001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.primitives; 016 017import static com.google.common.base.Preconditions.checkArgument; 018import static com.google.common.base.Preconditions.checkElementIndex; 019import static com.google.common.base.Preconditions.checkNotNull; 020import static com.google.common.base.Preconditions.checkPositionIndexes; 021 022import com.google.common.annotations.Beta; 023import com.google.common.annotations.GwtCompatible; 024import com.google.common.annotations.GwtIncompatible; 025import com.google.common.base.Converter; 026import java.io.Serializable; 027import java.util.AbstractList; 028import java.util.Arrays; 029import java.util.Collection; 030import java.util.Collections; 031import java.util.Comparator; 032import java.util.List; 033import java.util.RandomAccess; 034import java.util.Spliterator; 035import java.util.Spliterators; 036import javax.annotation.CheckForNull; 037 038/** 039 * Static utility methods pertaining to {@code int} primitives, that are not already found in either 040 * {@link Integer} or {@link Arrays}. 041 * 042 * <p>See the Guava User Guide article on <a 043 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>. 044 * 045 * @author Kevin Bourrillion 046 * @since 1.0 047 */ 048@GwtCompatible(emulated = true) 049@ElementTypesAreNonnullByDefault 050public final class Ints extends IntsMethodsForWeb { 051 private Ints() {} 052 053 /** 054 * The number of bytes required to represent a primitive {@code int} value. 055 * 056 * <p><b>Java 8 users:</b> use {@link Integer#BYTES} instead. 057 */ 058 public static final int BYTES = Integer.SIZE / Byte.SIZE; 059 060 /** 061 * The largest power of two that can be represented as an {@code int}. 062 * 063 * @since 10.0 064 */ 065 public static final int MAX_POWER_OF_TWO = 1 << (Integer.SIZE - 2); 066 067 /** 068 * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Integer) 069 * value).hashCode()}. 070 * 071 * <p><b>Java 8 users:</b> use {@link Integer#hashCode(int)} instead. 072 * 073 * @param value a primitive {@code int} value 074 * @return a hash code for the value 075 */ 076 public static int hashCode(int value) { 077 return value; 078 } 079 080 /** 081 * Returns the {@code int} value that is equal to {@code value}, if possible. 082 * 083 * @param value any value in the range of the {@code int} type 084 * @return the {@code int} value that equals {@code value} 085 * @throws IllegalArgumentException if {@code value} is greater than {@link Integer#MAX_VALUE} or 086 * less than {@link Integer#MIN_VALUE} 087 */ 088 public static int checkedCast(long value) { 089 int result = (int) value; 090 checkArgument(result == value, "Out of range: %s", value); 091 return result; 092 } 093 094 /** 095 * Returns the {@code int} nearest in value to {@code value}. 096 * 097 * @param value any {@code long} value 098 * @return the same value cast to {@code int} if it is in the range of the {@code int} type, 099 * {@link Integer#MAX_VALUE} if it is too large, or {@link Integer#MIN_VALUE} if it is too 100 * small 101 */ 102 public static int saturatedCast(long value) { 103 if (value > Integer.MAX_VALUE) { 104 return Integer.MAX_VALUE; 105 } 106 if (value < Integer.MIN_VALUE) { 107 return Integer.MIN_VALUE; 108 } 109 return (int) value; 110 } 111 112 /** 113 * Compares the two specified {@code int} values. The sign of the value returned is the same as 114 * that of {@code ((Integer) a).compareTo(b)}. 115 * 116 * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the 117 * equivalent {@link Integer#compare} method instead. 118 * 119 * @param a the first {@code int} to compare 120 * @param b the second {@code int} to compare 121 * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is 122 * greater than {@code b}; or zero if they are equal 123 */ 124 public static int compare(int a, int b) { 125 return (a < b) ? -1 : ((a > b) ? 1 : 0); 126 } 127 128 /** 129 * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}. 