringUtils.endsWithIgnoreCase(null, null)      = true
 StringUtils.endsWithIgnoreCase(null, "def")     = false
 StringUtils.endsWithIgnoreCase("abcdef", null)  = false
 StringUtils.endsWithIgnoreCase("abcdef", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false
 
```
Parameters:

str - the CharSequence to check, may be null

suffix - the suffix to find, may be null

Returns:

true if the CharSequence ends with the suffix, case insensitive, or both null

Since:

2.4, 3.0 Changed signature from endsWithIgnoreCase(String, String) to endsWithIgnoreCase(CharSequence, CharSequence)

See Also:

String.endsWith(String)

equals
```
public static boolean equals(CharSequence cs1,
                             CharSequence cs2)
```
Compares two CharSequences, returning true if they represent equal sequences of characters.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.equals(null, null)   = true
 StringUtils.equals(null, "abc")  = false
 StringUtils.equals("abc", null)  = false
 StringUtils.equals("abc", "abc") = true
 StringUtils.equals("abc", "ABC") = false
 
```
Parameters:

cs1 - the first CharSequence, may be null

cs2 - the second CharSequence, may be null

Returns:

true if the CharSequences are equal (case-sensitive), or both null

Since:

3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)

See Also:

Object.equals(Object), equalsIgnoreCase(CharSequence, CharSequence)

equalsAny

public static boolean equalsAny(CharSequence string,
                                CharSequence... searchStrings)

Compares given string to a CharSequences vararg of searchStrings, returning true if the string is equal to any of the searchStrings.

 StringUtils.equalsAny(null, (CharSequence[]) null) = false
 StringUtils.equalsAny(null, null, null)    = true
 StringUtils.equalsAny(null, "abc", "def")  = false
 StringUtils.equalsAny("abc", null, "def")  = false
 StringUtils.equalsAny("abc", "abc", "def") = true
 StringUtils.equalsAny("abc", "ABC", "DEF") = false

Parameters:: string - to compare, may be null.; searchStrings - a vararg of strings, may be null.
Returns:: true if the string is equal (case-sensitive) to any other element of searchStrings; false if searchStrings is null or contains no matches.
Since:: 3.5

equalsAnyIgnoreCase

public static boolean equalsAnyIgnoreCase(CharSequence string,
                                          CharSequence... searchStrings)

Compares given string to a CharSequences vararg of searchStrings, returning true if the string is equal to any of the searchStrings, ignoring case.

 StringUtils.equalsAnyIgnoreCase(null, (CharSequence[]) null) = false
 StringUtils.equalsAnyIgnoreCase(null, null, null)    = true
 StringUtils.equalsAnyIgnoreCase(null, "abc", "def")  = false
 StringUtils.equalsAnyIgnoreCase("abc", null, "def")  = false
 StringUtils.equalsAnyIgnoreCase("abc", "abc", "def") = true
 StringUtils.equalsAnyIgnoreCase("abc", "ABC", "DEF") = true

Parameters:: string - to compare, may be null.; searchStrings - a vararg of strings, may be null.
Returns:: true if the string is equal (case-insensitive) to any other element of searchStrings; false if searchStrings is null or contains no matches.
Since:: 3.5

equalsIgnoreCase
```
public static boolean equalsIgnoreCase(CharSequence cs1,
                                       CharSequence cs2)
```
Compares two CharSequences, returning true if they represent equal sequences of characters, ignoring case.

nulls are handled without exceptions. Two null references are considered equal. The comparison is case insensitive.
```
 StringUtils.equalsIgnoreCase(null, null)   = true
 StringUtils.equalsIgnoreCase(null, "abc")  = false
 StringUtils.equalsIgnoreCase("abc", null)  = false
 StringUtils.equalsIgnoreCase("abc", "abc") = true
 StringUtils.equalsIgnoreCase("abc", "ABC") = true
 
```
Parameters:

cs1 - the first CharSequence, may be null

cs2 - the second CharSequence, may be null

Returns:

true if the CharSequences are equal (case-insensitive), or both null

Since:

3.0 Changed signature from equalsIgnoreCase(String, String) to equalsIgnoreCase(CharSequence, CharSequence)

See Also:

equals(CharSequence, CharSequence)

firstNonBlank

@SafeVarargs
public static <T extends CharSequence> T firstNonBlank(T... values)

Returns the first value in the array which is not empty (""), null or whitespace only.

Whitespace is defined by Character.isWhitespace(char).

If all values are blank or the array is null or empty then null is returned.

 StringUtils.firstNonBlank(null, null, null)     = null
 StringUtils.firstNonBlank(null, "", " ")        = null
 StringUtils.firstNonBlank("abc")                = "abc"
 StringUtils.firstNonBlank(null, "xyz")          = "xyz"
 StringUtils.firstNonBlank(null, "", " ", "xyz") = "xyz"
 StringUtils.firstNonBlank(null, "xyz", "abc")   = "xyz"
 StringUtils.firstNonBlank()                     = null

Type Parameters:: T - the specific kind of CharSequence
Parameters:: values - the values to test, may be null or empty
Returns:: the first value from values which is not blank, or null if there are no non-blank values
Since:: 3.8

firstNonEmpty

@SafeVarargs
public static <T extends CharSequence> T firstNonEmpty(T... values)

Returns the first value in the array which is not empty.

If all values are empty or the array is null or empty then null is returned.

 StringUtils.firstNonEmpty(null, null, null)   = null
 StringUtils.firstNonEmpty(null, null, "")     = null
 StringUtils.firstNonEmpty(null, "", " ")      = " "
 StringUtils.firstNonEmpty("abc")              = "abc"
 StringUtils.firstNonEmpty(null, "xyz")        = "xyz"
 StringUtils.firstNonEmpty("", "xyz")          = "xyz"
 StringUtils.firstNonEmpty(null, "xyz", "abc") = "xyz"
 StringUtils.firstNonEmpty()                   = null

Type Parameters:: T - the specific kind of CharSequence
Parameters:: values - the values to test, may be null or empty
Returns:: the first value from values which is not empty, or null if there are no non-empty values
Since:: 3.8

getBytes
```
public static byte[] getBytes(String string,
                              Charset charset)
```
Calls String.getBytes(Charset) in a null-safe manner.

Parameters:

string - input string

charset - The Charset to encode the String. If null, then use the default Charset.

Returns:

The empty byte[] if string is null, the result of String.getBytes(Charset) otherwise.

Since:

3.10

See Also:

String.getBytes(Charset)

getBytes
```
public static byte[] getBytes(String string,
                              String charset)
                       throws UnsupportedEncodingException
```
Calls String.getBytes(String) in a null-safe manner.

Parameters:

string - input string

charset - The Charset name to encode the String. If null, then use the default Charset.

Returns:

The empty byte[] if string is null, the result of String.getBytes(String) otherwise.

Throws:

UnsupportedEncodingException - Thrown when the named charset is not supported.

Since:

3.10

See Also:

String.getBytes(String)

getCommonPrefix

public static String getCommonPrefix(String... strs)

Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

For example, getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "

 StringUtils.getCommonPrefix(null) = ""
 StringUtils.getCommonPrefix(new String[] {}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"", null}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
 StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
 StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
 StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "

Parameters:: strs - array of String objects, entries may be null
Returns:: the initial sequence of characters that are common to all Strings in the array; empty String if the array is null, the elements are all null or if there is no common prefix.
Since:: 2.4

getDigits
```
public static String getDigits(String str)
```
Checks if a String str contains Unicode digits, if yes then concatenate all the digits in str and return it as a String.

An empty ("") String will be returned if no digits found in str.
```
 StringUtils.getDigits(null)  = null
 StringUtils.getDigits("")    = ""
 StringUtils.getDigits("abc") = ""
 StringUtils.getDigits("1000$") = "1000"
 StringUtils.getDigits("1123~45") = "112345"
 StringUtils.getDigits("(541) 754-3010") = "5417543010"
 StringUtils.getDigits("१२३") = "१२३"
 
```
Parameters:

str - the String to extract digits from, may be null

Returns:

String with only digits, or an empty ("") String if no digits found, or null String if str is null

Since:

3.6

getFuzzyDistance

@Deprecated
public static int getFuzzyDistance(CharSequence term,
                                               CharSequence query,
                                               Locale locale)

Deprecated. as of 3.6, use commons-text FuzzyScore instead

Find the Fuzzy Distance which indicates the similarity score between two Strings.

This string matching algorithm is similar to the algorithms of editors such as Sublime Text, TextMate, Atom and others. One point is given for every matched character. Subsequent matches yield two bonus points. A higher score indicates a higher similarity.

 StringUtils.getFuzzyDistance(null, null, null)                                    = IllegalArgumentException
 StringUtils.getFuzzyDistance("", "", Locale.ENGLISH)                              = 0
 StringUtils.getFuzzyDistance("Workshop", "b", Locale.ENGLISH)                     = 0
 StringUtils.getFuzzyDistance("Room", "o", Locale.ENGLISH)                         = 1
 StringUtils.getFuzzyDistance("Workshop", "w", Locale.ENGLISH)                     = 1
 StringUtils.getFuzzyDistance("Workshop", "ws", Locale.ENGLISH)                    = 2
 StringUtils.getFuzzyDistance("Workshop", "wo", Locale.ENGLISH)                    = 4
 StringUtils.getFuzzyDistance("Apache Software Foundation", "asf", Locale.ENGLISH) = 3

Parameters:: term - a full term that should be matched against, must not be null; query - the query that will be matched against a term, must not be null; locale - This string matching logic is case insensitive. A locale is necessary to normalize both Strings to lower case.
Returns:: result score
Throws:: IllegalArgumentException - if either String input null or Locale input null
Since:: 3.4

getIfBlank
```
public static <T extends CharSequence> T getIfBlank(T str,
                                                    Supplier<T> defaultSupplier)
```
Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value supplied by defaultStrSupplier.

Whitespace is defined by Character.isWhitespace(char).

Caller responsible for thread-safety and exception handling of default value supplier
```
 
 StringUtils.getIfBlank(null, () -> "NULL")   = "NULL"
 StringUtils.getIfBlank("", () -> "NULL")     = "NULL"
 StringUtils.getIfBlank(" ", () -> "NULL")    = "NULL"
 StringUtils.getIfBlank("bat", () -> "NULL")  = "bat"
 StringUtils.getIfBlank("", () -> null)       = null
 StringUtils.getIfBlank("", null)             = null
 
```
Type Parameters:

T - the specific kind of CharSequence

Parameters:

str - the CharSequence to check, may be null

defaultSupplier - the supplier of default CharSequence to return if the input is whitespace, empty ("") or null, may be null

Returns:

the passed in CharSequence, or the default

Since:

3.10

See Also:

defaultString(String, String)

getIfEmpty

public static <T extends CharSequence> T getIfEmpty(T str,
                                                    Supplier<T> defaultSupplier)

Returns either the passed in CharSequence, or if the CharSequence is empty or null, the value supplied by defaultStrSupplier.

Caller responsible for thread-safety and exception handling of default value supplier

 
 StringUtils.getIfEmpty(null, () -> "NULL")    = "NULL"
 StringUtils.getIfEmpty("", () -> "NULL")      = "NULL"
 StringUtils.getIfEmpty(" ", () -> "NULL")     = " "
 StringUtils.getIfEmpty("bat", () -> "NULL")   = "bat"
 StringUtils.getIfEmpty("", () -> null)        = null
 StringUtils.getIfEmpty("", null)              = null

Type Parameters:: T - the specific kind of CharSequence
Parameters:: str - the CharSequence to check, may be null; defaultSupplier - the supplier of default CharSequence to return if the input is empty ("") or null, may be null
Returns:: the passed in CharSequence, or the default
Since:: 3.10
See Also:: defaultString(String, String)

getJaroWinklerDistance

@Deprecated
public static double getJaroWinklerDistance(CharSequence first,
                                                        CharSequence second)

Deprecated. as of 3.6, use commons-text JaroWinklerDistance instead

Find the Jaro Winkler Distance which indicates the similarity score between two Strings.

The Jaro measure is the weighted sum of percentage of matched characters from each file and transposed characters. Winkler increased this measure for matching initial characters.

This implementation is based on the Jaro Winkler similarity algorithm from http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance.

 StringUtils.getJaroWinklerDistance(null, null)          = IllegalArgumentException
 StringUtils.getJaroWinklerDistance("", "")              = 0.0
 StringUtils.getJaroWinklerDistance("", "a")             = 0.0
 StringUtils.getJaroWinklerDistance("aaapppp", "")       = 0.0
 StringUtils.getJaroWinklerDistance("frog", "fog")       = 0.93
 StringUtils.getJaroWinklerDistance("fly", "ant")        = 0.0
 StringUtils.getJaroWinklerDistance("elephant", "hippo") = 0.44
 StringUtils.getJaroWinklerDistance("hippo", "elephant") = 0.44
 StringUtils.getJaroWinklerDistance("hippo", "zzzzzzzz") = 0.0
 StringUtils.getJaroWinklerDistance("hello", "hallo")    = 0.88
 StringUtils.getJaroWinklerDistance("ABC Corporation", "ABC Corp") = 0.93
 StringUtils.getJaroWinklerDistance("D N H Enterprises Inc", "D & H Enterprises, Inc.") = 0.95
 StringUtils.getJaroWinklerDistance("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.92
 StringUtils.getJaroWinklerDistance("PENNSYLVANIA", "PENNCISYLVNIA") = 0.88

Parameters:: first - the first String, must not be null; second - the second String, must not be null
Returns:: result distance
Throws:: IllegalArgumentException - if either String input null
Since:: 3.3

getLevenshteinDistance

@Deprecated
public static int getLevenshteinDistance(CharSequence s,
                                                     CharSequence t)

Deprecated. as of 3.6, use commons-text LevenshteinDistance instead

Find the Levenshtein distance between two Strings.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

The implementation uses a single-dimensional array of length s.length() + 1. See http://blog.softwx.net/2014/12/optimizing-levenshtein-algorithm-in-c.html for details.

 StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance("", "")              = 0
 StringUtils.getLevenshteinDistance("", "a")             = 1
 StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
 StringUtils.getLevenshteinDistance("frog", "fog")       = 1
 StringUtils.getLevenshteinDistance("fly", "ant")        = 3
 StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
 StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
 StringUtils.getLevenshteinDistance("hello", "hallo")    = 1

Parameters:: s - the first String, must not be null; t - the second String, must not be null
Returns:: result distance
Throws:: IllegalArgumentException - if either String input null
Since:: 3.0 Changed signature from getLevenshteinDistance(String, String) to getLevenshteinDistance(CharSequence, CharSequence)

getLevenshteinDistance

@Deprecated
public static int getLevenshteinDistance(CharSequence s,
                                                     CharSequence t,
                                                     int threshold)

Deprecated. as of 3.6, use commons-text LevenshteinDistance instead

Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield and Chas Emerick's implementation of the Levenshtein distance algorithm from http://www.merriampark.com/ld.htm

 StringUtils.getLevenshteinDistance(null, *, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, *, -1)               = IllegalArgumentException
 StringUtils.getLevenshteinDistance("", "", 0)              = 0
 StringUtils.getLevenshteinDistance("aaapppp", "", 8)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 7)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 6))      = -1
 StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7
 StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1
 StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1

Parameters:: s - the first String, must not be null; t - the second String, must not be null; threshold - the target threshold, must not be negative
Returns:: result distance, or -1 if the distance would be greater than the threshold
Throws:: IllegalArgumentException - if either String input null or negative threshold

indexOf

public static int indexOf(CharSequence seq,
                          CharSequence searchSeq)

Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.

A null CharSequence will return -1.

