WritableByteChannel.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
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package java.nio.channels;

import java.io.IOException;
import java.nio.ByteBuffer;


/**
 * A channel that can write bytes.
 *
 * <p> Only one write operation upon a writable channel may be in progress at
 * any given time.  If one thread initiates a write operation upon a channel
 * then any other thread that attempts to initiate another write operation will
 * block until the first operation is complete.  Whether or not other kinds of
 * I/O operations may proceed concurrently with a write operation depends upon
 * the type of the channel. </p>
 *
 *
 * @author Mark Reinhold
 * @author JSR-51 Expert Group
 * @since 1.4
 */

public interface WritableByteChannel
    extends Channel
{

    /**
     * Writes a sequence of bytes to this channel from the given buffer.
     *
     * <p> An attempt is made to write up to <i>r</i> bytes to the channel,
     * where <i>r</i> is the number of bytes remaining in the buffer, that is,
     * {@code src.remaining()}, at the moment this method is invoked.
     *
     * <p> Suppose that a byte sequence of length <i>n</i> is written, where
     * {@code 0}&nbsp;{@code <=}&nbsp;<i>n</i>&nbsp;{@code <=}&nbsp;<i>r</i>.
     * This byte sequence will be transferred from the buffer starting at index
     * <i>p</i>, where <i>p</i> is the buffer's position at the moment this
     * method is invoked; the index of the last byte written will be
     * <i>p</i>&nbsp;{@code +}&nbsp;<i>n</i>&nbsp;{@code -}&nbsp;{@code 1}.
     * Upon return the buffer's position will be equal to
     * <i>p</i>&nbsp;{@code +}&nbsp;<i>n</i>; its limit will not have changed.
     *
     * <p> Unless otherwise specified, a write operation will return only after
     * writing all of the <i>r</i> requested bytes.  Some types of channels,
     * depending upon their state, may write only some of the bytes or possibly
     * none at all.  A socket channel in non-blocking mode, for example, cannot
     * write any more bytes than are free in the socket's output buffer.
     *
     * <p> This method may be invoked at any time.  If another thread has
     * already initiated a write operation upon this channel, however, then an
     * invocation of this method will block until the first operation is
     * complete. </p>
     *
     * @param  src
     *         The buffer from which bytes are to be retrieved
     *
     * @return The number of bytes written, possibly zero
     *
     * @throws  NonWritableChannelException
     *          If this channel was not opened for writing
     *
     * @throws  ClosedChannelException
     *          If this channel is closed
     *
     * @throws  AsynchronousCloseException
     *          If another thread closes this channel
     *          while the write operation is in progress
     *
     * @throws  ClosedByInterruptException
     *          If another thread interrupts the current thread
     *          while the write operation is in progress, thereby
     *          closing the channel and setting the current thread's
     *          interrupt status
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public int write(ByteBuffer src) throws IOException;

}