public class

PipedInputStream

extends InputStream
java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.PipedInputStream

Class Overview

Receives information from a communications pipe. When two threads want to pass data back and forth, one creates a piped output stream and the other one creates a piped input stream.

See Also

Summary

Constants
int PIPE_SIZE The size of the default pipe in bytes.
Fields
protected byte[] buffer The circular buffer through which data is passed.
protected int in The index in buffer where the next byte will be written.
protected int out The index in buffer where the next byte will be read.
Public Constructors
PipedInputStream()
Constructs a new unconnected PipedInputStream.
PipedInputStream(PipedOutputStream out)
Constructs a new PipedInputStream connected to the PipedOutputStream out.
Public Methods
synchronized int available()
Returns the number of bytes that are available before this stream will block.
void close()
Closes this stream.
void connect(PipedOutputStream src)
Connects this PipedInputStream to a PipedOutputStream.
synchronized int read(byte[] bytes, int offset, int count)
Reads at most count bytes from this stream and stores them in the byte array bytes starting at offset.
synchronized int read()
Reads a single byte from this stream and returns it as an integer in the range from 0 to 255.
Protected Methods
synchronized void receive(int oneByte)
Receives a byte and stores it in this stream's buffer.
[Expand]
Inherited Methods
From class java.io.InputStream
From class java.lang.Object
From interface java.io.Closeable

Constants

protected static final int PIPE_SIZE

The size of the default pipe in bytes.

Constant Value: 1024 (0x00000400)

Fields

protected byte[] buffer

The circular buffer through which data is passed.

protected int in

The index in buffer where the next byte will be written.

protected int out

The index in buffer where the next byte will be read.

Public Constructors

public PipedInputStream ()

Constructs a new unconnected PipedInputStream. The resulting stream must be connected to a PipedOutputStream before data may be read from it.

public PipedInputStream (PipedOutputStream out)

Constructs a new PipedInputStream connected to the PipedOutputStream out. Any data written to the output stream can be read from the this input stream.

Parameters
out the piped output stream to connect to.
Throws
IOException if this stream or out are already connected.

Public Methods

public synchronized int available ()

Returns the number of bytes that are available before this stream will block. This implementation returns the number of bytes written to this pipe that have not been read yet.

Returns
  • the number of bytes available before blocking.
Throws
IOException if an error occurs in this stream.

public void close ()

Closes this stream. This implementation releases the buffer used for the pipe and notifies all threads waiting to read or write.

Throws
IOException if an error occurs while closing this stream.

public void connect (PipedOutputStream src)

Connects this PipedInputStream to a PipedOutputStream. Any data written to the output stream becomes readable in this input stream.

Parameters
src the source output stream.
Throws
IOException if either stream is already connected.

public synchronized int read (byte[] bytes, int offset, int count)

Reads at most count bytes from this stream and stores them in the byte array bytes starting at offset. Blocks until at least one byte has been read, the end of the stream is detected or an exception is thrown.

Separate threads should be used to read from a PipedInputStream and to write to the connected PipedOutputStream. If the same thread is used, a deadlock may occur.

Parameters
bytes the array in which to store the bytes read.
offset the initial position in bytes to store the bytes read from this stream.
count the maximum number of bytes to store in bytes.
Returns
  • the number of bytes actually read or -1 if the end of the stream has been reached.
Throws
IndexOutOfBoundsException if offset < 0 or count < 0, or if offset + count is greater than the size of bytes.
InterruptedIOException if the thread reading from this stream is interrupted.
IOException if this stream is closed or not connected to an output stream, or if the thread writing to the connected output stream is no longer alive.
NullPointerException if bytes is null.

public synchronized int read ()

Reads a single byte from this stream and returns it as an integer in the range from 0 to 255. Returns -1 if the end of this stream has been reached. If there is no data in the pipe, this method blocks until data is available, the end of the stream is detected or an exception is thrown.

Separate threads should be used to read from a PipedInputStream and to write to the connected PipedOutputStream. If the same thread is used, a deadlock may occur.

Returns
  • the byte read or -1 if the end of the source stream has been reached.
Throws
IOException if this stream is closed or not connected to an output stream, or if the thread writing to the connected output stream is no longer alive.

Protected Methods

protected synchronized void receive (int oneByte)

Receives a byte and stores it in this stream's buffer. This method is called by write(int). The least significant byte of the integer oneByte is stored at index in in the buffer.

This method blocks as long as buffer is full.

Parameters
oneByte the byte to store in this pipe.
Throws
InterruptedIOException if the buffer is full and the thread that has called this method is interrupted.
IOException if this stream is closed or the thread that has last read from this stream is no longer alive.