PipedWriter (Java SE 25 & JDK 25)
Description: declaration: module: java.base, package: java.io, class: PipedWriter
Keywords: java.io.PipedWriter class

# Class PipedWriter

java.lang.Object
java.io.Writer
java.io.PipedWriter

All Implemented Interfaces:
  `Closeable, Flushable, Appendable, AutoCloseable`

public class PipedWriter extends Writer
Piped character-output streams.

Since:
  1.1

- ## Field Summary

  ### Fields declared in class Writer

  `lock`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `PipedWriter()`
  Creates a piped writer that is not yet connected to a piped reader.
  `PipedWriter(PipedReader snk)`
  Creates a piped writer connected to the specified piped reader.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `close()`
  Closes this piped output stream and releases any system resources associated with this stream.
  `void`
  `connect(PipedReader snk)`
  Connects this piped writer to a receiver.
  `void`
  `flush()`
  Flushes this output stream and forces any buffered output characters to be written out.
  `void`
  `write(char[] cbuf, int off, int len)`
  Writes `len` characters from the specified character array starting at offset `off` to this piped output stream.
  `void`
  `write(int c)`
  Writes the specified `char` to the piped output stream.

  ### Methods declared in class Writer

  `append, append, append, nullWriter, write, write, write`

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### PipedWriter

    public PipedWriter(PipedReader snk) throws IOException
    Creates a piped writer connected to the specified piped reader. Data characters written to this stream will then be available as input from `snk`.
    Parameters:
      `snk` - The piped reader to connect to.
    Throws:
      `IOException` - if an I/O error occurs.

  - ### PipedWriter

    public PipedWriter()
    Creates a piped writer that is not yet connected to a piped reader. It must be connected to a piped reader, either by the receiver or the sender, before being used.
    See Also:
      - `PipedReader.connect(java.io.PipedWriter)`
      - `connect(java.io.PipedReader)`

- ## Method Details

  - ### connect

    public void connect(PipedReader snk) throws IOException
    Connects this piped writer to a receiver. If this object is already connected to some other piped reader, an `IOException` is thrown.

    If `snk` is an unconnected piped reader and `src` is an unconnected piped writer, they may be connected by either the call:

            src.connect(snk)

    or the call:

            snk.connect(src)

    The two calls have the same effect.
    Parameters:
      `snk` - the piped reader to connect to.
    Throws:
      `IOException` - if an I/O error occurs.

  - ### write

    public void write(int c) throws IOException
    Writes the specified `char` to the piped output stream. If a thread was reading data characters from the connected piped input stream, but the thread is no longer alive, then an `IOException` is thrown.

    Implements the `write` method of `Writer`.

    Overrides:
      `write` in class `Writer`
    Parameters:
      `c` - the `char` to be written.
    Throws:
      `IOException` - if the pipe is `broken`, `unconnected`, closed or an I/O error occurs.

  - ### write

    public void write(char[] cbuf, int off, int len) throws IOException
    Writes `len` characters from the specified character array starting at offset `off` to this piped output stream. This method blocks until all the characters are written to the output stream. If a thread was reading data characters from the connected piped input stream, but the thread is no longer alive, then an `IOException` is thrown.
    Specified by:
      `write` in class `Writer`
    Parameters:
      `cbuf` - the data.
      `off` - the start offset in the data.
      `len` - the 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 the pipe is `broken`, `unconnected`, closed or an I/O error occurs.

  - ### flush

    public void flush() throws IOException
    Flushes this output stream and forces any buffered output characters to be written out. This will notify any readers that characters are waiting in the pipe.
    Specified by:
      `flush` in interface `Flushable`
    Specified by:
      `flush` in class `Writer`
    Throws:
      `IOException` - if the pipe is closed, or an I/O error occurs.

  - ### close

    public void close() throws IOException
    Closes this piped output stream and releases any system resources associated with this stream. This stream may no longer be used for writing characters.
    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.