testidentityhashcode.java

来自「疯狂Java讲义_源码(含Java设计模式CHM」· Java 代码 · 共 32 行

/**
 * Description:
 * <br/>Copyright (C), 2005-2008, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class TestIdentityHashCode
{
	public static void main(String[] args) 
	{
		//下面程序中s1和s2是两个不同对象
		String s1 = new String("Hello");
		String s2 = new String("Hello");
		//String重写了hashCode方法——改为根据字符序列计算hashCode值，
		//因为s1和s2的字符序列相同，所以它们的hashCode方法返回值相同
		System.out.println(s1.hashCode() + "----" + s2.hashCode());
		//s1和s2是不同的字符串对象，所以它们的identityHashCode值不同
		System.out.println(System.identityHashCode(s1) + "----" + 
			System.identityHashCode(s2));
		String s3 = "Java";
		String s4 = "Java";
		//s3和s4是相同的字符串对象，所以它们的identityHashCode值相同
		System.out.println(System.identityHashCode(s3) + "----" + 
			System.identityHashCode(s4));
	}
}