Selector.java

/* Selector.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)
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General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package java.nio.channels;

import java.io.IOException;
import java.nio.channels.spi.SelectorProvider;
import java.util.Set;


/**
 * @author Michael Koch
 * @since 1.4
 */
public abstract class Selector
{
  /**
   * Initializes the selector.
   */
  protected Selector()
  {
  }
 
  /**
   * Opens a selector.
   * 
   * @exception IOException If an error occurs
   */
  public static Selector open() throws IOException
  {
    return SelectorProvider.provider().openSelector();
  }

  /**
   * Closes the selector.
   * 
   * @exception IOException If an error occurs
   */
  public abstract void close() throws IOException;
  
  /**
   * Tells whether the selector is open or not.
   */
  public abstract boolean isOpen();
  
  /**
   * Returns this selector's key set.
   * 
   * @exception ClosedSelectorException If this selector is closed.
   */
  public abstract Set<SelectionKey> keys();
 
  /**
   * Returns the SelectorProvider that created the selector.
   */
  public abstract SelectorProvider provider();
  
  /**
   * Selects a set of keys whose corresponding channels are ready
   * for I/O operations.
   * 
   * @exception ClosedSelectorException If this selector is closed.
   * @exception IOException If an error occurs
   */
  public abstract int select() throws IOException;
  
  /**
   * Selects a set of keys whose corresponding channels are ready
   * for I/O operations.
   *
   * @param timeout The timeout to use.
   * 
   * @exception ClosedSelectorException If this selector is closed.
   * @exception IllegalArgumentException If the timeout value is negative.
   * @exception IOException If an error occurs
   */
  public abstract int select(long timeout) throws IOException;
  
  /**
   * Returns this selector's selected-key set.
   * 
   * @exception ClosedSelectorException If this selector is closed.
   */
  public abstract Set<SelectionKey> selectedKeys();
  
  /**
   * Selects a set of keys whose corresponding channels are ready
   * for I/O operations.
   * 
   * @exception ClosedSelectorException If this selector is closed.
   * @exception IOException If an error occurs
   */
  public abstract int selectNow() throws IOException;
  
  /**
   * Causes the first selection operation that has not yet returned to
   * return immediately.
   */
  public abstract Selector wakeup();
}