位运算的面试题解析—按位异或运算：一个数异或运算另一个数两次，结果还是这个数。

package Test;

public class Demo {
	public static void main(String [] args) {
		int a = 3;
		int b = 4;
		
		//第一种方法
		a = a + b;//a =3+4=7
		b = a - b;//b =3+4-4=3
		a = a - b;//a =3+4-3=4
		System.out.println("a="+a);
		System.out.println("b="+b);
		
		int s = 3;
		int m = 4;
		
		//第二种方法
		s = s^m;//s = 3^4
		m = s^m;//s =3^4^4=3
		s = s^m;//s = 3^4^3=4
		System.out.println("s="+s);
		System.out.println("m="+m);
	}
}