130 * 131 * @param array an array of {@code int} values, possibly empty 132 * @param target a primitive {@code int} value 133 * @return {@code true} if {@code array[i] == target} for some value of {@code i} 134 */ 135 public static boolean contains(int[] array, int target) { 136 for (int value : array) { 137 if (value == target) { 138 return true; 139 } 140 } 141 return false; 142 } 143 144 /** 145 * Returns the index of the first appearance of the value {@code target} in {@code array}. 146 * 147 * @param array an array of {@code int} values, possibly empty 148 * @param target a primitive {@code int} value 149 * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no 150 * such index exists. 151 */ 152 public static int indexOf(int[] array, int target) { 153 return indexOf(array, target, 0, array.length); 154 } 155 156 // TODO(kevinb): consider making this public 157 private static int indexOf(int[] array, int target, int start, int end) { 158 for (int i = start; i < end; i++) { 159 if (array[i] == target) { 160 return i; 161 } 162 } 163 return -1; 164 } 165 166 /** 167 * Returns the start position of the first occurrence of the specified {@code target} within 168 * {@code array}, or {@code -1} if there is no such occurrence. 169 * 170 * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array, 171 * i, i + target.length)} contains exactly the same elements as {@code target}. 172 * 173 * @param array the array to search for the sequence {@code target} 174 * @param target the array to search for as a sub-sequence of {@code array} 175 */ 176 public static int indexOf(int[] array, int[] target) { 177 checkNotNull(array, "array"); 178 checkNotNull(target, "target"); 179 if (target.length == 0) { 180 return 0; 181 } 182 183 outer: 184 for (int i = 0; i < array.length - target.length + 1; i++) { 185 for (int j = 0; j < target.length; j++) { 186 if (array[i + j] != target[j]) { 187 continue outer; 188 } 189 } 190 return i; 191 } 192 return -1; 193 } 194 195 /** 196 * Returns the index of the last appearance of the value {@code target} in {@code array}. 197 * 198 * @param array an array of {@code int} values, possibly empty 199 * @param target a primitive {@code int} value 200 * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no 201 * such index exists. 202 */ 203 public static int lastIndexOf(int[] array, int target) { 204 return lastIndexOf(array, target, 0, array.length); 205 } 206 207 // TODO(kevinb): consider making this public 208 private static int lastIndexOf(int[] array, int target, int start, int end) { 209 for (int i = end - 1; i >= start; i--) { 210 if (array[i] == target) { 211 return i; 212 } 213 } 214 return -1; 215 } 216 217 /** 218 * Returns the least value present in {@code array}. 219 * 220 * @param array a <i>nonempty</i> array of {@code int} values 221 * @return the value present in {@code array} that is less than or equal to every other value in 222 * the array 223 * @throws IllegalArgumentException if {@code array} is empty 224 */ 225 @GwtIncompatible( 226 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") 227 public static int min(int... array) { 228 checkArgument(array.length > 0); 229 int min = array[0]; 230 for (int i = 1; i < array.length; i++) { 231 if (array[i] < min) { 232 min = array[i]; 233 } 234 } 235 return min; 236 } 237 238 /** 239 * Returns the greatest value present in {@code array}. 240 * 241 * @param array a <i>nonempty</i> array of {@code int} values 242 * @return the value present in {@code array} that is greater than or equal to every other value 243 * in the array 244 * @throws IllegalArgumentException if {@code array} is empty 245 */ 246 @GwtIncompatible( 247 "Available in GWT! Annotation is to avoid conflict with GWT specialization of base class.") 248 public static int max(int... array) { 249 checkArgument(array.length > 0); 250 int max = array[0]; 251 for (int i = 1; i < array.length; i++) { 252 if (array[i] > max) { 253 max = array[i]; 254 } 255 } 256 return max; 257 } 258 259 /** 260 * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}. 261 * 262 * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned 263 * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code 264 * value} is greater than {@code max}, {@code max} is returned. 