Module java.base
Package java.io

Class OutputStreamWriter

java.lang.Object
java.io.Writer
java.io.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 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(anOutputStream));

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:

  • Constructor Details

    • OutputStreamWriter

      public OutputStreamWriter(OutputStream out, String charsetName) throws UnsupportedEncodingException
      Creates an OutputStreamWriter that uses the named charset.
      Parameters:
      out - An OutputStream
      charsetName - The name of a supported charset
      Throws:
      UnsupportedEncodingException - If the named encoding is not supported

    • OutputStreamWriter

      public OutputStreamWriter(OutputStream out)
      Creates an OutputStreamWriter that uses the default character encoding, or where out is a PrintStream, the charset used by the print stream.
      Parameters:
      out - An OutputStream
      See Also:

    • 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 Details

    • 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:

    • 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

    • flush

      public void flush() throws IOException
      Flushes the stream.
      Specified by:
      flush in interface Flushable
      Specified by:
      flush in class 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