gcc/libjava/java/nio/channels/SelectionKey.java

/* SelectionKey.java -- 
   Copyright (C) 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

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General Public License for more details.

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02111-1307 USA.

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making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package java.nio.channels;

/**
 * @author Michael Koch
 * @since 1.4
 */
public abstract class SelectionKey
{
  public static final int OP_ACCEPT  = 16;
  public static final int OP_CONNECT = 8;
  public static final int OP_READ    = 1;
  public static final int OP_WRITE   = 4;
    
  Object attached;
   
  /**
   * Initializes the selection key.
   */
  protected SelectionKey ()
  {
  }

  /**
   * Attaches obj to the key and returns the old attached object.
   */
  public final Object attach (Object obj)
  {
    Object old = attached;
    attached = obj;
    return old;
  }
   
  /**
   * Returns the object attached to the key.
   */
  public final Object attachment ()
  {
    return attached;
  }    

  /**
   * Tests if the channel attached to this key is ready to accept
   * a new socket connection.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   */
  public final boolean isAcceptable ()
  { 
    return (readyOps () & OP_ACCEPT) != 0;
  }

  /**
   * Tests whether this key's channel has either finished,
   * or failed to finish, its socket-connection operation.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   */
  public final boolean isConnectable ()
  {
    return (readyOps () & OP_CONNECT) != 0;  
  }        
  
  /**
   * Tests if the channel attached to the key is readable.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   */
  public final boolean isReadable ()
  {
    return (readyOps () & OP_READ) != 0; 
  }
  
  /**
   * Tests if the channel attached to the key is writable.
   *
   * @exception CancelledKeyException If this key has been cancelled
   */
  public final boolean isWritable ()
  {
    return (readyOps () & OP_WRITE) != 0;
  }

  /**
   * Requests that the registration of this key's channel with
   * its selector be cancelled.
   */
  public abstract void cancel (); 
 
  /**
   * return the channel attached to the key.
   */
  public abstract SelectableChannel channel ();
  
  /**
   * Returns the key's interest set.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   */
  public abstract int interestOps ();
  
  /**
   * Sets this key's interest set to the given value.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   * @exception IllegalArgumentException If a bit in the set does not
   * correspond to an operation that is supported by this key's channel,
   * that is, if set & ~(channel().validOps()) != 0
   */
  public abstract SelectionKey interestOps (int ops);
 
  /**
   * Tells whether or not this key is valid.
   */
  public abstract boolean isValid ();
 
  /**
   * Retrieves this key's ready-operation set.
   * 
   * @exception CancelledKeyException If this key has been cancelled
   */
  public abstract int readyOps ();
  
  /**
   * Returns the selector for which this key was created.
   */
  public abstract Selector selector ();
}