265 * 266 * @param value the {@code int} value to constrain 267 * @param min the lower bound (inclusive) of the range to constrain {@code value} to 268 * @param max the upper bound (inclusive) of the range to constrain {@code value} to 269 * @throws IllegalArgumentException if {@code min > max} 270 * @since 21.0 271 */ 272 @Beta 273 public static int constrainToRange(int value, int min, int max) { 274 checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max); 275 return Math.min(Math.max(value, min), max); 276 } 277 278 /** 279 * Returns the values from each provided array combined into a single array. For example, {@code 280 * concat(new int[] {a, b}, new int[] {}, new int[] {c}} returns the array {@code {a, b, c}}. 281 * 282 * @param arrays zero or more {@code int} arrays 283 * @return a single array containing all the values from the source arrays, in order 284 */ 285 public static int[] concat(int[]... arrays) { 286 int length = 0; 287 for (int[] array : arrays) { 288 length += array.length; 289 } 290 int[] result = new int[length]; 291 int pos = 0; 292 for (int[] array : arrays) { 293 System.arraycopy(array, 0, result, pos, array.length); 294 pos += array.length; 295 } 296 return result; 297 } 298 299 /** 300 * Returns a big-endian representation of {@code value} in a 4-element byte array; equivalent to 301 * {@code ByteBuffer.allocate(4).putInt(value).array()}. For example, the input value {@code 302 * 0x12131415} would yield the byte array {@code {0x12, 0x13, 0x14, 0x15}}. 303 * 304 * <p>If you need to convert and concatenate several values (possibly even of different types), 305 * use a shared {@link java.nio.ByteBuffer} instance, or use {@link 306 * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer. 307 */ 308 public static byte[] toByteArray(int value) { 309 return new byte[] { 310 (byte) (value >> 24), (byte) (value >> 16), (byte) (value >> 8), (byte) value 311 }; 312 } 313 314 /** 315 * Returns the {@code int} value whose big-endian representation is stored in the first 4 bytes of 316 * {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getInt()}. For example, the input 317 * byte array {@code {0x12, 0x13, 0x14, 0x15, 0x33}} would yield the {@code int} value {@code 318 * 0x12131415}. 319 * 320 * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more 321 * flexibility at little cost in readability. 322 * 323 * @throws IllegalArgumentException if {@code bytes} has fewer than 4 elements 324 */ 325 public static int fromByteArray(byte[] bytes) { 326 checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES); 327 return fromBytes(bytes[0], bytes[1], bytes[2], bytes[3]); 328 } 329 330 /** 331 * Returns the {@code int} value whose byte representation is the given 4 bytes, in big-endian 332 * order; equivalent to {@code Ints.fromByteArray(new byte[] {b1, b2, b3, b4})}. 333 * 334 * @since 7.0 335 */ 336 public static int fromBytes(byte b1, byte b2, byte b3, byte b4) { 337 return b1 << 24 | (b2 & 0xFF) << 16 | (b3 & 0xFF) << 8 | (b4 & 0xFF); 338 } 339 340 private static final class IntConverter extends Converter<String, Integer> 341 implements Serializable { 342 static final IntConverter INSTANCE = new IntConverter(); 343 344 @Override 345 protected Integer doForward(String value) { 346 return Integer.decode(value); 347 } 348 349 @Override 350 protected String doBackward(Integer value) { 351 return value.toString(); 352 } 353 354 @Override 355 public String toString() { 356 return "Ints.stringConverter()"; 357 } 358 359 private Object readResolve() { 360 return INSTANCE; 361 } 362 363 private static final long serialVersionUID = 1; 364 } 365 366 /** 367 * Returns a serializable converter object that converts between strings and integers using {@link 368 * Integer#decode} and {@link Integer#toString()}. The returned converter throws {@link 369 * NumberFormatException} if the input string is invalid. 370 * 371 * <p><b>Warning:</b> please see {@link Integer#decode} to understand exactly how strings are 372 * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the 373 * value {@code 83}. 