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}