001/* Selector.java --
002   Copyright (C) 2002 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.nio.channels;
039
040import java.io.IOException;
041import java.nio.channels.spi.SelectorProvider;
042import java.util.Set;
043
044
045/**
046 * @author Michael Koch
047 * @since 1.4
048 */
049public abstract class Selector
050{
051  /**
052   * Initializes the selector.
053   */
054  protected Selector()
055  {
056  }
057
058  /**
059   * Opens a selector.
060   *
061   * @exception IOException If an error occurs
062   */
063  public static Selector open() throws IOException
064  {
065    return SelectorProvider.provider().openSelector();
066  }
067
068  /**
069   * Closes the selector.
070   *
071   * @exception IOException If an error occurs
072   */
073  public abstract void close() throws IOException;
074
075  /**
076   * Tells whether the selector is open or not.
077   */
078  public abstract boolean isOpen();
079
080  /**
081   * Returns this selector's key set.
082   *
083   * @exception ClosedSelectorException If this selector is closed.
084   */
085  public abstract Set<SelectionKey> keys();
086
087  /**
088   * Returns the SelectorProvider that created the selector.
089   */
090  public abstract SelectorProvider provider();
091
092  /**
093   * Selects a set of keys whose corresponding channels are ready
094   * for I/O operations.
095   *
096   * @exception ClosedSelectorException If this selector is closed.
097   * @exception IOException If an error occurs
098   */
099  public abstract int select() throws IOException;
100
101  /**
102   * Selects a set of keys whose corresponding channels are ready
103   * for I/O operations.
104   *
105   * @param timeout The timeout to use.
106   *
107   * @exception ClosedSelectorException If this selector is closed.
108   * @exception IllegalArgumentException If the timeout value is negative.
109   * @exception IOException If an error occurs
110   */
111  public abstract int select(long timeout) throws IOException;
112
113  /**
114   * Returns this selector's selected-key set.
115   *
116   * @exception ClosedSelectorException If this selector is closed.
117   */
118  public abstract Set<SelectionKey> selectedKeys();
119
120  /**
121   * Selects a set of keys whose corresponding channels are ready
122   * for I/O operations.
123   *
124   * @exception ClosedSelectorException If this selector is closed.
125   * @exception IOException If an error occurs
126   */
127  public abstract int selectNow() throws IOException;
128
129  /**
130   * Causes the first selection operation that has not yet returned to
131   * return immediately.
132   */
133  public abstract Selector wakeup();
134}