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   * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
   * 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
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.nio.channels;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  
  
  /**
   * A channel that can read bytes.
   *
   * <p> Only one read operation upon a readable channel may be in progress at
   * any given time.  If one thread initiates a read operation upon a channel
   * then any other thread that attempts to initiate another read operation will
   * block until the first operation is complete.  Whether or not other kinds of
   * I/O operations may proceed concurrently with a read operation depends upon
   * the type of the channel. </p>
   *
   *
   * @author Mark Reinhold
   * @author JSR-51 Expert Group
   * @since 1.4
   */
  
  public interface ReadableByteChannel extends Channel {
  
      /**
       * Reads a sequence of bytes from this channel into the given buffer.
       *
       * <p> An attempt is made to read up to <i>r</i> bytes from the channel,
       * where <i>r</i> is the number of bytes remaining in the buffer, that is,
       * <tt>dst.remaining()</tt>, at the moment this method is invoked.
       *
       * <p> Suppose that a byte sequence of length <i>n</i> is read, where
       * <tt>0</tt>&nbsp;<tt>&lt;=</tt>&nbsp;<i>n</i>&nbsp;<tt>&lt;=</tt>&nbsp;<i>r</i>.
       * This byte sequence will be transferred into the buffer so that the first
       * byte in the sequence is at index <i>p</i> and the last byte is at index
       * <i>p</i>&nbsp;<tt>+</tt>&nbsp;<i>n</i>&nbsp;<tt>-</tt>&nbsp;<tt>1</tt>,
       * where <i>p</i> is the buffer's position at the moment this method is
       * invoked.  Upon return the buffer's position will be equal to
       * <i>p</i>&nbsp;<tt>+</tt>&nbsp;<i>n</i>; its limit will not have changed.
       *
       * <p> A read operation might not fill the buffer, and in fact it might not
       * read any bytes at all.  Whether or not it does so depends upon the
       * nature and state of the channel.  A socket channel in non-blocking mode,
       * for example, cannot read any more bytes than are immediately available
       * from the socket's input buffer; similarly, a file channel cannot read
       * any more bytes than remain in the file.  It is guaranteed, however, that
       * if a channel is in blocking mode and there is at least one byte
       * remaining in the buffer then this method will block until at least one
       * byte is read.
       *
       * <p> This method may be invoked at any time.  If another thread has
       * already initiated a read operation upon this channel, however, then an
       * invocation of this method will block until the first operation is
       * complete. </p>
       *
       * @param  dst
       *         The buffer into which bytes are to be transferred
       *
       * @return  The number of bytes read, possibly zero, or <tt>-1</tt> if the
       *          channel has reached end-of-stream
       *
       * @throws  NonReadableChannelException
       *          If this channel was not opened for reading
       *
       * @throws  ClosedChannelException
       *          If this channel is closed
       *
       * @throws  AsynchronousCloseException
       *          If another thread closes this channel
       *          while the read operation is in progress
       *
       * @throws  ClosedByInterruptException
       *          If another thread interrupts the current thread
       *          while the read 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 read(ByteBuffer dst) throws IOException;
  
  }
  