 StringUtils.indexOf(null, *)          = -1
 StringUtils.indexOf(*, null)          = -1
 StringUtils.indexOf("", "")           = 0
 StringUtils.indexOf("", *)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a")  = 0
 StringUtils.indexOf("aabaabaa", "b")  = 2
 StringUtils.indexOf("aabaabaa", "ab") = 1
 StringUtils.indexOf("aabaabaa", "")   = 0

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, String) to indexOf(CharSequence, CharSequence)

indexOf

public static int indexOf(CharSequence seq,
                          CharSequence searchSeq,
                          int startPos)

Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.

A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.

 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf(*, null, *)          = -1
 StringUtils.indexOf("", "", 0)           = 0
 StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a", 0)  = 0
 StringUtils.indexOf("aabaabaa", "b", 0)  = 2
 StringUtils.indexOf("aabaabaa", "ab", 0) = 1
 StringUtils.indexOf("aabaabaa", "b", 3)  = 5
 StringUtils.indexOf("aabaabaa", "b", 9)  = -1
 StringUtils.indexOf("aabaabaa", "b", -1) = 2
 StringUtils.indexOf("aabaabaa", "", 2)   = 2
 StringUtils.indexOf("abc", "", 9)        = 3

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search CharSequence (always ≥ startPos), -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, String, int) to indexOf(CharSequence, CharSequence, int)

indexOf
```
public static int indexOf(CharSequence seq,
                          int searchChar)
```
Returns the index within seq of the first occurrence of the specified character. If a character with value searchChar occurs in the character sequence represented by seq CharSequence object, then the index (in Unicode code units) of the first such occurrence is returned. For values of searchChar in the range from 0 to 0xFFFF (inclusive), this is the smallest value k such that:
```
 this.charAt(k) == searchChar
 
```
is true. For other values of searchChar, it is the smallest value k such that:
```
 this.codePointAt(k) == searchChar
 
```
is true. In either case, if no such character occurs in seq, then INDEX_NOT_FOUND (-1) is returned.
Furthermore, a null or empty ("") CharSequence will return INDEX_NOT_FOUND (-1).
```
 StringUtils.indexOf(null, *)         = -1
 StringUtils.indexOf("", *)           = -1
 StringUtils.indexOf("aabaabaa", 'a') = 0
 StringUtils.indexOf("aabaabaa", 'b') = 2
 
```
Parameters:

seq - the CharSequence to check, may be null

searchChar - the character to find

Returns:

the first index of the search character, -1 if no match or null string input

Since:

2.0, 3.0 Changed signature from indexOf(String, int) to indexOf(CharSequence, int), 3.6 Updated CharSequenceUtils call to behave more like String

indexOf
```
public static int indexOf(CharSequence seq,
                          int searchChar,
                          int startPos)
```
Returns the index within seq of the first occurrence of the specified character, starting the search at the specified index.
If a character with value searchChar occurs in the character sequence represented by the seq CharSequence object at an index no smaller than startPos, then the index of the first such occurrence is returned. For values of searchChar in the range from 0 to 0xFFFF (inclusive), this is the smallest value k such that:
```
 (this.charAt(k) == searchChar) && (k >= startPos)
 
```
is true. For other values of searchChar, it is the smallest value k such that:
```
 (this.codePointAt(k) == searchChar) && (k >= startPos)
 
```
is true. In either case, if no such character occurs in seq at or after position startPos, then -1 is returned.
There is no restriction on the value of startPos. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string: (INDEX_NOT_FOUND) -1 is returned. Furthermore, a null or empty ("") CharSequence will return (INDEX_NOT_FOUND) -1.
All indices are specified in char values (Unicode code units).
```
 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf("", *, *)            = -1
 StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
 StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
 StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
 StringUtils.indexOf("aabaabaa", 'b', -1) = 2
 
```
Parameters:

seq - the CharSequence to check, may be null

searchChar - the character to find

startPos - the start position, negative treated as zero

Returns:

the first index of the search character (always ≥ startPos), -1 if no match or null string input

Since:

2.0, 3.0 Changed signature from indexOf(String, int, int) to indexOf(CharSequence, int, int), 3.6 Updated CharSequenceUtils call to behave more like String

indexOfAny

public static int indexOfAny(CharSequence cs,
                             char... searchChars)

Search a CharSequence to find the first index of any character in the given set of characters.

A null String will return -1. A null or zero length search array will return -1.

 StringUtils.indexOfAny(null, *)                  = -1
 StringUtils.indexOfAny("", *)                    = -1
 StringUtils.indexOfAny(*, null)                  = -1
 StringUtils.indexOfAny(*, [])                    = -1
 StringUtils.indexOfAny("zzabyycdxx", ['z', 'a']) = 0
 StringUtils.indexOfAny("zzabyycdxx", ['b', 'y']) = 3
 StringUtils.indexOfAny("aba", ['z'])             = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAny(String, char[]) to indexOfAny(CharSequence, char...)

indexOfAny

public static int indexOfAny(CharSequence str,
                             CharSequence... searchStrs)

Find the first index of any of a set of potential substrings.

A null CharSequence will return -1. A null or zero length search array will return -1. A null search array entry will be ignored, but a search array containing "" will return 0 if str is not null. This method uses String.indexOf(String) if possible.

 StringUtils.indexOfAny(null, *)                      = -1
 StringUtils.indexOfAny(*, null)                      = -1
 StringUtils.indexOfAny(*, [])                        = -1
 StringUtils.indexOfAny("zzabyycdxx", ["ab", "cd"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["cd", "ab"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["mn", "op"])   = -1
 StringUtils.indexOfAny("zzabyycdxx", ["zab", "aby"]) = 1
 StringUtils.indexOfAny("zzabyycdxx", [""])           = 0
 StringUtils.indexOfAny("", [""])                     = 0
 StringUtils.indexOfAny("", ["a"])                    = -1

Parameters:: str - the CharSequence to check, may be null; searchStrs - the CharSequences to search for, may be null
Returns:: the first index of any of the searchStrs in str, -1 if no match
Since:: 3.0 Changed signature from indexOfAny(String, String[]) to indexOfAny(CharSequence, CharSequence...)

indexOfAny

public static int indexOfAny(CharSequence cs,
                             String searchChars)

Search a CharSequence to find the first index of any character in the given set of characters.

A null String will return -1. A null search string will return -1.

 StringUtils.indexOfAny(null, *)            = -1
 StringUtils.indexOfAny("", *)              = -1
 StringUtils.indexOfAny(*, null)            = -1
 StringUtils.indexOfAny(*, "")              = -1
 StringUtils.indexOfAny("zzabyycdxx", "za") = 0
 StringUtils.indexOfAny("zzabyycdxx", "by") = 3
 StringUtils.indexOfAny("aba", "z")         = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAny(String, String) to indexOfAny(CharSequence, String)

indexOfAnyBut

public static int indexOfAnyBut(CharSequence cs,
                                char... searchChars)

Searches a CharSequence to find the first index of any character not in the given set of characters.

A null CharSequence will return -1. A null or zero length search array will return -1.

 StringUtils.indexOfAnyBut(null, *)                              = -1
 StringUtils.indexOfAnyBut("", *)                                = -1
 StringUtils.indexOfAnyBut(*, null)                              = -1
 StringUtils.indexOfAnyBut(*, [])                                = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
 StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
 StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAnyBut(String, char[]) to indexOfAnyBut(CharSequence, char...)

indexOfAnyBut

public static int indexOfAnyBut(CharSequence seq,
                                CharSequence searchChars)

Search a CharSequence to find the first index of any character not in the given set of characters.

A null CharSequence will return -1. A null or empty search string will return -1.

 StringUtils.indexOfAnyBut(null, *)            = -1
 StringUtils.indexOfAnyBut("", *)              = -1
 StringUtils.indexOfAnyBut(*, null)            = -1
 StringUtils.indexOfAnyBut(*, "")              = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
 StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
 StringUtils.indexOfAnyBut("aba", "ab")        = -1

Parameters:: seq - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAnyBut(String, String) to indexOfAnyBut(CharSequence, CharSequence)

indexOfDifference

public static int indexOfDifference(CharSequence... css)

Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.

For example, indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7

 StringUtils.indexOfDifference(null) = -1
 StringUtils.indexOfDifference(new String[] {}) = -1
 StringUtils.indexOfDifference(new String[] {"abc"}) = -1
 StringUtils.indexOfDifference(new String[] {null, null}) = -1
 StringUtils.indexOfDifference(new String[] {"", ""}) = -1
 StringUtils.indexOfDifference(new String[] {"", null}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
 StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
 StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
 StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
 StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
 StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7

Parameters:: css - array of CharSequences, entries may be null
Returns:: the index where the strings begin to differ; -1 if they are all equal
Since:: 2.4, 3.0 Changed signature from indexOfDifference(String...) to indexOfDifference(CharSequence...)

indexOfDifference

public static int indexOfDifference(CharSequence cs1,
                                    CharSequence cs2)

Compares two CharSequences, and returns the index at which the CharSequences begin to differ.

For example, indexOfDifference("i am a machine", "i am a robot") -> 7

 StringUtils.indexOfDifference(null, null) = -1
 StringUtils.indexOfDifference("", "") = -1
 StringUtils.indexOfDifference("", "abc") = 0
 StringUtils.indexOfDifference("abc", "") = 0
 StringUtils.indexOfDifference("abc", "abc") = -1
 StringUtils.indexOfDifference("ab", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "xyz") = 0

Parameters:: cs1 - the first CharSequence, may be null; cs2 - the second CharSequence, may be null
Returns:: the index where cs1 and cs2 begin to differ; -1 if they are equal
Since:: 2.0, 3.0 Changed signature from indexOfDifference(String, String) to indexOfDifference(CharSequence, CharSequence)

indexOfIgnoreCase
```
public static int indexOfIgnoreCase(CharSequence str,
                                    CharSequence searchStr)
```
Case in-sensitive find of the first index within a CharSequence.

A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.
```
 StringUtils.indexOfIgnoreCase(null, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null)          = -1
 StringUtils.indexOfIgnoreCase("", "")           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1
 
```
Parameters:

str - the CharSequence to check, may be null

searchStr - the CharSequence to find, may be null

Returns:

the first index of the search CharSequence, -1 if no match or null string input

Since:

2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String) to indexOfIgnoreCase(CharSequence, CharSequence)

indexOfIgnoreCase

public static int indexOfIgnoreCase(CharSequence str,
                                    CharSequence searchStr,
                                    int startPos)

Case in-sensitive find of the first index within a CharSequence from the specified position.

 StringUtils.indexOfIgnoreCase(null, *, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null, *)          = -1
 StringUtils.indexOfIgnoreCase("", "", 0)           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
 StringUtils.indexOfIgnoreCase("abc", "", 9)        = -1

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search CharSequence (always ≥ startPos), -1 if no match or null string input
Since:: 2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String, int) to indexOfIgnoreCase(CharSequence, CharSequence, int)

isAllBlank

public static boolean isAllBlank(CharSequence... css)

Checks if all of the CharSequences are empty (""), null or whitespace only.

Whitespace is defined by Character.isWhitespace(char).

 StringUtils.isAllBlank(null)             = true
 StringUtils.isAllBlank(null, "foo")      = false
 StringUtils.isAllBlank(null, null)       = true
 StringUtils.isAllBlank("", "bar")        = false
 StringUtils.isAllBlank("bob", "")        = false
 StringUtils.isAllBlank("  bob  ", null)  = false
 StringUtils.isAllBlank(" ", "bar")       = false
 StringUtils.isAllBlank("foo", "bar")     = false
 StringUtils.isAllBlank(new String[] {})  = true

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if all of the CharSequences are empty or null or whitespace only
Since:: 3.6

isAllEmpty

public static boolean isAllEmpty(CharSequence... css)

Checks if all of the CharSequences are empty ("") or null.

 StringUtils.isAllEmpty(null)             = true
 StringUtils.isAllEmpty(null, "")         = true
 StringUtils.isAllEmpty(new String[] {})  = true
 StringUtils.isAllEmpty(null, "foo")      = false
 StringUtils.isAllEmpty("", "bar")        = false
 StringUtils.isAllEmpty("bob", "")        = false
 StringUtils.isAllEmpty("  bob  ", null)  = false
 StringUtils.isAllEmpty(" ", "bar")       = false
 StringUtils.isAllEmpty("foo", "bar")     = false

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if all of the CharSequences are empty or null
Since:: 3.6

isAllLowerCase

public static boolean isAllLowerCase(CharSequence cs)

Checks if the CharSequence contains only lowercase characters.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isAllLowerCase(null)   = false
 StringUtils.isAllLowerCase("")     = false
 StringUtils.isAllLowerCase("  ")   = false
 StringUtils.isAllLowerCase("abc")  = true
 StringUtils.isAllLowerCase("abC")  = false
 StringUtils.isAllLowerCase("ab c") = false
 StringUtils.isAllLowerCase("ab1c") = false
 StringUtils.isAllLowerCase("ab/c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains lowercase characters, and is non-null
Since:: 2.5, 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)

isAllUpperCase

public static boolean isAllUpperCase(CharSequence cs)

Checks if the CharSequence contains only uppercase characters.

null will return false. An empty String (length()=0) will return false.

 StringUtils.isAllUpperCase(null)   = false
 StringUtils.isAllUpperCase("")     = false
 StringUtils.isAllUpperCase("  ")   = false
 StringUtils.isAllUpperCase("ABC")  = true
 StringUtils.isAllUpperCase("aBC")  = false
 StringUtils.isAllUpperCase("A C")  = false
 StringUtils.isAllUpperCase("A1C")  = false
 StringUtils.isAllUpperCase("A/C")  = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains uppercase characters, and is non-null
Since:: 2.5, 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)

isAlpha
```
public static boolean isAlpha(CharSequence cs)
```
Checks if the CharSequence contains only Unicode letters.

null will return false. An empty CharSequence (length()=0) will return false.
```
 StringUtils.isAlpha(null)   = false
 StringUtils.isAlpha("")     = false
 StringUtils.isAlpha("  ")   = false
 StringUtils.isAlpha("abc")  = true
 StringUtils.isAlpha("ab2c") = false
 StringUtils.isAlpha("ab-c") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains letters, and is non-null

Since:

3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence), 3.0 Changed "" to return false and not true

isAlphanumeric
```
public static boolean isAlphanumeric(CharSequence cs)
```
Checks if the CharSequence contains only Unicode letters or digits.

null will return false. An empty CharSequence (length()=0) will return false.
```
 StringUtils.isAlphanumeric(null)   = false
 StringUtils.isAlphanumeric("")     = false
 StringUtils.isAlphanumeric("  ")   = false
 StringUtils.isAlphanumeric("abc")  = true
 StringUtils.isAlphanumeric("ab c") = false
 StringUtils.isAlphanumeric("ab2c") = true
 StringUtils.isAlphanumeric("ab-c") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains letters or digits, and is non-null

Since:

3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence), 3.0 Changed "" to return false and not true

isAlphanumericSpace

public static boolean isAlphanumericSpace(CharSequence cs)

Checks if the CharSequence contains only Unicode letters, digits or space (' ').

