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## java.io
Class PipedInputStream

    java.lang.Object
      java.io.InputStream
          java.io.PipedInputStream

public class PipedInputStream
extends InputStream

A piped input stream should be connected to a piped output stream; the piped input stream then provides whatever data bytes are written to the piped output stream. Typically, data is read from a `PipedInputStream` object by one thread and data is written to the corresponding `PipedOutputStream` by some other thread. Attempting to use both objects from a single thread is not recommended, as it may deadlock the thread. The piped input stream contains a buffer, decoupling read operations from write operations, within limits.

Since:
  JDK1.0
See Also:
  `PipedOutputStream`

Field Summary
`protected byte[]` | `buffer` The circular buffer into which incoming data is placed.
`protected int` | `in` The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream.
`protected int` | `out` The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.
`protected static int` | `PIPE_SIZE` The size of the pipe's circular input buffer.

Constructor Summary
`PipedInputStream()` Creates a `PipedInputStream` so that it is not yet connected.
`PipedInputStream(PipedOutputStream src)` Creates a `PipedInputStream` so that it is connected to the piped output stream `src`.

Method Summary
`int` | `available()` Returns the number of bytes that can be read from this input stream without blocking.
`void` | `close()` Closes this piped input stream and releases any system resources associated with the stream.
`void` | `connect(PipedOutputStream src)` Causes this piped input stream to be connected to the piped output stream `src`.
`int` | `read()` Reads the next byte of data from this piped input stream.
`int` | `read(byte[] b, int off, int len)` Reads up to `len` bytes of data from this piped input stream into an array of bytes.
`protected void` | `receive(int b)` Receives a byte of data.

Methods inherited from class java.io.InputStream
`mark, markSupported, read, reset, skip`

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

Field Detail

### PIPE_SIZE

    protected static final int PIPE_SIZE

  The size of the pipe's circular input buffer.

  Since:
    JDK1.1
  See Also:
    Constant Field Values

### buffer

    protected byte[] buffer

  The circular buffer into which incoming data is placed.

  Since:
    JDK1.1

### in

    protected int in

  The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream. `in<0` implies the buffer is empty, `in==out` implies the buffer is full

  Since:
    JDK1.1

### out

    protected int out

  The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.

  Since:
    JDK1.1

Constructor Detail

### PipedInputStream

    public PipedInputStream(PipedOutputStream src)
                     throws IOException

  Creates a `PipedInputStream` so that it is connected to the piped output stream `src`. Data bytes written to `src` will then be available as input from this stream.

Parameters:
  `src` - the stream to connect to.
Throws:
  `IOException` - if an I/O error occurs.

### PipedInputStream

    public PipedInputStream()

  Creates a `PipedInputStream` so that it is not yet connected. It must be connected to a `PipedOutputStream` before being used.

See Also:
  `connect(java.io.PipedOutputStream)`, `PipedOutputStream.connect(java.io.PipedInputStream)`

Method Detail

### connect

    public void connect(PipedOutputStream src)
                 throws IOException

  Causes this piped input stream to be connected to the piped output stream `src`. If this object is already connected to some other piped output stream, an `IOException` is thrown.

  If `src` is an unconnected piped output stream and `snk` is an unconnected piped input stream, they may be connected by either the call:

      snk.connect(src)

  or the call:

      src.connect(snk)

  The two calls have the same effect.

  Parameters:
    `src` - The piped output stream to connect to.
  Throws:
    `IOException` - if an I/O error occurs.

### receive

    protected void receive(int b)
                    throws IOException

  Receives a byte of data. This method will block if no input is available.

  Parameters:
    `b` - the byte being received
  Throws:
    `IOException` - If the pipe is broken.
  Since:
    JDK1.1

### read

    public int read()
             throws IOException

  Reads the next byte of data from this piped input stream. The value byte is returned as an `int` in the range `0` to `255`. If no byte is available because the end of the stream has been reached, the value `-1` is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown. If a thread was providing data bytes to the connected piped output stream, but the thread is no longer alive, then an `IOException` is thrown.

  Specified by:
    `read` in class `InputStream`
  Returns:
    the next byte of data, or `-1` if the end of the stream is reached.
  Throws:
    `IOException` - if the pipe is broken.

### read

    public int read(byte[] b,
                    int off,
                    int len)
             throws IOException

  Reads up to `len` bytes of data from this piped input stream into an array of bytes. Less than `len` bytes will be read if the end of the data stream is reached. This method blocks until at least one byte of input is available. If a thread was providing data bytes to the connected piped output stream, but the thread is no longer alive, then an `IOException` is thrown.

  Overrides:
    `read` in class `InputStream`
  Parameters:
    `b` - the buffer into which the data is read.
    `off` - the start offset of the data.
    `len` - the maximum number of bytes read.
  Returns:
    the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached.
  Throws:
    `IOException` - if an I/O error occurs.
  See Also:
    `InputStream.read()`

### available

    public int available()
                  throws IOException

  Returns the number of bytes that can be read from this input stream without blocking. This method overrides the `available` method of the parent class.

  Overrides:
    `available` in class `InputStream`
  Returns:
    the number of bytes that can be read from this input stream without blocking.
  Throws:
    `IOException` - if an I/O error occurs.
  Since:
    JDK1.0.2

### close

    public void close()
               throws IOException

  Closes this piped input stream and releases any system resources associated with the stream.

  Overrides:
    `close` in class `InputStream`
  Throws:
    `IOException` - if an I/O error occurs.

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.