java的Equal

JDK中Equal的源码如下所示：　

 public boolean equals(Object anObject) {
	if (this == anObject) {
	    return true;
	}
	if (anObject instanceof String) {
	    String anotherString = (String)anObject;
	    int n = count;
	    if (n == anotherString.count) {
		char v1[] = value;
		char v2[] = anotherString.value;
		int i = offset;
		int j = anotherString.offset;
		while (n-- != 0) {
		    if (v1[i++] != v2[j++])
			return false;
		}
		return true;
	    }
	}
	return false;
    }

 

通过如下的例子验证：

　　第一次走到this == anObject返回ture，第二次走完全部，第三次走到if (n == anotherString.count)返回false，所以时间为time1 = 63 time2 = 391 time3 = 78

public void StringEqual() {
		String a = "HelloWorld";
		String b = "HelloWorld";
		long start1 = System.currentTimeMillis(); // <+++ Start timing
		for (int i = 0; i < 10000000; i++)
			a.equals(b);
		long stop1 = System.currentTimeMillis(); // <+++ Stop timing
		System.out.println(" time1 = " + (stop1 - start1));//走到this == anObject返回ture

		String c = "HelloWorld";
		String d = "HelloWorlD";
		long start2 = System.currentTimeMillis(); // <+++ Start timing
		for (int i = 0; i < 10000000; i++)
			c.equals(d);
		long stop2 = System.currentTimeMillis(); // <+++ Stop timing
		System.out.println(" time2 = " + (stop2 - start2));//走完全部

		String e = "HelloWorld";
		String f = "HelloWorld1";
		long start3 = System.currentTimeMillis(); // <+++ Start timing
		for (int i = 0; i < 10000000; i++)
			e.equals(f);
		long stop3 = System.currentTimeMillis(); // <+++ Stop timing
		System.out.println(" time3 = " + (stop3 - start3));//走到if (n == anotherString.count)返回false
		/*
		 * System.out.println(); time1 = 63 time2 = 391 time3 = 78
		 */
	}