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isAlphanumericSpace(null)   = false
 StringUtils.isAlphanumericSpace("")     = true
 StringUtils.isAlphanumericSpace("  ")   = true
 StringUtils.isAlphanumericSpace("abc")  = true
 StringUtils.isAlphanumericSpace("ab c") = true
 StringUtils.isAlphanumericSpace("ab2c") = true
 StringUtils.isAlphanumericSpace("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains letters, digits or space, and is non-null
Since:: 3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence)

isAlphaSpace
```
public static boolean isAlphaSpace(CharSequence cs)
```
Checks if the CharSequence contains only Unicode letters and space (' ').

null will return false An empty CharSequence (length()=0) will return true.
```
 StringUtils.isAlphaSpace(null)   = false
 StringUtils.isAlphaSpace("")     = true
 StringUtils.isAlphaSpace("  ")   = true
 StringUtils.isAlphaSpace("abc")  = true
 StringUtils.isAlphaSpace("ab c") = true
 StringUtils.isAlphaSpace("ab2c") = false
 StringUtils.isAlphaSpace("ab-c") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains letters and space, and is non-null

Since:

3.0 Changed signature from isAlphaSpace(String) to isAlphaSpace(CharSequence)

isAnyBlank

public static boolean isAnyBlank(CharSequence... css)

Checks if any of the CharSequences are empty ("") or null or whitespace only.

Whitespace is defined by Character.isWhitespace(char).

 StringUtils.isAnyBlank((String) null)    = true
 StringUtils.isAnyBlank((String[]) null)  = false
 StringUtils.isAnyBlank(null, "foo")      = true
 StringUtils.isAnyBlank(null, null)       = true
 StringUtils.isAnyBlank("", "bar")        = true
 StringUtils.isAnyBlank("bob", "")        = true
 StringUtils.isAnyBlank("  bob  ", null)  = true
 StringUtils.isAnyBlank(" ", "bar")       = true
 StringUtils.isAnyBlank(new String[] {})  = false
 StringUtils.isAnyBlank(new String[]{""}) = true
 StringUtils.isAnyBlank("foo", "bar")     = false

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if any of the CharSequences are empty or null or whitespace only
Since:: 3.2

isAnyEmpty

public static boolean isAnyEmpty(CharSequence... css)

Checks if any of the CharSequences are empty ("") or null.

 StringUtils.isAnyEmpty((String) null)    = true
 StringUtils.isAnyEmpty((String[]) null)  = false
 StringUtils.isAnyEmpty(null, "foo")      = true
 StringUtils.isAnyEmpty("", "bar")        = true
 StringUtils.isAnyEmpty("bob", "")        = true
 StringUtils.isAnyEmpty("  bob  ", null)  = true
 StringUtils.isAnyEmpty(" ", "bar")       = false
 StringUtils.isAnyEmpty("foo", "bar")     = false
 StringUtils.isAnyEmpty(new String[]{})   = false
 StringUtils.isAnyEmpty(new String[]{""}) = true

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if any of the CharSequences are empty or null
Since:: 3.2

isAsciiPrintable

public static boolean isAsciiPrintable(CharSequence cs)

Checks if the CharSequence contains only ASCII printable characters.

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isAsciiPrintable(null)     = false
 StringUtils.isAsciiPrintable("")       = true
 StringUtils.isAsciiPrintable(" ")      = true
 StringUtils.isAsciiPrintable("Ceki")   = true
 StringUtils.isAsciiPrintable("ab2c")   = true
 StringUtils.isAsciiPrintable("!ab-c~") = true
 StringUtils.isAsciiPrintable(" ") = true
 StringUtils.isAsciiPrintable("!") = true
 StringUtils.isAsciiPrintable("~") = true
 StringUtils.isAsciiPrintable("") = false
 StringUtils.isAsciiPrintable("Ceki Gülcü") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if every character is in the range 32 thru 126
Since:: 2.1, 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)

isBlank
```
public static boolean isBlank(CharSequence cs)
```
Checks if a CharSequence is empty (""), null or whitespace only.

Whitespace is defined by Character.isWhitespace(char).
```
 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is null, empty or whitespace only

Since:

2.0, 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)

isEmpty
```
public static boolean isEmpty(CharSequence cs)
```
Checks if a CharSequence is empty ("") or null.
```
 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false
 
```
NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is empty or null

Since:

3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)

isMixedCase

public static boolean isMixedCase(CharSequence cs)

Checks if the CharSequence contains mixed casing of both uppercase and lowercase characters.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isMixedCase(null)    = false
 StringUtils.isMixedCase("")      = false
 StringUtils.isMixedCase("ABC")   = false
 StringUtils.isMixedCase("abc")   = false
 StringUtils.isMixedCase("aBc")   = true
 StringUtils.isMixedCase("A c")   = true
 StringUtils.isMixedCase("A1c")   = true
 StringUtils.isMixedCase("a/C")   = true
 StringUtils.isMixedCase("aC\t")  = true

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence contains both uppercase and lowercase characters
Since:: 3.5

isNoneBlank

public static boolean isNoneBlank(CharSequence... css)

Checks if none of the CharSequences are empty (""), null or whitespace only.

Whitespace is defined by Character.isWhitespace(char).

 StringUtils.isNoneBlank((String) null)    = false
 StringUtils.isNoneBlank((String[]) null)  = true
 StringUtils.isNoneBlank(null, "foo")      = false
 StringUtils.isNoneBlank(null, null)       = false
 StringUtils.isNoneBlank("", "bar")        = false
 StringUtils.isNoneBlank("bob", "")        = false
 StringUtils.isNoneBlank("  bob  ", null)  = false
 StringUtils.isNoneBlank(" ", "bar")       = false
 StringUtils.isNoneBlank(new String[] {})  = true
 StringUtils.isNoneBlank(new String[]{""}) = false
 StringUtils.isNoneBlank("foo", "bar")     = true

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if none of the CharSequences are empty or null or whitespace only
Since:: 3.2

isNoneEmpty

public static boolean isNoneEmpty(CharSequence... css)

Checks if none of the CharSequences are empty ("") or null.

 StringUtils.isNoneEmpty((String) null)    = false
 StringUtils.isNoneEmpty((String[]) null)  = true
 StringUtils.isNoneEmpty(null, "foo")      = false
 StringUtils.isNoneEmpty("", "bar")        = false
 StringUtils.isNoneEmpty("bob", "")        = false
 StringUtils.isNoneEmpty("  bob  ", null)  = false
 StringUtils.isNoneEmpty(new String[] {})  = true
 StringUtils.isNoneEmpty(new String[]{""}) = false
 StringUtils.isNoneEmpty(" ", "bar")       = true
 StringUtils.isNoneEmpty("foo", "bar")     = true

Parameters:: css - the CharSequences to check, may be null or empty
Returns:: true if none of the CharSequences are empty or null
Since:: 3.2

isNotBlank
```
public static boolean isNotBlank(CharSequence cs)
```
Checks if a CharSequence is not empty (""), not null and not whitespace only.

Whitespace is defined by Character.isWhitespace(char).
```
 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if the CharSequence is not empty and not null and not whitespace only

Since:

2.0, 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)

isNotEmpty

public static boolean isNotEmpty(CharSequence cs)

Checks if a CharSequence is not empty ("") and not null.

 StringUtils.isNotEmpty(null)      = false
 StringUtils.isNotEmpty("")        = false
 StringUtils.isNotEmpty(" ")       = true
 StringUtils.isNotEmpty("bob")     = true
 StringUtils.isNotEmpty("  bob  ") = true

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence is not empty and not null
Since:: 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)

isNumeric
```
public static boolean isNumeric(CharSequence cs)
```
Checks if the CharSequence contains only Unicode digits. A decimal point is not a Unicode digit and returns false.

null will return false. An empty CharSequence (length()=0) will return false.

Note that the method does not allow for a leading sign, either positive or negative. Also, if a String passes the numeric test, it may still generate a NumberFormatException when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range for int or long respectively.
```
 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = false
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("१२३")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false
 StringUtils.isNumeric("-123") = false
 StringUtils.isNumeric("+123") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains digits, and is non-null

Since:

3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence), 3.0 Changed "" to return false and not true

isNumericSpace

public static boolean isNumericSpace(CharSequence cs)

Checks if the CharSequence contains only Unicode digits or space (' '). A decimal point is not a Unicode digit and returns false.

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isNumericSpace(null)   = false
 StringUtils.isNumericSpace("")     = true
 StringUtils.isNumericSpace("  ")   = true
 StringUtils.isNumericSpace("123")  = true
 StringUtils.isNumericSpace("12 3") = true
 StringUtils.isNumericSpace("१२३")  = true
 StringUtils.isNumericSpace("१२ ३")  = true
 StringUtils.isNumericSpace("ab2c") = false
 StringUtils.isNumericSpace("12-3") = false
 StringUtils.isNumericSpace("12.3") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains digits or space, and is non-null
Since:: 3.0 Changed signature from isNumericSpace(String) to isNumericSpace(CharSequence)

isWhitespace
```
public static boolean isWhitespace(CharSequence cs)
```
Checks if the CharSequence contains only whitespace.

Whitespace is defined by Character.isWhitespace(char).

null will return false. An empty CharSequence (length()=0) will return true.
```
 StringUtils.isWhitespace(null)   = false
 StringUtils.isWhitespace("")     = true
 StringUtils.isWhitespace("  ")   = true
 StringUtils.isWhitespace("abc")  = false
 StringUtils.isWhitespace("ab2c") = false
 StringUtils.isWhitespace("ab-c") = false
 
```
Parameters:

cs - the CharSequence to check, may be null

Returns:

true if only contains whitespace, and is non-null

Since:

2.0, 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence)

join
```
public static String join(boolean[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)              = null
 StringUtils.join([], *)                = ""
 StringUtils.join([null], *)            = ""
 StringUtils.join([false, false], ';')  = "false;false"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.12.0

join
```
public static String join(boolean[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)                   = null
 StringUtils.join([], *)                     = ""
 StringUtils.join([null], *)                 = ""
 StringUtils.join([true, false, true], ';')  = "true;false;true"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.12.0

join
```
public static String join(byte[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(byte[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(char[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(char[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(double[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(double[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(float[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(float[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(int[] array,
                          char separator)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(int[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(Iterable<?> iterable,
                          char separator)
```
Joins the elements of the provided Iterable into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:

iterable - the Iterable providing the values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null iterator input

Since:

2.3

join
```
public static String join(Iterable<?> iterable,
                          String separator)
```
Joins the elements of the provided Iterable into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:

iterable - the Iterable providing the values to join together, may be null

separator - the separator character to use, null treated as ""

Returns:

the joined String, null if null iterator input

Since:

2.3

join
```
public static String join(Iterator<?> iterator,
                          char separator)
```
Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:

iterator - the Iterator of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null iterator input

Since:

2.0

join
```
public static String join(Iterator<?> iterator,
                          String separator)
```
Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:

iterator - the Iterator of values to join together, may be null

separator - the separator character to use, null treated as ""

Returns:

the joined String, null if null iterator input

join
```
public static String join(List<?> list,
                          char separator,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided List into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

list - the List of values to join together, may be null

separator - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the list

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the list

Returns:

the joined String, null if null list input

Since:

3.8

join
```
public static String join(List<?> list,
                          String separator,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided List into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

list - the List of values to join together, may be null

separator - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the list

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the list

Returns:

the joined String, null if null list input

Since:

3.8

join
```
public static String join(long[] array,
                          char separator)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(long[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(Object[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

2.0

join
```
public static String join(Object[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

2.0

join

public static String join(Object[] array,
                          String delimiter)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"

Parameters:: array - the array of values to join together, may be null; delimiter - the separator character to use, null treated as ""
Returns:: the joined String, null if null array input

join
```
public static String join(Object[] array,
                          String delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *, *, *)                = null
 StringUtils.join([], *, *, *)                  = ""
 StringUtils.join([null], *, *, *)              = ""
 StringUtils.join(["a", "b", "c"], "--", 0, 3)  = "a--b--c"
 StringUtils.join(["a", "b", "c"], "--", 1, 3)  = "b--c"
 StringUtils.join(["a", "b", "c"], "--", 2, 3)  = "c"
 StringUtils.join(["a", "b", "c"], "--", 2, 2)  = ""
 StringUtils.join(["a", "b", "c"], null, 0, 3)  = "abc"
 StringUtils.join(["a", "b", "c"], "", 0, 3)    = "abc"
 StringUtils.join([null, "", "a"], ',', 0, 3)   = ",,a"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use, null treated as ""

startIndex - the first index to start joining from.

endIndex - the index to stop joining from (exclusive).

Returns:

the joined String, null if null array input; or the empty string if endIndex - startIndex <= 0. The number of joined entries is given by endIndex - startIndex

Throws:

ArrayIndexOutOfBoundsException - ife
startIndex < 0 or
startIndex >= array.length() or
endIndex < 0 or
endIndex > array.length()

join
```
public static String join(short[] array,
                          char delimiter)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

Returns:

the joined String, null if null array input

Since:

3.2

join
```
public static String join(short[] array,
                          char delimiter,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
Parameters:

array - the array of values to join together, may be null

delimiter - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in a start index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

3.2

join
```
@SafeVarargs
public static <T> String join(T... elements)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No separator is added to the joined String. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null)            = null
 StringUtils.join([])              = ""
 StringUtils.join([null])          = ""
 StringUtils.join(["a", "b", "c"]) = "abc"
 StringUtils.join([null, "", "a"]) = "a"
 
```
Type Parameters:

T - the specific type of values to join together

Parameters:

elements - the values to join together, may be null

Returns:

the joined String, null if null array input

Since:

2.0, 3.0 Changed signature to use varargs

joinWith
```
public static String joinWith(String delimiter,
                              Object... array)
```
Joins the elements of the provided varargs into a single String containing the provided elements.

No delimiter is added before or after the list. null elements and separator are treated as empty Strings ("").
```
 StringUtils.joinWith(",", {"a", "b"})        = "a,b"
 StringUtils.joinWith(",", {"a", "b",""})     = "a,b,"
 StringUtils.joinWith(",", {"a", null, "b"})  = "a,,b"
 StringUtils.joinWith(null, {"a", "b"})       = "ab"
 
```
Parameters:

delimiter - the separator character to use, null treated as ""

array - the varargs providing the values to join together. null elements are treated as ""

Returns:

the joined String.

Throws:

IllegalArgumentException - if a null varargs is provided

Since:

3.5

lastIndexOf

public static int lastIndexOf(CharSequence seq,
                              CharSequence searchSeq)

Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(String) if possible.

A null CharSequence will return -1.

 StringUtils.lastIndexOf(null, *)          = -1
 StringUtils.lastIndexOf(*, null)          = -1
 StringUtils.lastIndexOf("", "")           = 0
 StringUtils.lastIndexOf("aabaabaa", "a")  = 7
 StringUtils.lastIndexOf("aabaabaa", "b")  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab") = 4
 StringUtils.lastIndexOf("aabaabaa", "")   = 8

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null
Returns:: the last index of the search String, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from lastIndexOf(String, String) to lastIndexOf(CharSequence, CharSequence)

lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
                              CharSequence searchSeq,
                              int startPos)
```
Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(String, int) if possible.

