The PipedWriter.java Java example source code
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package java.io;
/**
* Piped character-output streams.
*
* @author Mark Reinhold
* @since JDK1.1
*/
public class PipedWriter extends Writer {
/* REMIND: identification of the read and write sides needs to be
more sophisticated. Either using thread groups (but what about
pipes within a thread?) or using finalization (but it may be a
long time until the next GC). */
private PipedReader sink;
/* This flag records the open status of this particular writer. It
* is independent of the status flags defined in PipedReader. It is
* used to do a sanity check on connect.
*/
private boolean closed = false;
/**
* Creates a piped writer connected to the specified piped
* reader. Data characters written to this stream will then be
* available as input from <code>snk.
*
* @param snk The piped reader to connect to.
* @exception IOException if an I/O error occurs.
*/
public PipedWriter(PipedReader snk) throws IOException {
connect(snk);
}
/**
* Creates a piped writer that is not yet connected to a
* piped reader. It must be connected to a piped reader,
* either by the receiver or the sender, before being used.
*
* @see java.io.PipedReader#connect(java.io.PipedWriter)
* @see java.io.PipedWriter#connect(java.io.PipedReader)
*/
public PipedWriter() {
}
/**
* Connects this piped writer to a receiver. If this object
* is already connected to some other piped reader, an
* <code>IOException is thrown.
* <p>
* If <code>snk is an unconnected piped reader and
* <code>src is an unconnected piped writer, they may
* be connected by either the call:
* <blockquote> * src.connect(snk)</pre>
* or the call:
* <blockquote> * snk.connect(src)</pre>
* The two calls have the same effect.
*
* @param snk the piped reader to connect to.
* @exception IOException if an I/O error occurs.
*/
public synchronized void connect(PipedReader snk) throws IOException {
if (snk == null) {
throw new NullPointerException();
} else if (sink != null || snk.connected) {
throw new IOException("Already connected");
} else if (snk.closedByReader || closed) {
throw new IOException("Pipe closed");
}
sink = snk;
snk.in = -1;
snk.out = 0;
snk.connected = true;
}
/**
* Writes the specified <code>char to the piped output stream.
* If a thread was reading data characters from the connected piped input
* stream, but the thread is no longer alive, then an
* <code>IOException is thrown.
* <p>
* Implements the <code>write method of Writer.
*
* @param c the <code>char to be written.
* @exception IOException if the pipe is
* <a href=PipedOutputStream.html#BROKEN> broken,
* {@link #connect(java.io.PipedReader) unconnected}, closed
* or an I/O error occurs.
*/
public void write(int c) throws IOException {
if (sink == null) {
throw new IOException("Pipe not connected");
}
sink.receive(c);
}
/**
* Writes <code>len characters from the specified character array
* starting at offset <code>off to this piped output stream.
* This method blocks until all the characters are written to the output
* stream.
* If a thread was reading data characters from the connected piped input
* stream, but the thread is no longer alive, then an
* <code>IOException is thrown.
*
* @param cbuf the data.
* @param off the start offset in the data.
* @param len the number of characters to write.
* @exception IOException if the pipe is
* <a href=PipedOutputStream.html#BROKEN> broken,
* {@link #connect(java.io.PipedReader) unconnected}, closed
* or an I/O error occurs.
*/
public void write(char cbuf[], int off, int len) throws IOException {
if (sink == null) {
throw new IOException("Pipe not connected");
} else if ((off | len | (off + len) | (cbuf.length - (off + len))) < 0) {
throw new IndexOutOfBoundsException();
}
sink.receive(cbuf, off, len);
}
/**
* Flushes this output stream and forces any buffered output characters
* to be written out.
* This will notify any readers that characters are waiting in the pipe.
*
* @exception IOException if the pipe is closed, or an I/O error occurs.
*/
public synchronized void flush() throws IOException {
if (sink != null) {
if (sink.closedByReader || closed) {
throw new IOException("Pipe closed");
}
synchronized (sink) {
sink.notifyAll();
}
}
}
/**
* Closes this piped output stream and releases any system resources
* associated with this stream. This stream may no longer be used for
* writing characters.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
closed = true;
if (sink != null) {
sink.receivedLast();
}
}
}
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