/* * Copyright (c) 1994, 2005, 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 sun.misc; /** * ConditionLock is a Lock with a built in state variable.  This class * provides the ability to wait for the state variable to be set to a * desired value and then acquire the lock.<p> * * The lockWhen() and unlockWith() methods can be safely intermixed * with the lock() and unlock() methods. However if there is a thread * waiting for the state variable to become a particular value and you * simply call Unlock(), that thread will not be able to acquire the * lock until the state variable equals its desired value. <p> * * @author      Peter King */public finalclass ConditionLock extends Lock {    private int state = 0;     /**     * Creates a ConditionLock.     */    public ConditionLock () {    }     /**     * Creates a ConditionLock in an initialState.     */    public ConditionLock (int initialState) {        state = initialState;    }     /**     * Acquires the lock when the state variable equals the desired state.     *     * @param desiredState the desired state     * @exception  java.lang.InterruptedException if any thread has     *               interrupted this thread.     */    public synchronized void lockWhen(int desiredState)        throws InterruptedException    {        while (state != desiredState) {            wait();        }        lock();    }     /**     * Releases the lock, and sets the state to a new value.     * @param newState the new state     */    public synchronized void unlockWith(int newState) {        state = newState;        unlock();    }}