A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
```
 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf(*, null, *)          = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
 StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
 StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
 StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", "b", 1)  = -1
 StringUtils.lastIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastIndexOf("aabaabaa", "ba", 2)  = 2
 
```
Parameters:

seq - the CharSequence to check, may be null

searchSeq - the CharSequence to find, may be null

startPos - the start position, negative treated as zero

Returns:

the last index of the search CharSequence (always ≤ startPos), -1 if no match or null string input

Since:

2.0, 3.0 Changed signature from lastIndexOf(String, String, int) to lastIndexOf(CharSequence, CharSequence, int)

lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
                              int searchChar)
```
Returns the index within seq of the last occurrence of the specified character. For values of searchChar in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest value k such that:
```
 this.charAt(k) == searchChar
 
```
is true. For other values of searchChar, it is the largest value k such that:
```
 this.codePointAt(k) == searchChar
 
```
is true. In either case, if no such character occurs in this string, then -1 is returned. Furthermore, a null or empty ("") CharSequence will return -1. The seq CharSequence object is searched backwards starting at the last character.
```
 StringUtils.lastIndexOf(null, *)         = -1
 StringUtils.lastIndexOf("", *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'a') = 7
 StringUtils.lastIndexOf("aabaabaa", 'b') = 5
 
```
Parameters:

seq - the CharSequence to check, may be null

searchChar - the character to find

Returns:

the last index of the search character, -1 if no match or null string input

Since:

2.0, 3.0 Changed signature from lastIndexOf(String, int) to lastIndexOf(CharSequence, int), 3.6 Updated CharSequenceUtils call to behave more like String

lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
                              int searchChar,
                              int startPos)
```
Returns the index within seq of the last occurrence of the specified character, searching backward starting at the specified index. For values of searchChar in the range from 0 to 0xFFFF (inclusive), the index returned is the largest value k such that:
```
 (this.charAt(k) == searchChar) && (k <= startPos)
 
```
is true. For other values of searchChar, it is the largest value k such that:
```
 (this.codePointAt(k) == searchChar) && (k <= startPos)
 
```
is true. In either case, if no such character occurs in seq at or before position startPos, then -1 is returned. Furthermore, a null or empty ("") CharSequence will return -1. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
All indices are specified in char values (Unicode code units).
```
 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf("", *,  *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
 StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
 StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0
 
```
Parameters:

seq - the CharSequence to check, may be null

searchChar - the character to find

startPos - the start position

Returns:

the last index of the search character (always ≤ startPos), -1 if no match or null string input

Since:

2.0, 3.0 Changed signature from lastIndexOf(String, int, int) to lastIndexOf(CharSequence, int, int)

lastIndexOfAny

public static int lastIndexOfAny(CharSequence str,
                                 CharSequence... searchStrs)

Find the latest index of any substring in a set of potential substrings.

A null CharSequence will return -1. A null search array will return -1. A null or zero length search array entry will be ignored, but a search array containing "" will return the length of str if str is not null. This method uses String.indexOf(String) if possible

 StringUtils.lastIndexOfAny(null, *)                    = -1
 StringUtils.lastIndexOfAny(*, null)                    = -1
 StringUtils.lastIndexOfAny(*, [])                      = -1
 StringUtils.lastIndexOfAny(*, [null])                  = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["ab", "cd"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["cd", "ab"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", "op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", "op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn", ""])   = 10

Parameters:: str - the CharSequence to check, may be null; searchStrs - the CharSequences to search for, may be null
Returns:: the last index of any of the CharSequences, -1 if no match
Since:: 3.0 Changed signature from lastIndexOfAny(String, String[]) to lastIndexOfAny(CharSequence, CharSequence)

lastIndexOfIgnoreCase
```
public static int lastIndexOfIgnoreCase(CharSequence str,
                                        CharSequence searchStr)
```
Case in-sensitive find of the last index within a CharSequence.

A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string.
```
 StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4
 
```
Parameters:

str - the CharSequence to check, may be null

searchStr - the CharSequence to find, may be null

Returns:

the first index of the search CharSequence, -1 if no match or null string input

Since:

2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String) to lastIndexOfIgnoreCase(CharSequence, CharSequence)

lastIndexOfIgnoreCase
```
public static int lastIndexOfIgnoreCase(CharSequence str,
                                        CharSequence searchStr,
                                        int startPos)
```
Case in-sensitive find of the last index within a CharSequence from the specified position.

A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
```
 StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1
 
```
Parameters:

str - the CharSequence to check, may be null

searchStr - the CharSequence to find, may be null

startPos - the start position

Returns:

the last index of the search CharSequence (always ≤ startPos), -1 if no match or null input

Since:

2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String, int) to lastIndexOfIgnoreCase(CharSequence, CharSequence, int)

lastOrdinalIndexOf

public static int lastOrdinalIndexOf(CharSequence str,
                                     CharSequence searchStr,
                                     int ordinal)

Finds the n-th last index within a String, handling null. This method uses String.lastIndexOf(String).

A null String will return -1.

 StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
 StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
 StringUtils.lastOrdinalIndexOf("", "", *)           = 0
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8

Note that 'tail(CharSequence str, int n)' may be implemented as:

   str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; ordinal - the n-th last searchStr to find
Returns:: the n-th last index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
Since:: 2.5, 3.0 Changed signature from lastOrdinalIndexOf(String, String, int) to lastOrdinalIndexOf(CharSequence, CharSequence, int)

left
```
public static String left(String str,
                          int len)
```
Gets the leftmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.
```
 StringUtils.left(null, *)    = null
 StringUtils.left(*, -ve)     = ""
 StringUtils.left("", *)      = ""
 StringUtils.left("abc", 0)   = ""
 StringUtils.left("abc", 2)   = "ab"
 StringUtils.left("abc", 4)   = "abc"
 
```
Parameters:

str - the String to get the leftmost characters from, may be null

len - the length of the required String

Returns:

the leftmost characters, null if null String input

leftPad

public static String leftPad(String str,
                             int size)

Left pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.leftPad(null, *)   = null
 StringUtils.leftPad("", 3)     = "   "
 StringUtils.leftPad("bat", 3)  = "bat"
 StringUtils.leftPad("bat", 5)  = "  bat"
 StringUtils.leftPad("bat", 1)  = "bat"
 StringUtils.leftPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: left padded String or original String if no padding is necessary, null if null String input

leftPad

public static String leftPad(String str,
                             int size,
                             char padChar)

Left pad a String with a specified character.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)     = null
 StringUtils.leftPad("", 3, 'z')     = "zzz"
 StringUtils.leftPad("bat", 3, 'z')  = "bat"
 StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
 StringUtils.leftPad("bat", 1, 'z')  = "bat"
 StringUtils.leftPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: left padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

leftPad

public static String leftPad(String str,
                             int size,
                             String padStr)

Left pad a String with a specified String.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)      = null
 StringUtils.leftPad("", 3, "z")      = "zzz"
 StringUtils.leftPad("bat", 3, "yz")  = "bat"
 StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
 StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
 StringUtils.leftPad("bat", 1, "yz")  = "bat"
 StringUtils.leftPad("bat", -1, "yz") = "bat"
 StringUtils.leftPad("bat", 5, null)  = "  bat"
 StringUtils.leftPad("bat", 5, "")    = "  bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: left padded String or original String if no padding is necessary, null if null String input

length
```
public static int length(CharSequence cs)
```
Gets a CharSequence length or 0 if the CharSequence is null.

Parameters:

cs - a CharSequence or null

Returns:

CharSequence length or 0 if the CharSequence is null.

Since:

2.4, 3.0 Changed signature from length(String) to length(CharSequence)

lowerCase
```
public static String lowerCase(String str)
```
Converts a String to lower case as per String.toLowerCase().

A null input String returns null.
```
 StringUtils.lowerCase(null)  = null
 StringUtils.lowerCase("")    = ""
 StringUtils.lowerCase("aBc") = "abc"
 
```
Note: As described in the documentation for String.toLowerCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
Parameters:

str - the String to lower case, may be null

Returns:

the lower cased String, null if null String input

lowerCase
```
public static String lowerCase(String str,
                               Locale locale)
```
Converts a String to lower case as per String.toLowerCase(Locale).

A null input String returns null.
```
 StringUtils.lowerCase(null, Locale.ENGLISH)  = null
 StringUtils.lowerCase("", Locale.ENGLISH)    = ""
 StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc"
 
```
Parameters:

str - the String to lower case, may be null

locale - the locale that defines the case transformation rules, must not be null

Returns:

the lower cased String, null if null String input

Since:

2.5

mid
```
public static String mid(String str,
                         int pos,
                         int len)
```
Gets len characters from the middle of a String.

If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An empty String is returned if len is negative or exceeds the length of str.
```
 StringUtils.mid(null, *, *)    = null
 StringUtils.mid(*, *, -ve)     = ""
 StringUtils.mid("", 0, *)      = ""
 StringUtils.mid("abc", 0, 2)   = "ab"
 StringUtils.mid("abc", 0, 4)   = "abc"
 StringUtils.mid("abc", 2, 4)   = "c"
 StringUtils.mid("abc", 4, 2)   = ""
 StringUtils.mid("abc", -2, 2)  = "ab"
 
```
Parameters:

str - the String to get the characters from, may be null

pos - the position to start from, negative treated as zero

len - the length of the required String

Returns:

the middle characters, null if null String input

normalizeSpace
```
public static String normalizeSpace(String str)
```
Similar to http://www.w3.org/TR/xpath/#function-normalize -space

The function returns the argument string with whitespace normalized by using {@link #trim(String)} to remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.
In XML Whitespace characters are the same as those allowed by the S production, which is S ::= (#x20 | #x9 | #xD | #xA)+
Java's regexp pattern \s defines whitespace as [ \t\n\x0B\f\r]
For reference:
- \x0B = vertical tab
- \f = #xC = form feed
- #x20 = space
- #x9 = \t
- #xA = \n
- #xD = \r
The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also normalize. Additionally {@link #trim(String)} removes control characters (char <= 32) from both ends of this String.
Parameters:

str - the source String to normalize whitespaces from, may be null

Returns:

the modified string with whitespace normalized, null if null String input

Since:

3.0

See Also:

Pattern, trim(String), http://www.w3.org/TR/xpath/#function-normalize-space

ordinalIndexOf

public static int ordinalIndexOf(CharSequence str,
                                 CharSequence searchStr,
                                 int ordinal)

Finds the n-th index within a CharSequence, handling null. This method uses String.indexOf(String) if possible.

Note: The code starts looking for a match at the start of the target, incrementing the starting index by one after each successful match (unless searchStr is an empty string in which case the position is never incremented and 0 is returned immediately). This means that matches may overlap.

A null CharSequence will return -1.

 StringUtils.ordinalIndexOf(null, *, *)          = -1
 StringUtils.ordinalIndexOf(*, null, *)          = -1
 StringUtils.ordinalIndexOf("", "", *)           = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
 StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
 StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
 StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
 StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0

Matches may overlap:

 StringUtils.ordinalIndexOf("ababab", "aba", 1)   = 0
 StringUtils.ordinalIndexOf("ababab", "aba", 2)   = 2
 StringUtils.ordinalIndexOf("ababab", "aba", 3)   = -1

 StringUtils.ordinalIndexOf("abababab", "abab", 1) = 0
 StringUtils.ordinalIndexOf("abababab", "abab", 2) = 2
 StringUtils.ordinalIndexOf("abababab", "abab", 3) = 4
 StringUtils.ordinalIndexOf("abababab", "abab", 4) = -1

Note that 'head(CharSequence str, int n)' may be implemented as:

   str.substring(0, lastOrdinalIndexOf(str, "\n", n))

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; ordinal - the n-th searchStr to find
Returns:: the n-th index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
Since:: 2.1, 3.0 Changed signature from ordinalIndexOf(String, String, int) to ordinalIndexOf(CharSequence, CharSequence, int)

overlay

public static String overlay(String str,
                             String overlay,
                             int start,
                             int end)

Overlays part of a String with another String.

A null string input returns null. A negative index is treated as zero. An index greater than the string length is treated as the string length. The start index is always the smaller of the two indices.

 StringUtils.overlay(null, *, *, *)            = null
 StringUtils.overlay("", "abc", 0, 0)          = "abc"
 StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
 StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
 StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
 StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
 StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
 StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
 StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"

Parameters:: str - the String to do overlaying in, may be null; overlay - the String to overlay, may be null; start - the position to start overlaying at; end - the position to stop overlaying before
Returns:: overlayed String, null if null String input
Since:: 2.0

prependIfMissing

public static String prependIfMissing(String str,
                                      CharSequence prefix,
                                      CharSequence... prefixes)

Prepends the prefix to the start of the string if the string does not already start with any of the prefixes.

 StringUtils.prependIfMissing(null, null) = null
 StringUtils.prependIfMissing("abc", null) = "abc"
 StringUtils.prependIfMissing("", "xyz") = "xyz"
 StringUtils.prependIfMissing("abc", "xyz") = "xyzabc"
 StringUtils.prependIfMissing("xyzabc", "xyz") = "xyzabc"
 StringUtils.prependIfMissing("XYZabc", "xyz") = "xyzXYZabc"

With additional prefixes,

 StringUtils.prependIfMissing(null, null, null) = null
 StringUtils.prependIfMissing("abc", null, null) = "abc"
 StringUtils.prependIfMissing("", "xyz", null) = "xyz"
 StringUtils.prependIfMissing("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
 StringUtils.prependIfMissing("abc", "xyz", "") = "abc"
 StringUtils.prependIfMissing("abc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissing("xyzabc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissing("mnoabc", "xyz", "mno") = "mnoabc"
 StringUtils.prependIfMissing("XYZabc", "xyz", "mno") = "xyzXYZabc"
 StringUtils.prependIfMissing("MNOabc", "xyz", "mno") = "xyzMNOabc"

Parameters:: str - The string.; prefix - The prefix to prepend to the start of the string.; prefixes - Additional prefixes that are valid.
Returns:: A new String if prefix was prepended, the same string otherwise.
Since:: 3.2

prependIfMissingIgnoreCase

public static String prependIfMissingIgnoreCase(String str,
                                                CharSequence prefix,
                                                CharSequence... prefixes)

Prepends the prefix to the start of the string if the string does not already start, case insensitive, with any of the prefixes.

 StringUtils.prependIfMissingIgnoreCase(null, null) = null
 StringUtils.prependIfMissingIgnoreCase("abc", null) = "abc"
 StringUtils.prependIfMissingIgnoreCase("", "xyz") = "xyz"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz") = "XYZabc"

With additional prefixes,

 StringUtils.prependIfMissingIgnoreCase(null, null, null) = null
 StringUtils.prependIfMissingIgnoreCase("abc", null, null) = "abc"
 StringUtils.prependIfMissingIgnoreCase("", "xyz", null) = "xyz"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "") = "abc"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("mnoabc", "xyz", "mno") = "mnoabc"
 StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz", "mno") = "XYZabc"
 StringUtils.prependIfMissingIgnoreCase("MNOabc", "xyz", "mno") = "MNOabc"

Parameters:: str - The string.; prefix - The prefix to prepend to the start of the string.; prefixes - Additional prefixes that are valid (optional).
Returns:: A new String if prefix was prepended, the same string otherwise.
Since:: 3.2

remove
```
public static String remove(String str,
                            char remove)
```
Removes all occurrences of a character from within the source string.

A null source string will return null. An empty ("") source string will return the empty string.
```
 StringUtils.remove(null, *)       = null
 StringUtils.remove("", *)         = ""
 StringUtils.remove("queued", 'u') = "qeed"
 StringUtils.remove("queued", 'z') = "queued"
 
```
Parameters:

str - the source String to search, may be null

remove - the char to search for and remove, may be null

Returns:

the substring with the char removed if found, null if null String input

Since:

2.1

remove
```
public static String remove(String str,
                            String remove)
```
Removes all occurrences of a substring from within the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.
```
 StringUtils.remove(null, *)        = null
 StringUtils.remove("", *)          = ""
 StringUtils.remove(*, null)        = *
 StringUtils.remove(*, "")          = *
 StringUtils.remove("queued", "ue") = "qd"
 StringUtils.remove("queued", "zz") = "queued"
 
```
Parameters:

str - the source String to search, may be null

remove - the String to search for and remove, may be null

Returns:

the substring with the string removed if found, null if null String input

Since:

2.1

removeAll
```
@Deprecated
public static String removeAll(String text,
                                           String regex)
```
Deprecated. Moved to RegExUtils.
Removes each substring of the text String that matches the given regular expression.
This method is a null safe equivalent to:
- text.replaceAll(regex, StringUtils.EMPTY)
- Pattern.compile(regex).matcher(text).replaceAll(StringUtils.EMPTY)
A null reference passed to this method is a no-op.