374 * 375 * @since 16.0 376 */ 377 @Beta 378 public static Converter<String, Integer> stringConverter() { 379 return IntConverter.INSTANCE; 380 } 381 382 /** 383 * Returns an array containing the same values as {@code array}, but guaranteed to be of a 384 * specified minimum length. If {@code array} already has a length of at least {@code minLength}, 385 * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is 386 * returned, containing the values of {@code array}, and zeroes in the remaining places. 387 * 388 * @param array the source array 389 * @param minLength the minimum length the returned array must guarantee 390 * @param padding an extra amount to "grow" the array by if growth is necessary 391 * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative 392 * @return an array containing the values of {@code array}, with guaranteed minimum length {@code 393 * minLength} 394 */ 395 public static int[] ensureCapacity(int[] array, int minLength, int padding) { 396 checkArgument(minLength >= 0, "Invalid minLength: %s", minLength); 397 checkArgument(padding >= 0, "Invalid padding: %s", padding); 398 return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array; 399 } 400 401 /** 402 * Returns a string containing the supplied {@code int} values separated by {@code separator}. For 403 * example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}. 404 * 405 * @param separator the text that should appear between consecutive values in the resulting string 406 * (but not at the start or end) 407 * @param array an array of {@code int} values, possibly empty 408 */ 409 public static String join(String separator, int... array) { 410 checkNotNull(separator); 411 if (array.length == 0) { 412 return ""; 413 } 414 415 // For pre-sizing a builder, just get the right order of magnitude 416 StringBuilder builder = new StringBuilder(array.length * 5); 417 builder.append(array[0]); 418 for (int i = 1; i < array.length; i++) { 419 builder.append(separator).append(array[i]); 420 } 421 return builder.toString(); 422 } 423 424 /** 425 * Returns a comparator that compares two {@code int} arrays <a 426 * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it 427 * compares, using {@link #compare(int, int)}), the first pair of values that follow any common 428 * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For 429 * example, {@code [] < [1] < [1, 2] < [2]}. 430 * 431 * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays 432 * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}. 433 * 434 * @since 2.0 435 */ 436 public static Comparator<int[]> lexicographicalComparator() { 437 return LexicographicalComparator.INSTANCE; 438 } 439 440 private enum LexicographicalComparator implements Comparator<int[]> { 441 INSTANCE; 442 443 @Override 444 public int compare(int[] left, int[] right) { 445 int minLength = Math.min(left.length, right.length); 446 for (int i = 0; i < minLength; i++) { 447 int result = Ints.compare(left[i], right[i]); 448 if (result != 0) { 449 return result; 450 } 451 } 452 return left.length - right.length; 453 } 454 455 @Override 456 public String toString() { 457 return "Ints.lexicographicalComparator()"; 458 } 459 } 460 461 /** 462 * Sorts the elements of {@code array} in descending order. 463 * 464 * @since 23.1 465 */ 466 public static void sortDescending(int[] array) { 467 checkNotNull(array); 468 sortDescending(array, 0, array.length); 469 } 470 471 /** 472 * Sorts the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 473 * exclusive in descending order. 474 * 475 * @since 23.1 476 */ 477 public static void sortDescending(int[] array, int fromIndex, int toIndex) { 478 checkNotNull(array); 479 checkPositionIndexes(fromIndex, toIndex, array.length); 480 Arrays.sort(array, fromIndex, toIndex); 481 reverse(array, fromIndex, toIndex); 482 } 483 484 /** 485 * Reverses the elements of {@code array}. This is equivalent to {@code 486 * Collections.reverse(Ints.asList(array))}, but is likely to be more efficient. 487 * 488 * @since 23.1 489 */ 490 public static void reverse(int[] array) { 491 checkNotNull(array); 492 reverse(array, 0, array.length); 493 } 494 495 /** 496 * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex} 497 * exclusive. This is equivalent to {@code 498 * Collections.reverse(Ints.asList(array).subList(fromIndex, toIndex))}, but is likely to be more 499 * efficient. 