java.io

Class PipedReader

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.

UNKNOWN: The JDK implementation appears to have some undocumented functionality where it keeps track of what thread is writing to pipe and throws an IOException if that thread susequently dies. This behaviour seems dubious and unreliable - we don't implement it.

Constructor Summary
	PipedReader() Creates a new `PipedReader` that is not connected to a `PipedWriter`.
	PipedReader(PipedWriter source) This constructor creates a new `PipedReader` and connects it to the passed in `PipedWriter`.

Method Summary
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()

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(PipedWriter source)

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.

Method Detail

close

public void close()

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

Throws: IOException If an error occurs

connect

public void connect(PipedWriter source)

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()

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.

read

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

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.

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.

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

ready

public boolean ready()