Unlike in the removePattern(String, String) method, the Pattern.DOTALL option is NOT automatically added. To use the DOTALL option prepend "(?s)" to the regex. DOTALL is also known as single-line mode in Perl.
```
 StringUtils.removeAll(null, *)      = null
 StringUtils.removeAll("any", (String) null)  = "any"
 StringUtils.removeAll("any", "")    = "any"
 StringUtils.removeAll("any", ".*")  = ""
 StringUtils.removeAll("any", ".+")  = ""
 StringUtils.removeAll("abc", ".?")  = ""
 StringUtils.removeAll("A<__>\n<__>B", "<.*>")      = "A\nB"
 StringUtils.removeAll("A<__>\n<__>B", "(?s)<.*>")  = "AB"
 StringUtils.removeAll("ABCabc123abc", "[a-z]")     = "ABC123"
 
```
Parameters:

text - text to remove from, may be null

regex - the regular expression to which this string is to be matched

Returns:

the text with any removes processed, null if null String input

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Since:

3.5

See Also:

replaceAll(String, String, String), removePattern(String, String), String.replaceAll(String, String), Pattern, Pattern.DOTALL

removeEnd

public static String removeEnd(String str,
                               String remove)

Removes a substring only if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEnd(null, *)      = null
 StringUtils.removeEnd("", *)        = ""
 StringUtils.removeEnd(*, null)      = *
 StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEnd("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeEndIgnoreCase

public static String removeEndIgnoreCase(String str,
                                         String remove)

Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEndIgnoreCase(null, *)      = null
 StringUtils.removeEndIgnoreCase("", *)        = ""
 StringUtils.removeEndIgnoreCase(*, null)      = *
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
 StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

removeFirst
```
@Deprecated
public static String removeFirst(String text,
                                             String regex)
```
Deprecated. Moved to RegExUtils.
Removes the first substring of the text string that matches the given regular expression.
This method is a null safe equivalent to:
- text.replaceFirst(regex, StringUtils.EMPTY)
- Pattern.compile(regex).matcher(text).replaceFirst(StringUtils.EMPTY)
A null reference passed to this method is a no-op.

The Pattern.DOTALL option is NOT automatically added. To use the DOTALL option prepend "(?s)" to the regex. DOTALL is also known as single-line mode in Perl.
```
 StringUtils.removeFirst(null, *)      = null
 StringUtils.removeFirst("any", (String) null)  = "any"
 StringUtils.removeFirst("any", "")    = "any"
 StringUtils.removeFirst("any", ".*")  = ""
 StringUtils.removeFirst("any", ".+")  = ""
 StringUtils.removeFirst("abc", ".?")  = "bc"
 StringUtils.removeFirst("A<__>\n<__>B", "<.*>")      = "A\n<__>B"
 StringUtils.removeFirst("A<__>\n<__>B", "(?s)<.*>")  = "AB"
 StringUtils.removeFirst("ABCabc123", "[a-z]")          = "ABCbc123"
 StringUtils.removeFirst("ABCabc123abc", "[a-z]+")      = "ABC123abc"
 
```
Parameters:

text - text to remove from, may be null

regex - the regular expression to which this string is to be matched

Returns:

the text with the first replacement processed, null if null String input

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Since:

3.5

See Also:

replaceFirst(String, String, String), String.replaceFirst(String, String), Pattern, Pattern.DOTALL

removeIgnoreCase

public static String removeIgnoreCase(String str,
                                      String remove)

Case insensitive removal of all occurrences of a substring from within the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.

 StringUtils.removeIgnoreCase(null, *)        = null
 StringUtils.removeIgnoreCase("", *)          = ""
 StringUtils.removeIgnoreCase(*, null)        = *
 StringUtils.removeIgnoreCase(*, "")          = *
 StringUtils.removeIgnoreCase("queued", "ue") = "qd"
 StringUtils.removeIgnoreCase("queued", "zz") = "queued"
 StringUtils.removeIgnoreCase("quEUed", "UE") = "qd"
 StringUtils.removeIgnoreCase("queued", "zZ") = "queued"

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 3.5

removePattern
```
@Deprecated
public static String removePattern(String source,
                                               String regex)
```
Deprecated. Moved to RegExUtils.
Removes each substring of the source String that matches the given regular expression using the DOTALL option.
This call is a null safe equivalent to:
- source.replaceAll("(?s)" + regex, StringUtils.EMPTY)
- Pattern.compile(regex, Pattern.DOTALL).matcher(source).replaceAll(StringUtils.EMPTY)
A null reference passed to this method is a no-op.
```
 StringUtils.removePattern(null, *)       = null
 StringUtils.removePattern("any", (String) null)   = "any"
 StringUtils.removePattern("A<__>\n<__>B", "<.*>")  = "AB"
 StringUtils.removePattern("ABCabc123", "[a-z]")    = "ABC123"
 
```
Parameters:

source - the source string

regex - the regular expression to which this string is to be matched

Returns:

The resulting String

Since:

3.2, 3.5 Changed null reference passed to this method is a no-op.

See Also:

replacePattern(String, String, String), String.replaceAll(String, String), Pattern.DOTALL

removeStart

public static String removeStart(String str,
                                 String remove)

Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStart(null, *)      = null
 StringUtils.removeStart("", *)        = ""
 StringUtils.removeStart(*, null)      = *
 StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStart("domain.com", "www.")       = "domain.com"
 StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStart("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeStartIgnoreCase

public static String removeStartIgnoreCase(String str,
                                           String remove)

Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStartIgnoreCase(null, *)      = null
 StringUtils.removeStartIgnoreCase("", *)        = ""
 StringUtils.removeStartIgnoreCase(*, null)      = *
 StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStartIgnoreCase("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

repeat
```
public static String repeat(char ch,
                            int repeat)
```
Returns padding using the specified delimiter repeated to a given length.
```
 StringUtils.repeat('e', 0)  = ""
 StringUtils.repeat('e', 3)  = "eee"
 StringUtils.repeat('e', -2) = ""
 
```
Note: this method does not support padding with Unicode Supplementary Characters as they require a pair of chars to be represented. If you are needing to support full I18N of your applications consider using repeat(String, int) instead.
Parameters:

ch - character to repeat

repeat - number of times to repeat char, negative treated as zero

Returns:

String with repeated character

See Also:

repeat(String, int)

repeat

public static String repeat(String str,
                            int repeat)

Repeat a String repeat times to form a new String.

 StringUtils.repeat(null, 2) = null
 StringUtils.repeat("", 0)   = ""
 StringUtils.repeat("", 2)   = ""
 StringUtils.repeat("a", 3)  = "aaa"
 StringUtils.repeat("ab", 2) = "abab"
 StringUtils.repeat("a", -2) = ""

Parameters:: str - the String to repeat, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input

repeat

public static String repeat(String str,
                            String separator,
                            int repeat)

Repeat a String repeat times to form a new String, with a String separator injected each time.

 StringUtils.repeat(null, null, 2) = null
 StringUtils.repeat(null, "x", 2)  = null
 StringUtils.repeat("", null, 0)   = ""
 StringUtils.repeat("", "", 2)     = ""
 StringUtils.repeat("", "x", 3)    = "xxx"
 StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"

Parameters:: str - the String to repeat, may be null; separator - the String to inject, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input
Since:: 2.5

replace

public static String replace(String text,
                             String searchString,
                             String replacement)

Replaces all occurrences of a String within another String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *)        = null
 StringUtils.replace("", *, *)          = ""
 StringUtils.replace("any", null, *)    = "any"
 StringUtils.replace("any", *, null)    = "any"
 StringUtils.replace("any", "", *)      = "any"
 StringUtils.replace("aba", "a", null)  = "aba"
 StringUtils.replace("aba", "a", "")    = "b"
 StringUtils.replace("aba", "a", "z")   = "zbz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replace

public static String replace(String text,
                             String searchString,
                             String replacement,
                             int max)

Replaces a String with another String inside a larger String, for the first max values of the search String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *, *)         = null
 StringUtils.replace("", *, *, *)           = ""
 StringUtils.replace("any", null, *, *)     = "any"
 StringUtils.replace("any", *, null, *)     = "any"
 StringUtils.replace("any", "", *, *)       = "any"
 StringUtils.replace("any", *, *, 0)        = "any"
 StringUtils.replace("abaa", "a", null, -1) = "abaa"
 StringUtils.replace("abaa", "a", "", -1)   = "b"
 StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
 StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
 StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null; max - maximum number of values to replace, or -1 if no maximum
Returns:: the text with any replacements processed, null if null String input

replaceAll

@Deprecated
public static String replaceAll(String text,
                                            String regex,
                                            String replacement)

Deprecated. Moved to RegExUtils.

Replaces each substring of the text String that matches the given regular expression with the given replacement.

This method is a null safe equivalent to:

text.replaceAll(regex, replacement)
Pattern.compile(regex).matcher(text).replaceAll(replacement)

A null reference passed to this method is a no-op.

Unlike in the replacePattern(String, String, String) method, the Pattern.DOTALL option is NOT automatically added. To use the DOTALL option prepend "(?s)" to the regex. DOTALL is also known as single-line mode in Perl.

 StringUtils.replaceAll(null, *, *)       = null
 StringUtils.replaceAll("any", (String) null, *)   = "any"
 StringUtils.replaceAll("any", *, null)   = "any"
 StringUtils.replaceAll("", "", "zzz")    = "zzz"
 StringUtils.replaceAll("", ".*", "zzz")  = "zzz"
 StringUtils.replaceAll("", ".+", "zzz")  = ""
 StringUtils.replaceAll("abc", "", "ZZ")  = "ZZaZZbZZcZZ"
 StringUtils.replaceAll("<__>\n<__>", "<.*>", "z")      = "z\nz"
 StringUtils.replaceAll("<__>\n<__>", "(?s)<.*>", "z")  = "z"
 StringUtils.replaceAll("ABCabc123", "[a-z]", "_")       = "ABC___123"
 StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "_")  = "ABC_123"
 StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "")   = "ABC123"
 StringUtils.replaceAll("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum_dolor_sit"

Parameters:: text - text to search and replace in, may be null; regex - the regular expression to which this string is to be matched; replacement - the string to be substituted for each match
Returns:: the text with any replacements processed, null if null String input
Throws:: PatternSyntaxException - if the regular expression's syntax is invalid
Since:: 3.5
See Also:: replacePattern(String, String, String), String.replaceAll(String, String), Pattern, Pattern.DOTALL

replaceChars
```
public static String replaceChars(String str,
                                  char searchChar,
                                  char replaceChar)
```
Replaces all occurrences of a character in a String with another. This is a null-safe version of String.replace(char, char).

A null string input returns null. An empty ("") string input returns an empty string.
```
 StringUtils.replaceChars(null, *, *)        = null
 StringUtils.replaceChars("", *, *)          = ""
 StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
 StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
 
```
Parameters:

str - String to replace characters in, may be null

searchChar - the character to search for, may be null

replaceChar - the character to replace, may be null

Returns:

modified String, null if null string input

Since:

2.0

replaceChars
```
public static String replaceChars(String str,
                                  String searchChars,
                                  String replaceChars)
```
Replaces multiple characters in a String in one go. This method can also be used to delete characters.

For example:
replaceChars("hello", "ho", "jy") = jelly.

A null string input returns null. An empty ("") string input returns an empty string. A null or empty set of search characters returns the input string.

The length of the search characters should normally equal the length of the replace characters. If the search characters is longer, then the extra search characters are deleted. If the search characters is shorter, then the extra replace characters are ignored.
```
 StringUtils.replaceChars(null, *, *)           = null
 StringUtils.replaceChars("", *, *)             = ""
 StringUtils.replaceChars("abc", null, *)       = "abc"
 StringUtils.replaceChars("abc", "", *)         = "abc"
 StringUtils.replaceChars("abc", "b", null)     = "ac"
 StringUtils.replaceChars("abc", "b", "")       = "ac"
 StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
 StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
 StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
 
```
Parameters:

str - String to replace characters in, may be null

searchChars - a set of characters to search for, may be null

replaceChars - a set of characters to replace, may be null

Returns:

modified String, null if null string input

Since:

2.0

replaceEach

public static String replaceEach(String text,
                                 String[] searchList,
                                 String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

  StringUtils.replaceEach(null, *, *)        = null
  StringUtils.replaceEach("", *, *)          = ""
  StringUtils.replaceEach("aba", null, null) = "aba"
  StringUtils.replaceEach("aba", new String[0], null) = "aba"
  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
  (example of how it does not repeat)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceEachRepeatedly

public static String replaceEachRepeatedly(String text,
                                           String[] searchList,
                                           String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored.

  StringUtils.replaceEachRepeatedly(null, *, *) = null
  StringUtils.replaceEachRepeatedly("", *, *) = ""
  StringUtils.replaceEachRepeatedly("aba", null, null) = "aba"
  StringUtils.replaceEachRepeatedly("aba", new String[0], null) = "aba"
  StringUtils.replaceEachRepeatedly("aba", null, new String[0]) = "aba"
  StringUtils.replaceEachRepeatedly("aba", new String[]{"a"}, null) = "aba"
  StringUtils.replaceEachRepeatedly("aba", new String[]{"a"}, new String[]{""}) = "b"
  StringUtils.replaceEachRepeatedly("aba", new String[]{null}, new String[]{"a"}) = "aba"
  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}) = "wcte"
  (example of how it repeats)
  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}) = "tcte"
  StringUtils.replaceEachRepeatedly("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}) = IllegalStateException

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IllegalStateException - if the search is repeating and there is an endless loop due to outputs of one being inputs to another; IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceFirst

@Deprecated
public static String replaceFirst(String text,
                                              String regex,
                                              String replacement)

Deprecated. Moved to RegExUtils.

Replaces the first substring of the text string that matches the given regular expression with the given replacement.

This method is a null safe equivalent to:

text.replaceFirst(regex, replacement)
Pattern.compile(regex).matcher(text).replaceFirst(replacement)

A null reference passed to this method is a no-op.

The Pattern.DOTALL option is NOT automatically added. To use the DOTALL option prepend "(?s)" to the regex. DOTALL is also known as single-line mode in Perl.

 StringUtils.replaceFirst(null, *, *)       = null
 StringUtils.replaceFirst("any", (String) null, *)   = "any"
 StringUtils.replaceFirst("any", *, null)   = "any"
 StringUtils.replaceFirst("", "", "zzz")    = "zzz"
 StringUtils.replaceFirst("", ".*", "zzz")  = "zzz"
 StringUtils.replaceFirst("", ".+", "zzz")  = ""
 StringUtils.replaceFirst("abc", "", "ZZ")  = "ZZabc"
 StringUtils.replaceFirst("<__>\n<__>", "<.*>", "z")      = "z\n<__>"
 StringUtils.replaceFirst("<__>\n<__>", "(?s)<.*>", "z")  = "z"
 StringUtils.replaceFirst("ABCabc123", "[a-z]", "_")          = "ABC_bc123"
 StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "_")  = "ABC_123abc"
 StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "")   = "ABC123abc"
 StringUtils.replaceFirst("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum  dolor   sit"

Parameters:: text - text to search and replace in, may be null; regex - the regular expression to which this string is to be matched; replacement - the string to be substituted for the first match
Returns:: the text with the first replacement processed, null if null String input
Throws:: PatternSyntaxException - if the regular expression's syntax is invalid
Since:: 3.5
See Also:: String.replaceFirst(String, String), Pattern, Pattern.DOTALL

replaceIgnoreCase

public static String replaceIgnoreCase(String text,
                                       String searchString,
                                       String replacement)

Case insensitively replaces all occurrences of a String within another String.

