java.io
Class PipedReader

java.lang.Object
  extended by java.io.Reader
      extended by java.io.PipedReader
All Implemented Interfaces:
Closeable, Readable

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.


Field Summary
 
Fields inherited from class java.io.Reader
lock
 
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()
          Determines whether or not this stream is ready to be read.
 
Methods inherited from class java.io.Reader
mark, markSupported, read, read, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, 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(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.
Method Detail

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

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