java.io
Class PipedReader

java.lang.Object
  java.io.Reader
      java.io.PipedReader

public class PipedReader

extends Reader

Piped character-input streams.

Since:

JDK1.1

Author:

Mark Reinhold

Field Summary

(package private) char[]	buffer The circular buffer into which incoming data is placed.
(package private) boolean	closedByReader
(package private) boolean	closedByWriter
(package private) boolean	connected
(package private) int	in The index of the position in the circular buffer at which the next character of data will be stored when received from the connected piped writer.
(package private) int	out The index of the position in the circular buffer at which the next character of data will be read by this piped reader.
(package private) static int	PIPE_SIZE The size of the pipe's circular input buffer.
(package private) Thread	readSide
(package private) Thread	writeSide

Fields inherited from class java.io.Reader

lock

Constructor Summary

PipedReader()
Creates a PipedReader so that it is not yet connected.

PipedReader(PipedWriter src)
Creates a PipedReader so that it is connected to the piped writer src.

Method Summary

void	close() Closes this piped stream and releases any system resources associated with the stream.
void	connect(PipedWriter src) Causes this piped reader to be connected to the piped writer src.
int	read() Reads the next character of data from this piped stream.
int	read(char[] cbuf, int off, int len) Reads up to len characters of data from this piped stream into an array of characters.
boolean	ready() Tell whether this stream is ready to be read.
(package private) void	receive(char[] c, int off, int len) Receives data into an array of characters.
(package private) void	receive(int c) Receives a char of data.
(package private) void	receivedLast() Notifies all waiting threads that the last character of data has been received.

Methods inherited from class java.io.Reader

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

closedByWriter

boolean closedByWriter

closedByReader

boolean closedByReader

connected

boolean connected

readSide

Thread readSide

writeSide

Thread writeSide

PIPE_SIZE

static final int PIPE_SIZE

The size of the pipe's circular input buffer.

See Also:

Constant Field Values

buffer

char[] buffer

The circular buffer into which incoming data is placed.

in

int in

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

out

int out

The index of the position in the circular buffer at which the next character of data will be read by this piped reader.

Constructor Detail

PipedReader

public PipedReader(PipedWriter src)
            throws IOException

Creates a PipedReader so that it is connected to the piped writer src. Data 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.

PipedReader

public PipedReader()

Creates a PipedReader so that it is not yet connected. It must be connected to a PipedWriter before being used.

See Also:

connect(java.io.PipedWriter), PipedWriter.connect(java.io.PipedReader)

Method Detail

connect

public void connect(PipedWriter src)
             throws IOException

Causes this piped reader to be connected to the piped writer src. If this object is already connected to some other piped writer, an IOException is thrown.

If src is an unconnected piped writer and snk is an unconnected piped reader, 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 writer to connect to.

Throws:

IOException - if an I/O error occurs.

receive

void receive(int c)
       throws IOException

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

Throws:

IOException

receive

void receive(char[] c,
             int off,
             int len)
       throws IOException

Receives data into an array of characters. This method will block until some input is available.

Throws:

IOException

receivedLast

void receivedLast()

Notifies all waiting threads that the last character of data has been received.

read

public int read()
         throws IOException

Reads the next character of data from this piped stream. If no character 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 characters to the connected piped writer, but the thread is no longer alive, then an IOException is thrown.

Overrides:

read in class Reader

Returns:

the next character of data, or -1 if the end of the stream is reached.

Throws:

IOException - if the pipe is broken.

read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException

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

Specified by:

read in class Reader

Parameters:

cbuf - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of characters read.

Returns:

the total number of characters 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.

ready

public boolean ready()
              throws IOException

Tell whether this stream is ready to be read. A piped character stream is ready if the circular buffer is not empty.

Overrides:

ready in class Reader

Returns:

True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

Throws:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

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

Specified by:

close in class Reader

Throws:

IOException - if an I/O error occurs.