/**
 * THINGS/THINGER 2009
 * Copyright Erich P Gatejen (c) 2001 through 2009  ALL RIGHTS RESERVED
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package things.common.tools;

/**
 * This is a stoplight monitor.
 * <p>
 * @author Erich P. Gatejen
 * @version 1.0
 * <p>
 * <i>Version History</i>
 * <pre>EPG - Adapted from another project- 27 JUN 05
 * </pre> 
 */
public class StoplightMonitor extends Object {

	// Instantiate as green.
	private boolean		greenLight = true;
	
	/**
	 *  Approach the stoplight.  If the light is red, the thread will stop.
	 */
	public void stoplight() {

		// Stop if the light is green.
		while (!greenLight) {
			try {
				synchronized (this) {
					this.wait();
				}
			} catch (InterruptedException e) {
				// Don't date
			}
		}
	}

	/**
	 *  Turn on the stoplight green.
	 */
	public synchronized void turnGreen() {
		greenLight = true;
		this.notifyAll();
	}

	/**
	 *  Turn on the stoplight red.
	 */
	public synchronized void turnRed() {
		greenLight = false;
		this.notifyAll();
	}

}
