有损用临时变量，交换两个变量的值

不利用临时变量，交换两个变量的值

public class ChangeValue
{
    
    /** 
     * <不用第三个变量，交换两个变量的值>
     */
    public static void main(String[] args)
    {
        //方法一  精简,一行代码搞定 
        int x = 3, y = 7, t = 123;
        System.out.printf("x = %d, y = %d\n", x, y);
        x = y + 0 * (y = x); 
        System.out.printf("x = %d, y = %d\n", x, y);
        
        //方法二   简单明了 
        int p = 4, q = 9;
        System.out.printf("p = %d, q = %d\n", p, q);
        p = p + q; //7
        q = p - q; // 7-5=2  q == p
        p = p - q; //7-2  
        System.out.printf("p = %d, q = %d\n", p, q);
        
        //方法三  兼容,支持Integer.MAXVALUE的+操作  
        int a = 2, b = 5;
        System.out.printf("a = %d, b = %d\n", a, b);
        a ^= b;
        b ^= a;
        a ^= b;
        System.out.printf("a = %d, b = %d\n", a, b);
        
        //方法四  字符串 数组
        String s1 = "111", s2 = "222";
        System.out.printf("s1 = %s, s2 = %s\n", s1, s2);
        s1 = s1 + "," + s2;
        s2 = s1;
        s1 = s1.split(",")[1];
        s2 = s2.split(",")[0];
        System.out.printf("s1 = %s, s2 = %s\n", s1, s2);
        
        //方法五  字符串 表达式（类似方法一）
        String str1 = "aaa", str2 = "bbb";
        System.out.printf("str1 = %s, str2 = %s\n", str1, str2);
        str1 = str2 + ((str2 = str1) == "" ? "" : "");
        System.out.printf("str1 = %s, str2 = %s\n", str1, str2);
    }
    
}