idgenerator.java

发布/订阅系统路由重配算法,可应用于ad hoc环境

/*
 * project: RebecaSim
 * package: util
 * file:    IDGenerator.java
 * version: 0.1
 * date:    31.03.2005
 * 
 * This software is part of the diploma thesis "Ein adaptives Brokernetz 
 * für Publish/Subscribe Systeme".
 */
package util;

/**
 * An <code>IDGenerator</code> provides <code>long</code> values 
 * convenient to build (unique) identifiers on.
 * As long as the value range is not exhausted all returned values are unique.
 * A new id-value is obtained by incrementing the last returned one.
 * @version 0.1 31.03.2005
 * @author  Helge Parzyjegla
 */
public class IDGenerator {
	
	/** All new ID values are created incrementally based on this counter. */
	private static long id;
	
	/**
	 * Creates a new <code>IDGenerator</code> instance with the first 
	 * (returned) id-value initialized to <code>0</code>. 
	 */
	public IDGenerator() {
		id = 0;
	}
	
	/**
	 * Creates a new <code>IDGenerator</code> instance with the first 
	 * (returned) id-value initialized to <code>value</code>.
	 * @param value value of the first returned id 
	 */
	public IDGenerator(long value) {
		id = value;
	}
	
	/**
	 * Returns the next id-value, needed by the <code>ID</code> class to 
	 * create a new <code>ID</code> object.
	 * @return the next id-value
	 */
	public synchronized long getId(){
		return id++;
	}
	
	/**
	 * Resets the <code>IDGenerator</code> instance to <code>0</code>.
	 */
	public synchronized void reset() {
		id = 0;
	}
	
	/**
	 * Resets the <code>IDGenerator</code> instance to <code>value</code>.
	 * @param value value of the next id after reset
	 */
	public synchronized void reset(long value) {
		id = value;
	}
}