500 * 501 * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or 502 * {@code toIndex > fromIndex} 503 * @since 23.1 504 */ 505 public static void reverse(int[] array, int fromIndex, int toIndex) { 506 checkNotNull(array); 507 checkPositionIndexes(fromIndex, toIndex, array.length); 508 for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--) { 509 int tmp = array[i]; 510 array[i] = array[j]; 511 array[j] = tmp; 512 } 513 } 514 515 /** 516 * Returns an array containing each value of {@code collection}, converted to a {@code int} value 517 * in the manner of {@link Number#intValue}. 518 * 519 * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}. 520 * Calling this method is as thread-safe as calling that method. 521 * 522 * @param collection a collection of {@code Number} instances 523 * @return an array containing the same values as {@code collection}, in the same order, converted 524 * to primitives 525 * @throws NullPointerException if {@code collection} or any of its elements is null 526 * @since 1.0 (parameter was {@code Collection<Integer>} before 12.0) 527 */ 528 public static int[] toArray(Collection<? extends Number> collection) { 529 if (collection instanceof IntArrayAsList) { 530 return ((IntArrayAsList) collection).toIntArray(); 531 } 532 533 Object[] boxedArray = collection.toArray(); 534 int len = boxedArray.length; 535 int[] array = new int[len]; 536 for (int i = 0; i < len; i++) { 537 // checkNotNull for GWT (do not optimize) 538 array[i] = ((Number) checkNotNull(boxedArray[i])).intValue(); 539 } 540 return array; 541 } 542 543 /** 544 * Returns a fixed-size list backed by the specified array, similar to {@link 545 * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to 546 * set a value to {@code null} will result in a {@link NullPointerException}. 547 * 548 * <p>The returned list maintains the values, but not the identities, of {@code Integer} objects 549 * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for 550 * the returned list is unspecified. 551 * 552 * <p><b>Note:</b> when possible, you should represent your data as an {@link ImmutableIntArray} 553 * instead, which has an {@link ImmutableIntArray#asList asList} view. 554 * 555 * @param backingArray the array to back the list 556 * @return a list view of the array 557 */ 558 public static List<Integer> asList(int... backingArray) { 559 if (backingArray.length == 0) { 560 return Collections.emptyList(); 561 } 562 return new IntArrayAsList(backingArray); 563 } 564 565 @GwtCompatible 566 private static class IntArrayAsList extends AbstractList<Integer> 567 implements RandomAccess, Serializable { 568 final int[] array; 569 final int start; 570 final int end; 571 572 IntArrayAsList(int[] array) { 573 this(array, 0, array.length); 574 } 575 576 IntArrayAsList(int[] array, int start, int end) { 577 this.array = array; 578 this.start = start; 579 this.end = end; 580 } 581 582 @Override 583 public int size() { 584 return end - start; 585 } 586 587 @Override 588 public boolean isEmpty() { 589 return false; 590 } 591 592 @Override 593 public Integer get(int index) { 594 checkElementIndex(index, size()); 595 return array[start + index]; 596 } 597 598 @Override 599 public Spliterator.OfInt spliterator() { 600 return Spliterators.spliterator(array, start, end, 0); 601 } 602 603 @Override 604 public boolean contains(@CheckForNull Object target) { 605 // Overridden to prevent a ton of boxing 606 return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1; 607 } 608 609 @Override 610 public int indexOf(@CheckForNull Object target) { 611 // Overridden to prevent a ton of boxing 612 if (target instanceof Integer) { 613 int i = Ints.indexOf(array, (Integer) target, start, end); 614 if (i >= 0) { 615 return i - start; 616 } 617 } 618 return -1; 619 } 620 621 @Override 622 public int lastIndexOf(@CheckForNull Object target) { 623 // Overridden to prevent a ton of boxing 624 if (target instanceof Integer) { 625 int i = Ints.lastIndexOf(array, (Integer) target, start, end); 626 if (i >= 