A null reference passed to this method is a no-op.

 StringUtils.replaceIgnoreCase(null, *, *)        = null
 StringUtils.replaceIgnoreCase("", *, *)          = ""
 StringUtils.replaceIgnoreCase("any", null, *)    = "any"
 StringUtils.replaceIgnoreCase("any", *, null)    = "any"
 StringUtils.replaceIgnoreCase("any", "", *)      = "any"
 StringUtils.replaceIgnoreCase("aba", "a", null)  = "aba"
 StringUtils.replaceIgnoreCase("abA", "A", "")    = "b"
 StringUtils.replaceIgnoreCase("aba", "A", "z")   = "zbz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for (case insensitive), may be null; replacement - the String to replace it with, may be null
Returns:: the text with any replacements processed, null if null String input
Since:: 3.5
See Also:: replaceIgnoreCase(String text, String searchString, String replacement, int max)

replaceIgnoreCase

public static String replaceIgnoreCase(String text,
                                       String searchString,
                                       String replacement,
                                       int max)

Case insensitively replaces a String with another String inside a larger String, for the first max values of the search String.

A null reference passed to this method is a no-op.

 StringUtils.replaceIgnoreCase(null, *, *, *)         = null
 StringUtils.replaceIgnoreCase("", *, *, *)           = ""
 StringUtils.replaceIgnoreCase("any", null, *, *)     = "any"
 StringUtils.replaceIgnoreCase("any", *, null, *)     = "any"
 StringUtils.replaceIgnoreCase("any", "", *, *)       = "any"
 StringUtils.replaceIgnoreCase("any", *, *, 0)        = "any"
 StringUtils.replaceIgnoreCase("abaa", "a", null, -1) = "abaa"
 StringUtils.replaceIgnoreCase("abaa", "a", "", -1)   = "b"
 StringUtils.replaceIgnoreCase("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replaceIgnoreCase("abaa", "A", "z", 1)   = "zbaa"
 StringUtils.replaceIgnoreCase("abAa", "a", "z", 2)   = "zbza"
 StringUtils.replaceIgnoreCase("abAa", "a", "z", -1)  = "zbzz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for (case insensitive), may be null; replacement - the String to replace it with, may be null; max - maximum number of values to replace, or -1 if no maximum
Returns:: the text with any replacements processed, null if null String input
Since:: 3.5

replaceOnce

public static String replaceOnce(String text,
                                 String searchString,
                                 String replacement)

Replaces a String with another String inside a larger String, once.

A null reference passed to this method is a no-op.

 StringUtils.replaceOnce(null, *, *)        = null
 StringUtils.replaceOnce("", *, *)          = ""
 StringUtils.replaceOnce("any", null, *)    = "any"
 StringUtils.replaceOnce("any", *, null)    = "any"
 StringUtils.replaceOnce("any", "", *)      = "any"
 StringUtils.replaceOnce("aba", "a", null)  = "aba"
 StringUtils.replaceOnce("aba", "a", "")    = "ba"
 StringUtils.replaceOnce("aba", "a", "z")   = "zba"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replaceOnceIgnoreCase

public static String replaceOnceIgnoreCase(String text,
                                           String searchString,
                                           String replacement)

Case insensitively replaces a String with another String inside a larger String, once.

A null reference passed to this method is a no-op.

 StringUtils.replaceOnceIgnoreCase(null, *, *)        = null
 StringUtils.replaceOnceIgnoreCase("", *, *)          = ""
 StringUtils.replaceOnceIgnoreCase("any", null, *)    = "any"
 StringUtils.replaceOnceIgnoreCase("any", *, null)    = "any"
 StringUtils.replaceOnceIgnoreCase("any", "", *)      = "any"
 StringUtils.replaceOnceIgnoreCase("aba", "a", null)  = "aba"
 StringUtils.replaceOnceIgnoreCase("aba", "a", "")    = "ba"
 StringUtils.replaceOnceIgnoreCase("aba", "a", "z")   = "zba"
 StringUtils.replaceOnceIgnoreCase("FoOFoofoo", "foo", "") = "Foofoo"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for (case insensitive), may be null; replacement - the String to replace with, may be null
Returns:: the text with any replacements processed, null if null String input
Since:: 3.5
See Also:: replaceIgnoreCase(String text, String searchString, String replacement, int max)

replacePattern

@Deprecated
public static String replacePattern(String source,
                                                String regex,
                                                String replacement)

Deprecated. Moved to RegExUtils.

Replaces each substring of the source String that matches the given regular expression with the given replacement using the Pattern.DOTALL option. DOTALL is also known as single-line mode in Perl.

This call is a null safe equivalent to:

source.replaceAll("(?s)" + regex, replacement)
Pattern.compile(regex, Pattern.DOTALL).matcher(source).replaceAll(replacement)

A null reference passed to this method is a no-op.

 StringUtils.replacePattern(null, *, *)       = null
 StringUtils.replacePattern("any", (String) null, *)   = "any"
 StringUtils.replacePattern("any", *, null)   = "any"
 StringUtils.replacePattern("", "", "zzz")    = "zzz"
 StringUtils.replacePattern("", ".*", "zzz")  = "zzz"
 StringUtils.replacePattern("", ".+", "zzz")  = ""
 StringUtils.replacePattern("<__>\n<__>", "<.*>", "z")       = "z"
 StringUtils.replacePattern("ABCabc123", "[a-z]", "_")       = "ABC___123"
 StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "_")  = "ABC_123"
 StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "")   = "ABC123"
 StringUtils.replacePattern("Lorem ipsum  dolor   sit", "( +)([a-z]+)", "_$2")  = "Lorem_ipsum_dolor_sit"

Parameters:: source - the source string; regex - the regular expression to which this string is to be matched; replacement - the string to be substituted for each match
Returns:: The resulting String
Since:: 3.2, 3.5 Changed null reference passed to this method is a no-op.
See Also:: replaceAll(String, String, String), String.replaceAll(String, String), Pattern.DOTALL

reverse
```
public static String reverse(String str)
```
Reverses a String as per StringBuilder.reverse().

A null String returns null.
```
 StringUtils.reverse(null)  = null
 StringUtils.reverse("")    = ""
 StringUtils.reverse("bat") = "tab"
 
```
Parameters:

str - the String to reverse, may be null

Returns:

the reversed String, null if null String input

reverseDelimited
```
public static String reverseDelimited(String str,
                                      char separatorChar)
```
Reverses a String that is delimited by a specific character.

The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is '.').
```
 StringUtils.reverseDelimited(null, *)      = null
 StringUtils.reverseDelimited("", *)        = ""
 StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
 StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
 
```
Parameters:

str - the String to reverse, may be null

separatorChar - the separator character to use

Returns:

the reversed String, null if null String input

Since:

2.0

right
```
public static String right(String str,
                           int len)
```
Gets the rightmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an an exception. An empty String is returned if len is negative.
```
 StringUtils.right(null, *)    = null
 StringUtils.right(*, -ve)     = ""
 StringUtils.right("", *)      = ""
 StringUtils.right("abc", 0)   = ""
 StringUtils.right("abc", 2)   = "bc"
 StringUtils.right("abc", 4)   = "abc"
 
```
Parameters:

str - the String to get the rightmost characters from, may be null

len - the length of the required String

Returns:

the rightmost characters, null if null String input

rightPad

public static String rightPad(String str,
                              int size)

Right pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.rightPad(null, *)   = null
 StringUtils.rightPad("", 3)     = "   "
 StringUtils.rightPad("bat", 3)  = "bat"
 StringUtils.rightPad("bat", 5)  = "bat  "
 StringUtils.rightPad("bat", 1)  = "bat"
 StringUtils.rightPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: right padded String or original String if no padding is necessary, null if null String input

rightPad

public static String rightPad(String str,
                              int size,
                              char padChar)

Right pad a String with a specified character.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)     = null
 StringUtils.rightPad("", 3, 'z')     = "zzz"
 StringUtils.rightPad("bat", 3, 'z')  = "bat"
 StringUtils.rightPad("bat", 5, 'z')  = "batzz"
 StringUtils.rightPad("bat", 1, 'z')  = "bat"
 StringUtils.rightPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: right padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

rightPad

public static String rightPad(String str,
                              int size,
                              String padStr)

Right pad a String with a specified String.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)      = null
 StringUtils.rightPad("", 3, "z")      = "zzz"
 StringUtils.rightPad("bat", 3, "yz")  = "bat"
 StringUtils.rightPad("bat", 5, "yz")  = "batyz"
 StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
 StringUtils.rightPad("bat", 1, "yz")  = "bat"
 StringUtils.rightPad("bat", -1, "yz") = "bat"
 StringUtils.rightPad("bat", 5, null)  = "bat  "
 StringUtils.rightPad("bat", 5, "")    = "bat  "

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: right padded String or original String if no padding is necessary, null if null String input

rotate

public static String rotate(String str,
                            int shift)

Rotate (circular shift) a String of shift characters.

If shift > 0, right circular shift (ex : ABCDEF => FABCDE)
If shift < 0, left circular shift (ex : ABCDEF => BCDEFA)

 StringUtils.rotate(null, *)        = null
 StringUtils.rotate("", *)          = ""
 StringUtils.rotate("abcdefg", 0)   = "abcdefg"
 StringUtils.rotate("abcdefg", 2)   = "fgabcde"
 StringUtils.rotate("abcdefg", -2)  = "cdefgab"
 StringUtils.rotate("abcdefg", 7)   = "abcdefg"
 StringUtils.rotate("abcdefg", -7)  = "abcdefg"
 StringUtils.rotate("abcdefg", 9)   = "fgabcde"
 StringUtils.rotate("abcdefg", -9)  = "cdefgab"

Parameters:: str - the String to rotate, may be null; shift - number of time to shift (positive : right shift, negative : left shift)
Returns:: the rotated String, or the original String if shift == 0, or null if null String input
Since:: 3.5

split
```
public static String[] split(String str)
```
Splits the provided text into an array, using whitespace as the separator. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.split(null)       = null
 StringUtils.split("")         = []
 StringUtils.split("abc def")  = ["abc", "def"]
 StringUtils.split("abc  def") = ["abc", "def"]
 StringUtils.split(" abc ")    = ["abc"]
 
```
Parameters:

str - the String to parse, may be null

Returns:

an array of parsed Strings, null if null String input

split
```
public static String[] split(String str,
                             char separatorChar)
```
Splits the provided text into an array, separator specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
 StringUtils.split("a:b:c", '.')    = ["a:b:c"]
 StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
 
```
Parameters:

str - the String to parse, may be null

separatorChar - the character used as the delimiter

Returns:

an array of parsed Strings, null if null String input

Since:

2.0

split
```
public static String[] split(String str,
                             String separatorChars)
```
Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("abc def", null) = ["abc", "def"]
 StringUtils.split("abc def", " ")  = ["abc", "def"]
 StringUtils.split("abc  def", " ") = ["abc", "def"]
 StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
 
```
Parameters:

str - the String to parse, may be null

separatorChars - the characters used as the delimiters, null splits on whitespace

Returns:

an array of parsed Strings, null if null String input

split
```
public static String[] split(String str,
                             String separatorChars,
                             int max)
```
Splits the provided text into an array with a maximum length, separators specified.

The separator is not included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).
```
 StringUtils.split(null, *, *)            = null
 StringUtils.split("", *, *)              = []
 StringUtils.split("ab cd ef", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.split("ab   cd ef", null, 0) = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 
```
Parameters:

str - the String to parse, may be null

separatorChars - the characters used as the delimiters, null splits on whitespace

max - the maximum number of elements to include in the array. A zero or negative value implies no limit

Returns:

an array of parsed Strings, null if null String input

splitByCharacterType

public static String[] splitByCharacterType(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens.

 StringUtils.splitByCharacterType(null)         = null
 StringUtils.splitByCharacterType("")           = []
 StringUtils.splitByCharacterType("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterType("number5")    = ["number", "5"]
 StringUtils.splitByCharacterType("fooBar")     = ["foo", "B", "ar"]
 StringUtils.splitByCharacterType("foo200Bar")  = ["foo", "200", "B", "ar"]
 StringUtils.splitByCharacterType("ASFRules")   = ["ASFR", "ules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

splitByCharacterTypeCamelCase

public static String[] splitByCharacterTypeCamelCase(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens, with the following exception: the character of type Character.UPPERCASE_LETTER, if any, immediately preceding a token of type Character.LOWERCASE_LETTER will belong to the following token rather than to the preceding, if any, Character.UPPERCASE_LETTER token.

 StringUtils.splitByCharacterTypeCamelCase(null)         = null
 StringUtils.splitByCharacterTypeCamelCase("")           = []
 StringUtils.splitByCharacterTypeCamelCase("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterTypeCamelCase("number5")    = ["number", "5"]
 StringUtils.splitByCharacterTypeCamelCase("fooBar")     = ["foo", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("foo200Bar")  = ["foo", "200", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("ASFRules")   = ["ASF", "Rules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator)

Splits the provided text into an array, separator string specified.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *)               = null
 StringUtils.splitByWholeSeparator("", *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator,
                                             int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *, *)               = null
 StringUtils.splitByWholeSeparator("", *, *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator)

Splits the provided text into an array, separator string specified.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator,
                                                              int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str)
```
Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.splitPreserveAllTokens(null)       = null
 StringUtils.splitPreserveAllTokens("")         = []
 StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
 StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]
 
```
Parameters:

str - the String to parse, may be null

Returns:

an array of parsed Strings, null if null String input

Since:

2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              char separatorChar)

Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.splitPreserveAllTokens(null, *)         = null
 StringUtils.splitPreserveAllTokens("", *)           = []
 StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
 StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
 StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
 StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
 StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
 StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
 StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]

Parameters:: str - the String to parse, may be null; separatorChar - the character used as the delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars)

Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.

 StringUtils.splitPreserveAllTokens(null, *)           = null
 StringUtils.splitPreserveAllTokens("", *)             = []
 StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
 StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
 StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
 StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars,
                                              int max)

Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

 StringUtils.splitPreserveAllTokens(null, *, *)            = null
 StringUtils.splitPreserveAllTokens("", *, *)              = []
 StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "de", "fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "", "", "de", "fg"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace; max - the maximum number of elements to include in the array. A zero or negative value implies no limit
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

startsWith
```
public static boolean startsWith(CharSequence str,
                                 CharSequence prefix)
```
Check if a CharSequence starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.startsWith(null, null)      = true
 StringUtils.startsWith(null, "abc")     = false
 StringUtils.startsWith("abcdef", null)  = false
 StringUtils.startsWith("abcdef", "abc") = true
 StringUtils.startsWith("ABCDEF", "abc") = false
 
```
Parameters:

str - the CharSequence to check, may be null

prefix - the prefix to find, may be null

Returns:

true if the CharSequence starts with the prefix, case sensitive, or both null

Since:

2.4, 3.0 Changed signature from startsWith(String, String) to startsWith(CharSequence, CharSequence)

See Also:

String.startsWith(String)

startsWithAny

public static boolean startsWithAny(CharSequence sequence,
                                    CharSequence... searchStrings)

Check if a CharSequence starts with any of the provided case-sensitive prefixes.

