java.io

Class PipedReader

java.lang.Object

java.io.Reader

java.io.PipedReader

All Implemented Interfaces:

Closeable

public class PipedReader
extends Reader

An input stream that reads characters from a piped writer to which it is connected.

Data is read and written to an internal buffer. It is highly recommended that the PipedReader and connected PipedWriter be part of different threads. If they are not, there is a possibility that the read and write operations could deadlock their thread.

Author:

Aaron M. Renn (arenn@urbanophile.com)

Constructor Summary

Constructors

Constructor and Description
PipedReader() Creates a new PipedReader that is not connected to a PipedWriter.
PipedReader(int pipeSize) Creates a PipedReader so that it is not yet connected and uses the specified pipe size for the pipe's buffer.
PipedReader(PipedWriter source) This constructor creates a new PipedReader and connects it to the passed in PipedWriter.
PipedReader(PipedWriter source, int pipeSize) Creates a PipedReader so that it is connected to the piped writer src and uses the specified pipe size for the pipe's buffer.

Method Summary

Modifier and Type	Method and Description
void	close() This methods closes the stream so that no more data can be read from it.
void	connect(PipedWriter source) This method connects this stream to the passed in PipedWriter.
int	read() This method reads chars from the stream into a caller supplied buffer.
int	read(char[] buf, int offset, int len) This method reads characters from the stream into a caller supplied buffer.
boolean	ready() Determines whether or not this stream is ready to be read.

Methods inherited from class java.io.Reader

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PipedReader

public PipedReader()

Creates a new PipedReader that is not connected to a PipedWriter. It must be connected before chars can be read from this stream.

PipedReader

public PipedReader(int pipeSize)

Creates a PipedReader so that it is not yet connected and uses the specified pipe size for the pipe's buffer. It must be connected to a PipedWriter before being used.

Parameters:

pipeSize - the size of the pipe's buffer.

Throws:

IllegalArgumentException - if pipeSize <= 0.

Since:

1.6

PipedReader

public PipedReader(PipedWriter source)
            throws IOException

This constructor creates a new PipedReader and connects it to the passed in PipedWriter. The stream is then ready for reading.

Parameters:

source - The PipedWriter to connect this stream to

Throws:

IOException - If source is already connected.

PipedReader

public PipedReader(PipedWriter source,
                   int pipeSize)
            throws IOException

Creates a PipedReader so that it is connected to the piped writer src and uses the specified pipe size for the pipe's buffer. Data written to src will then be available as input from this stream.

Parameters:

src - the stream to connect to.

pipeSize - the size of the pipe's buffer.

Throws:

IOException - if an I/O error occurs.

IllegalArgumentException - if pipeSize <= 0.

Since:

1.6

Method Detail

close

public void close()
           throws IOException

This methods closes the stream so that no more data can be read from it.

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException - If an error occurs

connect

public void connect(PipedWriter source)
             throws IOException

This method connects this stream to the passed in PipedWriter. This stream is then ready for reading. If this stream is already connected or has been previously closed, then an exception is thrown

Parameters:

source - The PipedWriter to connect this stream to

Throws:

IOException - If this PipedReader or source has been connected already.

read

public int read()
         throws IOException

This method reads chars from the stream into a caller supplied buffer. It starts storing chars at position offset into the buffer and reads a maximum of len chars. Note that this method can actually read fewer than len chars. The actual number of chars read is returned. A -1 is returned to indicated that no chars can be read because the end of the stream was reached. If the stream is already closed, a -1 will again be returned to indicate the end of the stream.

This method will block if no char is available to be read.

Overrides:

read in class Reader

Returns:

The char read or -1 if end of stream

Throws:

IOException - If an error occurs

read

public int read(char[] buf,
                int offset,
                int len)
         throws IOException

This method reads characters from the stream into a caller supplied buffer. It starts storing chars at position offset into the buffer and reads a maximum of len chars. Note that this method can actually read fewer than len chars. The actual number of chars read is returned. A -1 is returned to indicated that no chars can be read because the end of the stream was reached - ie close() was called on the connected PipedWriter.

This method will block if no chars are available to be read.

Specified by:

read in class Reader

Parameters:

buf - The buffer into which chars will be stored

offset - The index into the buffer at which to start writing.

len - The maximum number of chars to read.

Returns:

The actual number of chars read, or -1 if end of stream.

Throws:

IOException - If close() was called on this Piped Reader.

ready

public boolean ready()
              throws IOException

Description copied from class: Reader

Determines whether or not this stream is ready to be read. If it returns false the stream may block if a read is attempted, but it is not guaranteed to do so.

This method always returns false in this class

Overrides:

ready in class Reader

Returns:

true if the stream is ready to be read, false otherwise.

Throws:

IOException - If an error occurs