0) { 627 return i - start; 628 } 629 } 630 return -1; 631 } 632 633 @Override 634 public Integer set(int index, Integer element) { 635 checkElementIndex(index, size()); 636 int oldValue = array[start + index]; 637 // checkNotNull for GWT (do not optimize) 638 array[start + index] = checkNotNull(element); 639 return oldValue; 640 } 641 642 @Override 643 public List<Integer> subList(int fromIndex, int toIndex) { 644 int size = size(); 645 checkPositionIndexes(fromIndex, toIndex, size); 646 if (fromIndex == toIndex) { 647 return Collections.emptyList(); 648 } 649 return new IntArrayAsList(array, start + fromIndex, start + toIndex); 650 } 651 652 @Override 653 public boolean equals(@CheckForNull Object object) { 654 if (object == this) { 655 return true; 656 } 657 if (object instanceof IntArrayAsList) { 658 IntArrayAsList that = (IntArrayAsList) object; 659 int size = size(); 660 if (that.size() != size) { 661 return false; 662 } 663 for (int i = 0; i < size; i++) { 664 if (array[start + i] != that.array[that.start + i]) { 665 return false; 666 } 667 } 668 return true; 669 } 670 return super.equals(object); 671 } 672 673 @Override 674 public int hashCode() { 675 int result = 1; 676 for (int i = start; i < end; i++) { 677 result = 31 * result + Ints.hashCode(array[i]); 678 } 679 return result; 680 } 681 682 @Override 683 public String toString() { 684 StringBuilder builder = new StringBuilder(size() * 5); 685 builder.append('[').append(array[start]); 686 for (int i = start + 1; i < end; i++) { 687 builder.append(", ").append(array[i]); 688 } 689 return builder.append(']').toString(); 690 } 691 692 int[] toIntArray() { 693 return Arrays.copyOfRange(array, start, end); 694 } 695 696 private static final long serialVersionUID = 0; 697 } 698 699 /** 700 * Parses the specified string as a signed decimal integer value. The ASCII character {@code '-'} 701 * (<code>'\u002D'</code>) is recognized as the minus sign. 702 * 703 * <p>Unlike {@link Integer#parseInt(String)}, this method returns {@code null} instead of 704 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 705 * and returns {@code null} if non-ASCII digits are present in the string. 706 * 707 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 708 * the change to {@link Integer#parseInt(String)} for that version. 709 * 710 * @param string the string representation of an integer value 711 * @return the integer value represented by {@code string}, or {@code null} if {@code string} has 712 * a length of zero or cannot be parsed as an integer value 713 * @throws NullPointerException if {@code string} is {@code null} 714 * @since 11.0 715 */ 716 @Beta 717 @CheckForNull 718 public static Integer tryParse(String string) { 719 return tryParse(string, 10); 720 } 721 722 /** 723 * Parses the specified string as a signed integer value using the specified radix. The ASCII 724 * character {@code '-'} (<code>'\u002D'</code>) is recognized as the minus sign. 725 * 726 * <p>Unlike {@link Integer#parseInt(String, int)}, this method returns {@code null} instead of 727 * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, 728 * and returns {@code null} if non-ASCII digits are present in the string. 729 * 730 * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite 731 * the change to {@link Integer#parseInt(String, int)} for that version. 732 * 733 * @param string the string representation of an integer value 734 * @param radix the radix to use when parsing 735 * @return the integer value represented by {@code string} using {@code radix}, or {@code null} if 736 * {@code string} has a length of zero or cannot be parsed as an integer value 737 * @throws IllegalArgumentException if {@code radix < Character.MIN_RADIX} or {@code radix > 738 * Character.MAX_RADIX} 739 * @throws NullPointerException if {@code string} is {@code null} 740 * @since 19.0 741 */ 742 @Beta 743 @CheckForNull 744 public static Integer tryParse(String string, int radix) { 745 Long result = Longs.tryParse(string, radix); 746 if (result == null || result.longValue() != result.intValue()) { 747 return null; 748 } else { 749 return result.intValue(); 750 } 751 } 752}