 StringUtils.startsWithAny(null, null)      = false
 StringUtils.startsWithAny(null, new String[] {"abc"})  = false
 StringUtils.startsWithAny("abcxyz", null)     = false
 StringUtils.startsWithAny("abcxyz", new String[] {""}) = true
 StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
 StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
 StringUtils.startsWithAny("abcxyz", null, "xyz", "ABCX") = false
 StringUtils.startsWithAny("ABCXYZ", null, "xyz", "abc") = false

Parameters:: sequence - the CharSequence to check, may be null; searchStrings - the case-sensitive CharSequence prefixes, may be empty or contain null
Returns:: true if the input sequence is null AND no searchStrings are provided, or the input sequence begins with any of the provided case-sensitive searchStrings.
Since:: 2.5, 3.0 Changed signature from startsWithAny(String, String[]) to startsWithAny(CharSequence, CharSequence...)
See Also:: startsWith(CharSequence, CharSequence)

startsWithIgnoreCase
```
public static boolean startsWithIgnoreCase(CharSequence str,
                                           CharSequence prefix)
```
Case insensitive check if a CharSequence starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.
```
 StringUtils.startsWithIgnoreCase(null, null)      = true
 StringUtils.startsWithIgnoreCase(null, "abc")     = false
 StringUtils.startsWithIgnoreCase("abcdef", null)  = false
 StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
 StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true
 
```
Parameters:

str - the CharSequence to check, may be null

prefix - the prefix to find, may be null

Returns:

true if the CharSequence starts with the prefix, case insensitive, or both null

Since:

2.4, 3.0 Changed signature from startsWithIgnoreCase(String, String) to startsWithIgnoreCase(CharSequence, CharSequence)

See Also:

String.startsWith(String)

strip

public static String strip(String str)

Strips whitespace from the start and end of a String.

This is similar to trim(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

A null input String returns null.

 StringUtils.strip(null)     = null
 StringUtils.strip("")       = ""
 StringUtils.strip("   ")    = ""
 StringUtils.strip("abc")    = "abc"
 StringUtils.strip("  abc")  = "abc"
 StringUtils.strip("abc  ")  = "abc"
 StringUtils.strip(" abc ")  = "abc"
 StringUtils.strip(" ab c ") = "ab c"

Parameters:: str - the String to remove whitespace from, may be null
Returns:: the stripped String, null if null String input

strip
```
public static String strip(String str,
                           String stripChars)
```
Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char). Alternatively use strip(String).
```
 StringUtils.strip(null, *)          = null
 StringUtils.strip("", *)            = ""
 StringUtils.strip("abc", null)      = "abc"
 StringUtils.strip("  abc", null)    = "abc"
 StringUtils.strip("abc  ", null)    = "abc"
 StringUtils.strip(" abc ", null)    = "abc"
 StringUtils.strip("  abcyx", "xyz") = "  abc"
 
```
Parameters:

str - the String to remove characters from, may be null

stripChars - the characters to remove, null treated as whitespace

Returns:

the stripped String, null if null String input

stripAccents

public static String stripAccents(String input)

Removes diacritics (~= accents) from a string. The case will not be altered.

For instance, 'à' will be replaced by 'a'.

Note that ligatures will be left as is.

 StringUtils.stripAccents(null)                = null
 StringUtils.stripAccents("")                  = ""
 StringUtils.stripAccents("control")           = "control"
 StringUtils.stripAccents("éclair")     = "eclair"

Parameters:: input - String to be stripped
Returns:: input text with diacritics removed
Since:: 3.0

stripAll
```
public static String[] stripAll(String... strs)
```
Strips whitespace from the start and end of every String in an array. Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored.
```
 StringUtils.stripAll(null)             = null
 StringUtils.stripAll([])               = []
 StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null])  = ["abc", null]
 
```
Parameters:

strs - the array to remove whitespace from, may be null

Returns:

the stripped Strings, null if null array input

stripAll
```
public static String[] stripAll(String[] strs,
                                String stripChars)
```
Strips any of a set of characters from the start and end of every String in an array.

Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored. A null stripChars will strip whitespace as defined by Character.isWhitespace(char).
```
 StringUtils.stripAll(null, *)                = null
 StringUtils.stripAll([], *)                  = []
 StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
 StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
 StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
 
```
Parameters:

strs - the array to remove characters from, may be null

stripChars - the characters to remove, null treated as whitespace

Returns:

the stripped Strings, null if null array input

stripEnd

public static String stripEnd(String str,
                              String stripChars)

Strips any of a set of characters from the end of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripEnd(null, *)          = null
 StringUtils.stripEnd("", *)            = ""
 StringUtils.stripEnd("abc", "")        = "abc"
 StringUtils.stripEnd("abc", null)      = "abc"
 StringUtils.stripEnd("  abc", null)    = "  abc"
 StringUtils.stripEnd("abc  ", null)    = "abc"
 StringUtils.stripEnd(" abc ", null)    = " abc"
 StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
 StringUtils.stripEnd("120.00", ".0")   = "12"

Parameters:: str - the String to remove characters from, may be null; stripChars - the set of characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripStart

public static String stripStart(String str,
                                String stripChars)

Strips any of a set of characters from the start of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripStart(null, *)          = null
 StringUtils.stripStart("", *)            = ""
 StringUtils.stripStart("abc", "")        = "abc"
 StringUtils.stripStart("abc", null)      = "abc"
 StringUtils.stripStart("  abc", null)    = "abc"
 StringUtils.stripStart("abc  ", null)    = "abc  "
 StringUtils.stripStart(" abc ", null)    = "abc "
 StringUtils.stripStart("yxabc  ", "xyz") = "abc  "

Parameters:: str - the String to remove characters from, may be null; stripChars - the characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripToEmpty

public static String stripToEmpty(String str)

Strips whitespace from the start and end of a String returning an empty String if null input.

This is similar to trimToEmpty(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToEmpty(null)     = ""
 StringUtils.stripToEmpty("")       = ""
 StringUtils.stripToEmpty("   ")    = ""
 StringUtils.stripToEmpty("abc")    = "abc"
 StringUtils.stripToEmpty("  abc")  = "abc"
 StringUtils.stripToEmpty("abc  ")  = "abc"
 StringUtils.stripToEmpty(" abc ")  = "abc"
 StringUtils.stripToEmpty(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the trimmed String, or an empty String if null input
Since:: 2.0

stripToNull

public static String stripToNull(String str)

Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.

This is similar to trimToNull(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToNull(null)     = null
 StringUtils.stripToNull("")       = null
 StringUtils.stripToNull("   ")    = null
 StringUtils.stripToNull("abc")    = "abc"
 StringUtils.stripToNull("  abc")  = "abc"
 StringUtils.stripToNull("abc  ")  = "abc"
 StringUtils.stripToNull(" abc ")  = "abc"
 StringUtils.stripToNull(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the stripped String, null if whitespace, empty or null String input
Since:: 2.0

substring
```
public static String substring(String str,
                               int start)
```
Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start n characters from the end of the String.

A null String will return null. An empty ("") String will return "".
```
 StringUtils.substring(null, *)   = null
 StringUtils.substring("", *)     = ""
 StringUtils.substring("abc", 0)  = "abc"
 StringUtils.substring("abc", 2)  = "c"
 StringUtils.substring("abc", 4)  = ""
 StringUtils.substring("abc", -2) = "bc"
 StringUtils.substring("abc", -4) = "abc"
 
```
Parameters:

str - the String to get the substring from, may be null

start - the position to start from, negative means count back from the end of the String by this many characters

Returns:

substring from start position, null if null String input

substring
```
public static String substring(String str,
                               int start,
                               int end)
```
Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start/end n characters from the end of the String.

The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.

If start is not strictly to the left of end, "" is returned.
```
 StringUtils.substring(null, *, *)    = null
 StringUtils.substring("", * ,  *)    = "";
 StringUtils.substring("abc", 0, 2)   = "ab"
 StringUtils.substring("abc", 2, 0)   = ""
 StringUtils.substring("abc", 2, 4)   = "c"
 StringUtils.substring("abc", 4, 6)   = ""
 StringUtils.substring("abc", 2, 2)   = ""
 StringUtils.substring("abc", -2, -1) = "b"
 StringUtils.substring("abc", -4, 2)  = "ab"
 
```
Parameters:

str - the String to get the substring from, may be null

start - the position to start from, negative means count back from the end of the String by this many characters

end - the position to end at (exclusive), negative means count back from the end of the String by this many characters

Returns:

substring from start position to end position, null if null String input

substringAfter

public static String substringAfter(String str,
                                    int separator)

Gets the substring after the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string.

If nothing is found, the empty string is returned.

 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter("abc", 'a')   = "bc"
 StringUtils.substringAfter("abcba", 'b') = "cba"
 StringUtils.substringAfter("abc", 'c')   = ""
 StringUtils.substringAfter("abc", 'd')   = ""
 StringUtils.substringAfter(" abc", 32)   = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the character to search.
Returns:: the substring after the first occurrence of the separator, null if null String input
Since:: 3.11

substringAfter

public static String substringAfter(String str,
                                    String separator)

Gets the substring after the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter(*, null)      = ""
 StringUtils.substringAfter("abc", "a")   = "bc"
 StringUtils.substringAfter("abcba", "b") = "cba"
 StringUtils.substringAfter("abc", "c")   = ""
 StringUtils.substringAfter("abc", "d")   = ""
 StringUtils.substringAfter("abc", "")    = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the first occurrence of the separator, null if null String input
Since:: 2.0

substringAfterLast

public static String substringAfterLast(String str,
                                        int separator)

Gets the substring after the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string.

If nothing is found, the empty string is returned.

 StringUtils.substringAfterLast(null, *)      = null
 StringUtils.substringAfterLast("", *)        = ""
 StringUtils.substringAfterLast("abc", 'a')   = "bc"
 StringUtils.substringAfterLast(" bc", 32)    = "bc"
 StringUtils.substringAfterLast("abcba", 'b') = "a"
 StringUtils.substringAfterLast("abc", 'c')   = ""
 StringUtils.substringAfterLast("a", 'a')     = ""
 StringUtils.substringAfterLast("a", 'z')     = ""

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the last occurrence of the separator, null if null String input
Since:: 3.11

substringAfterLast

public static String substringAfterLast(String str,
                                        String separator)

Gets the substring after the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfterLast(null, *)      = null
 StringUtils.substringAfterLast("", *)        = ""
 StringUtils.substringAfterLast(*, "")        = ""
 StringUtils.substringAfterLast(*, null)      = ""
 StringUtils.substringAfterLast("abc", "a")   = "bc"
 StringUtils.substringAfterLast("abcba", "b") = "a"
 StringUtils.substringAfterLast("abc", "c")   = ""
 StringUtils.substringAfterLast("a", "a")     = ""
 StringUtils.substringAfterLast("a", "z")     = ""

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the last occurrence of the separator, null if null String input
Since:: 2.0

substringBefore
```
public static String substringBefore(String str,
                                     int separator)
```
Gets the substring before the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string.

If nothing is found, the string input is returned.
```
 StringUtils.substringBefore(null, *)      = null
 StringUtils.substringBefore("", *)        = ""
 StringUtils.substringBefore("abc", 'a')   = ""
 StringUtils.substringBefore("abcba", 'b') = "a"
 StringUtils.substringBefore("abc", 'c')   = "ab"
 StringUtils.substringBefore("abc", 'd')   = "abc"
 
```
Parameters:

str - the String to get a substring from, may be null

separator - the String to search for, may be null

Returns:

the substring before the first occurrence of the separator, null if null String input

Since:

3.12.0

substringBefore

public static String substringBefore(String str,
                                     String separator)

Gets the substring before the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBefore(null, *)      = null
 StringUtils.substringBefore("", *)        = ""
 StringUtils.substringBefore("abc", "a")   = ""
 StringUtils.substringBefore("abcba", "b") = "a"
 StringUtils.substringBefore("abc", "c")   = "ab"
 StringUtils.substringBefore("abc", "d")   = "abc"
 StringUtils.substringBefore("abc", "")    = ""
 StringUtils.substringBefore("abc", null)  = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the first occurrence of the separator, null if null String input
Since:: 2.0

substringBeforeLast

public static String substringBeforeLast(String str,
                                         String separator)

Gets the substring before the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBeforeLast(null, *)      = null
 StringUtils.substringBeforeLast("", *)        = ""
 StringUtils.substringBeforeLast("abcba", "b") = "abc"
 StringUtils.substringBeforeLast("abc", "c")   = "ab"
 StringUtils.substringBeforeLast("a", "a")     = ""
 StringUtils.substringBeforeLast("a", "z")     = "a"
 StringUtils.substringBeforeLast("a", null)    = "a"
 StringUtils.substringBeforeLast("a", "")      = "a"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the last occurrence of the separator, null if null String input
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String tag)

Gets the String that is nested in between two instances of the same String.

A null input String returns null. A null tag returns null.

 StringUtils.substringBetween(null, *)            = null
 StringUtils.substringBetween("", "")             = ""
 StringUtils.substringBetween("", "tag")          = null
 StringUtils.substringBetween("tagabctag", null)  = null
 StringUtils.substringBetween("tagabctag", "")    = ""
 StringUtils.substringBetween("tagabctag", "tag") = "abc"

Parameters:: str - the String containing the substring, may be null; tag - the String before and after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String open,
                                      String close)

Gets the String that is nested in between two Strings. Only the first match is returned.

A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.

 StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
 StringUtils.substringBetween(null, *, *)          = null
 StringUtils.substringBetween(*, null, *)          = null
 StringUtils.substringBetween(*, *, null)          = null
 StringUtils.substringBetween("", "", "")          = ""
 StringUtils.substringBetween("", "", "]")         = null
 StringUtils.substringBetween("", "[", "]")        = null
 StringUtils.substringBetween("yabcz", "", "")     = ""
 StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
 StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"

Parameters:: str - the String containing the substring, may be null; open - the String before the substring, may be null; close - the String after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringsBetween

public static String[] substringsBetween(String str,
                                         String open,
                                         String close)

Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns null (no match).

 StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
 StringUtils.substringsBetween(null, *, *)            = null
 StringUtils.substringsBetween(*, null, *)            = null
 StringUtils.substringsBetween(*, *, null)            = null
 StringUtils.substringsBetween("", "[", "]")          = []

Parameters:: str - the String containing the substrings, null returns null, empty returns empty; open - the String identifying the start of the substring, empty returns null; close - the String identifying the end of the substring, empty returns null
Returns:: a String Array of substrings, or null if no match
Since:: 2.3

swapCase
```
public static String swapCase(String str)
```
Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.
- Upper case character converts to Lower case
- Title case character converts to Lower case
- Lower case character converts to Upper case
For a word based algorithm, see WordUtils.swapCase(String). A null input String returns null.
```
 StringUtils.swapCase(null)                 = null
 StringUtils.swapCase("")                   = ""
 StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
 
```
NOTE: This method changed in Lang version 2.0. It no longer performs a word based algorithm. If you only use ASCII, you will notice no change. That functionality is available in org.apache.commons.lang3.text.WordUtils.
Parameters:

str - the String to swap case, may be null

Returns:

the changed String, null if null String input

toCodePoints
```
public static int[] toCodePoints(CharSequence cs)
```
Converts a CharSequence into an array of code points.

Valid pairs of surrogate code units will be converted into a single supplementary code point. Isolated surrogate code units (i.e. a high surrogate not followed by a low surrogate or a low surrogate not preceded by a high surrogate) will be returned as-is.
```
 StringUtils.toCodePoints(null)   =  null
 StringUtils.toCodePoints("")     =  []  // empty array
 
```
Parameters:

cs - the character sequence to convert

Returns:

an array of code points

Since:

3.6

toEncodedString
```
public static String toEncodedString(byte[] bytes,
                                     Charset charset)
```
Converts a byte[] to a String using the specified character encoding.

Parameters:

bytes - the byte array to read from

charset - the encoding to use, if null then use the platform default

Returns:

a new String

Throws:

NullPointerException - if bytes is null

Since:

3.2, 3.3 No longer throws UnsupportedEncodingException.

toRootLowerCase
```
public static String toRootLowerCase(String source)
```
Converts the given source String as a lower-case using the Locale.ROOT locale in a null-safe manner.

