Module java.base
Package java.io

Class OutputStreamWriter

  • All Implemented Interfaces:
    Closeable, Flushable, Appendable, AutoCloseable
    Direct Known Subclasses:
    FileWriter

    public class OutputStreamWriter
extends Writer
    An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted.

    Each invocation of a write() method causes the encoding converter to be invoked on the given character(s). The resulting bytes are accumulated in a buffer before being written to the underlying output stream. Note that the characters passed to the write() methods are not buffered.

    For top efficiency, consider wrapping an OutputStreamWriter within a BufferedWriter so as to avoid frequent converter invocations. For example: 

     Writer out
   = new BufferedWriter(new OutputStreamWriter(System.out));

    A surrogate pair is a character represented by a sequence of two char values: A high surrogate in the range '\uD800' to '\uDBFF' followed by a low surrogate in the range '\uDC00' to '\uDFFF'.

    A malformed surrogate element is a high surrogate that is not followed by a low surrogate or a low surrogate that is not preceded by a high surrogate.

    This class always replaces malformed surrogate elements and unmappable character sequences with the charset's default substitution sequence. The CharsetEncoder class should be used when more control over the encoding process is required.

    Since:
    1.1
    See Also:
    BufferedWriter, OutputStream, Charset

    • Constructor Detail

      • OutputStreamWriter

        public OutputStreamWriter​(OutputStream out)
        Creates an OutputStreamWriter that uses the default character encoding.
        Parameters:
        out - An OutputStream

      • OutputStreamWriter

        public OutputStreamWriter​(OutputStream out,
                          Charset cs)
        Creates an OutputStreamWriter that uses the given charset.
        Parameters:
        out - An OutputStream
        cs - A charset
        Since:
        1.4

      • OutputStreamWriter

        public OutputStreamWriter​(OutputStream out,
                          CharsetEncoder enc)
        Creates an OutputStreamWriter that uses the given charset encoder.
        Parameters:
        out - An OutputStream
        enc - A charset encoder
        Since:
        1.4

    • Method Detail

      • getEncoding

        public String getEncoding​()
        Returns the name of the character encoding being used by this stream.

        If the encoding has an historical name then that name is returned; otherwise the encoding's canonical name is returned.

        If this instance was created with the OutputStreamWriter(OutputStream, String) constructor then the returned name, being unique for the encoding, may differ from the name passed to the constructor. This method may return null if the stream has been closed.

        Returns:
        The historical name of this encoding, or possibly null if the stream has been closed
        See Also:
        Charset

      • write

        public void write​(int c)
           throws IOException
        Writes a single character.
        Overrides:
        write in class Writer
        Parameters:
        c - int specifying a character to be written
        Throws:
        IOException - If an I/O error occurs

      • write

        public void write​(char[] cbuf,
                  int off,
                  int len)
           throws IOException
        Writes a portion of an array of characters.
        Specified by:
        write in class Writer
        Parameters:
        cbuf - Buffer of characters
        off - Offset from which to start writing characters
        len - Number of characters to write
        Throws:
        IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given array
        IOException - If an I/O error occurs

      • write

        public void write​(String str,
                  int off,
                  int len)
           throws IOException
        Writes a portion of a string.
        Overrides:
        write in class Writer
        Parameters:
        str - A String
        off - Offset from which to start writing characters
        len - Number of characters to write
        Throws:
        IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given string
        IOException - If an I/O error occurs

      • append

        public Writer append​(CharSequence csq,
                     int start,
                     int end)
              throws IOException
        Description copied from class: Writer
        Appends a subsequence of the specified character sequence to this writer. Appendable.

        An invocation of this method of the form out.append(csq, start, end) when csq is not null behaves in exactly the same way as the invocation 

        
     out.write(csq.subSequence(start, end).toString())
        Specified by:
        append in interface Appendable
        Overrides:
        append in class Writer
        Parameters:
        csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
        start - The index of the first character in the subsequence
        end - The index of the character following the last character in the subsequence
        Returns:
        This writer
        Throws:
        IOException - If an I/O error occurs

      • append

        public Writer append​(CharSequence csq)
              throws IOException
        Description copied from class: Writer
        Appends the specified character sequence to this writer.

        An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation 

             out.write(csq.toString())

        Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

        Specified by:
        append in interface Appendable
        Overrides:
        append in class Writer
        Parameters:
        csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.
        Returns:
        This writer
        Throws:
        IOException - If an I/O error occurs

      • close

        public void close​()
           throws IOException
        Description copied from class: Writer
        Closes the stream, flushing it first. Once the stream has been closed, further write() or flush() invocations will cause an IOException to be thrown. Closing a previously closed stream has no effect.
        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Closeable
        Specified by:
        close in class Writer
        Throws:
        IOException - If an I/O error occurs