Parameters:

source - A source String or null.

Returns:

the given source String as a lower-case using the Locale.ROOT locale or null.

Since:

3.10

toRootUpperCase
```
public static String toRootUpperCase(String source)
```
Converts the given source String as a upper-case using the Locale.ROOT locale in a null-safe manner.

Parameters:

source - A source String or null.

Returns:

the given source String as a upper-case using the Locale.ROOT locale or null.

Since:

3.10

toString
```
@Deprecated
public static String toString(byte[] bytes,
                                          String charsetName)
                                   throws UnsupportedEncodingException
```
Deprecated. use toEncodedString(byte[], Charset) instead of String constants in your code

Converts a byte[] to a String using the specified character encoding.

Parameters:

bytes - the byte array to read from

charsetName - the encoding to use, if null then use the platform default

Returns:

a new String

Throws:

UnsupportedEncodingException - If the named charset is not supported

NullPointerException - if the input is null

Since:

3.1

trim
```
public static String trim(String str)
```
Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use strip(String).

To trim your choice of characters, use the strip(String, String) methods.
```
 StringUtils.trim(null)          = null
 StringUtils.trim("")            = ""
 StringUtils.trim("     ")       = ""
 StringUtils.trim("abc")         = "abc"
 StringUtils.trim("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed string, null if null String input

trimToEmpty
```
public static String trimToEmpty(String str)
```
Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.
The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToEmpty(String).
```
 StringUtils.trimToEmpty(null)          = ""
 StringUtils.trimToEmpty("")            = ""
 StringUtils.trimToEmpty("     ")       = ""
 StringUtils.trimToEmpty("abc")         = "abc"
 StringUtils.trimToEmpty("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, or an empty String if null input

Since:

2.0

trimToNull
```
public static String trimToNull(String str)
```
Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.
The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToNull(String).
```
 StringUtils.trimToNull(null)          = null
 StringUtils.trimToNull("")            = null
 StringUtils.trimToNull("     ")       = null
 StringUtils.trimToNull("abc")         = "abc"
 StringUtils.trimToNull("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, null if only chars <= 32, empty or null String input

Since:

2.0

truncate
```
public static String truncate(String str,
                              int maxWidth)
```
Truncates a String. This will turn "Now is the time for all good men" into "Now is the time for".

Specifically:
- If str is less than maxWidth characters long, return it.
- Else truncate it to substring(str, 0, maxWidth).
- If maxWidth is less than 0, throw an IllegalArgumentException.
- In no case will it return a String of length greater than maxWidth.
```
 StringUtils.truncate(null, 0)       = null
 StringUtils.truncate(null, 2)       = null
 StringUtils.truncate("", 4)         = ""
 StringUtils.truncate("abcdefg", 4)  = "abcd"
 StringUtils.truncate("abcdefg", 6)  = "abcdef"
 StringUtils.truncate("abcdefg", 7)  = "abcdefg"
 StringUtils.truncate("abcdefg", 8)  = "abcdefg"
 StringUtils.truncate("abcdefg", -1) = throws an IllegalArgumentException
 
```
Parameters:

str - the String to truncate, may be null

maxWidth - maximum length of result String, must be positive

Returns:

truncated String, null if null String input

Throws:

IllegalArgumentException - If maxWidth is less than 0

Since:

3.5

truncate

public static String truncate(String str,
                              int offset,
                              int maxWidth)

Truncates a String. This will turn "Now is the time for all good men" into "is the time for all".

Works like truncate(String, int), but allows you to specify a "left edge" offset.

Specifically:

If str is less than maxWidth characters long, return it.
Else truncate it to substring(str, offset, maxWidth).
If maxWidth is less than 0, throw an IllegalArgumentException.
If offset is less than 0, throw an IllegalArgumentException.
In no case will it return a String of length greater than maxWidth.

 StringUtils.truncate(null, 0, 0) = null
 StringUtils.truncate(null, 2, 4) = null
 StringUtils.truncate("", 0, 10) = ""
 StringUtils.truncate("", 2, 10) = ""
 StringUtils.truncate("abcdefghij", 0, 3) = "abc"
 StringUtils.truncate("abcdefghij", 5, 6) = "fghij"
 StringUtils.truncate("raspberry peach", 10, 15) = "peach"
 StringUtils.truncate("abcdefghijklmno", 0, 10) = "abcdefghij"
 StringUtils.truncate("abcdefghijklmno", -1, 10) = throws an IllegalArgumentException
 StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, 10) = throws an IllegalArgumentException
 StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, Integer.MAX_VALUE) = throws an IllegalArgumentException
 StringUtils.truncate("abcdefghijklmno", 0, Integer.MAX_VALUE) = "abcdefghijklmno"
 StringUtils.truncate("abcdefghijklmno", 1, 10) = "bcdefghijk"
 StringUtils.truncate("abcdefghijklmno", 2, 10) = "cdefghijkl"
 StringUtils.truncate("abcdefghijklmno", 3, 10) = "defghijklm"
 StringUtils.truncate("abcdefghijklmno", 4, 10) = "efghijklmn"
 StringUtils.truncate("abcdefghijklmno", 5, 10) = "fghijklmno"
 StringUtils.truncate("abcdefghijklmno", 5, 5) = "fghij"
 StringUtils.truncate("abcdefghijklmno", 5, 3) = "fgh"
 StringUtils.truncate("abcdefghijklmno", 10, 3) = "klm"
 StringUtils.truncate("abcdefghijklmno", 10, Integer.MAX_VALUE) = "klmno"
 StringUtils.truncate("abcdefghijklmno", 13, 1) = "n"
 StringUtils.truncate("abcdefghijklmno", 13, Integer.MAX_VALUE) = "no"
 StringUtils.truncate("abcdefghijklmno", 14, 1) = "o"
 StringUtils.truncate("abcdefghijklmno", 14, Integer.MAX_VALUE) = "o"
 StringUtils.truncate("abcdefghijklmno", 15, 1) = ""
 StringUtils.truncate("abcdefghijklmno", 15, Integer.MAX_VALUE) = ""
 StringUtils.truncate("abcdefghijklmno", Integer.MAX_VALUE, Integer.MAX_VALUE) = ""
 StringUtils.truncate("abcdefghij", 3, -1) = throws an IllegalArgumentException
 StringUtils.truncate("abcdefghij", -2, 4) = throws an IllegalArgumentException

Parameters:: str - the String to truncate, may be null; offset - left edge of source String; maxWidth - maximum length of result String, must be positive
Returns:: truncated String, null if null String input
Throws:: IllegalArgumentException - If offset or maxWidth is less than 0
Since:: 3.5

uncapitalize
```
public static String uncapitalize(String str)
```
Uncapitalizes a String, changing the first character to lower case as per Character.toLowerCase(int). No other characters are changed.

For a word based algorithm, see WordUtils.uncapitalize(String). A null input String returns null.
```
 StringUtils.uncapitalize(null)  = null
 StringUtils.uncapitalize("")    = ""
 StringUtils.uncapitalize("cat") = "cat"
 StringUtils.uncapitalize("Cat") = "cat"
 StringUtils.uncapitalize("CAT") = "cAT"
 
```
Parameters:

str - the String to uncapitalize, may be null

Returns:

the uncapitalized String, null if null String input

Since:

2.0

See Also:

WordUtils.uncapitalize(String), capitalize(String)

unwrap

public static String unwrap(String str,
                            char wrapChar)

Unwraps a given string from a character.

 StringUtils.unwrap(null, null)         = null
 StringUtils.unwrap(null, '\0')         = null
 StringUtils.unwrap(null, '1')          = null
 StringUtils.unwrap("a", 'a')           = "a"
 StringUtils.unwrap("aa", 'a')           = ""
 StringUtils.unwrap("\'abc\'", '\'')    = "abc"
 StringUtils.unwrap("AABabcBAA", 'A')   = "ABabcBA"
 StringUtils.unwrap("A", '#')           = "A"
 StringUtils.unwrap("#A", '#')          = "#A"
 StringUtils.unwrap("A#", '#')          = "A#"

Parameters:: str - the String to be unwrapped, can be null; wrapChar - the character used to unwrap
Returns:: unwrapped String or the original string if it is not quoted properly with the wrapChar
Since:: 3.6

unwrap

public static String unwrap(String str,
                            String wrapToken)

Unwraps a given string from anther string.

 StringUtils.unwrap(null, null)         = null
 StringUtils.unwrap(null, "")           = null
 StringUtils.unwrap(null, "1")          = null
 StringUtils.unwrap("a", "a")           = "a"
 StringUtils.unwrap("aa", "a")          = ""
 StringUtils.unwrap("\'abc\'", "\'")    = "abc"
 StringUtils.unwrap("\"abc\"", "\"")    = "abc"
 StringUtils.unwrap("AABabcBAA", "AA")  = "BabcB"
 StringUtils.unwrap("A", "#")           = "A"
 StringUtils.unwrap("#A", "#")          = "#A"
 StringUtils.unwrap("A#", "#")          = "A#"

Parameters:: str - the String to be unwrapped, can be null; wrapToken - the String used to unwrap
Returns:: unwrapped String or the original string if it is not quoted properly with the wrapToken
Since:: 3.6

upperCase
```
public static String upperCase(String str)
```
Converts a String to upper case as per String.toUpperCase().

A null input String returns null.
```
 StringUtils.upperCase(null)  = null
 StringUtils.upperCase("")    = ""
 StringUtils.upperCase("aBc") = "ABC"
 
```
Note: As described in the documentation for String.toUpperCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
Parameters:

str - the String to upper case, may be null

Returns:

the upper cased String, null if null String input

upperCase
```
public static String upperCase(String str,
                               Locale locale)
```
Converts a String to upper case as per String.toUpperCase(Locale).

A null input String returns null.
```
 StringUtils.upperCase(null, Locale.ENGLISH)  = null
 StringUtils.upperCase("", Locale.ENGLISH)    = ""
 StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC"
 
```
Parameters:

str - the String to upper case, may be null

locale - the locale that defines the case transformation rules, must not be null

Returns:

the upper cased String, null if null String input

Since:

2.5

valueOf
```
public static String valueOf(char[] value)
```
Returns the string representation of the char array or null.

Parameters:

value - the character array.

Returns:

a String or null

Since:

3.9

See Also:

String.valueOf(char[])

wrap

public static String wrap(String str,
                          char wrapWith)

Wraps a string with a char.

 StringUtils.wrap(null, *)        = null
 StringUtils.wrap("", *)          = ""
 StringUtils.wrap("ab", '\0')     = "ab"
 StringUtils.wrap("ab", 'x')      = "xabx"
 StringUtils.wrap("ab", '\'')     = "'ab'"
 StringUtils.wrap("\"ab\"", '\"') = "\"\"ab\"\""

Parameters:: str - the string to be wrapped, may be null; wrapWith - the char that will wrap str
Returns:: the wrapped string, or null if str==null
Since:: 3.4

wrap

public static String wrap(String str,
                          String wrapWith)

Wraps a String with another String.

A null input String returns null.

 StringUtils.wrap(null, *)         = null
 StringUtils.wrap("", *)           = ""
 StringUtils.wrap("ab", null)      = "ab"
 StringUtils.wrap("ab", "x")       = "xabx"
 StringUtils.wrap("ab", "\"")      = "\"ab\""
 StringUtils.wrap("\"ab\"", "\"")  = "\"\"ab\"\""
 StringUtils.wrap("ab", "'")       = "'ab'"
 StringUtils.wrap("'abcd'", "'")   = "''abcd''"
 StringUtils.wrap("\"abcd\"", "'") = "'\"abcd\"'"
 StringUtils.wrap("'abcd'", "\"")  = "\"'abcd'\""

Parameters:: str - the String to be wrapper, may be null; wrapWith - the String that will wrap str
Returns:: wrapped String, null if null String input
Since:: 3.4

wrapIfMissing

public static String wrapIfMissing(String str,
                                   char wrapWith)

Wraps a string with a char if that char is missing from the start or end of the given string.

A new String will not be created if str is already wrapped.

 StringUtils.wrapIfMissing(null, *)        = null
 StringUtils.wrapIfMissing("", *)          = ""
 StringUtils.wrapIfMissing("ab", '\0')     = "ab"
 StringUtils.wrapIfMissing("ab", 'x')      = "xabx"
 StringUtils.wrapIfMissing("ab", '\'')     = "'ab'"
 StringUtils.wrapIfMissing("\"ab\"", '\"') = "\"ab\""
 StringUtils.wrapIfMissing("/", '/')  = "/"
 StringUtils.wrapIfMissing("a/b/c", '/')  = "/a/b/c/"
 StringUtils.wrapIfMissing("/a/b/c", '/')  = "/a/b/c/"
 StringUtils.wrapIfMissing("a/b/c/", '/')  = "/a/b/c/"

Parameters:: str - the string to be wrapped, may be null; wrapWith - the char that will wrap str
Returns:: the wrapped string, or null if str==null
Since:: 3.5

wrapIfMissing

public static String wrapIfMissing(String str,
                                   String wrapWith)

Wraps a string with a string if that string is missing from the start or end of the given string.

A new String will not be created if str is already wrapped.

 StringUtils.wrapIfMissing(null, *)         = null
 StringUtils.wrapIfMissing("", *)           = ""
 StringUtils.wrapIfMissing("ab", null)      = "ab"
 StringUtils.wrapIfMissing("ab", "x")       = "xabx"
 StringUtils.wrapIfMissing("ab", "\"")      = "\"ab\""
 StringUtils.wrapIfMissing("\"ab\"", "\"")  = "\"ab\""
 StringUtils.wrapIfMissing("ab", "'")       = "'ab'"
 StringUtils.wrapIfMissing("'abcd'", "'")   = "'abcd'"
 StringUtils.wrapIfMissing("\"abcd\"", "'") = "'\"abcd\"'"
 StringUtils.wrapIfMissing("'abcd'", "\"")  = "\"'abcd'\""
 StringUtils.wrapIfMissing("/", "/")  = "/"
 StringUtils.wrapIfMissing("a/b/c", "/")  = "/a/b/c/"
 StringUtils.wrapIfMissing("/a/b/c", "/")  = "/a/b/c/"
 StringUtils.wrapIfMissing("a/b/c/", "/")  = "/a/b/c/"

Parameters:: str - the string to be wrapped, may be null; wrapWith - the string that will wrap str
Returns:: the wrapped string, or null if str==null
Since:: 3.5

Class StringUtils

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SPACE

EMPTY

LF

CR

INDEX_NOT_FOUND

Constructor Detail

StringUtils

Method Detail

abbreviate

abbreviate

abbreviate

abbreviate

abbreviateMiddle

appendIfMissing

appendIfMissingIgnoreCase

capitalize

center

center

center

chomp

chomp

chop

compare

compare

compareIgnoreCase

compareIgnoreCase

contains

contains

containsAny

containsAny

containsAny

containsAnyIgnoreCase

containsIgnoreCase

containsNone

containsNone

containsOnly

containsOnly

containsWhitespace

countMatches

countMatches

defaultIfBlank

defaultIfEmpty

defaultString

defaultString

deleteWhitespace

difference

endsWith

endsWithAny

endsWithIgnoreCase

equals

equalsAny

equalsAnyIgnoreCase

equalsIgnoreCase

firstNonBlank

firstNonEmpty

getBytes

getBytes

getCommonPrefix

getDigits

getFuzzyDistance

getIfBlank

getIfEmpty

getJaroWinklerDistance

getLevenshteinDistance

getLevenshteinDistance

indexOf

indexOf

indexOf

indexOf

indexOfAny

indexOfAny

indexOfAny

indexOfAnyBut

indexOfAnyBut