不借助第三变量实现两数交换

    public void swapOne(){
        int a = 4;
        int b = 5;
        int c = a;
        a = b;
        b = c;
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

    public void swapTwo(){
        int a = 4;
        int b = 5;
        a=a+b;
        b=a-b;
        a=a-b;
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }

    public void swapThree(){
        int a = 4;
        int b = 5;
        a = a ^ b; // 0101 ^ 0100 ===> 0001，此时a的值为1
        b = a ^ b; // 0001 ^ 0100 ===> 0101，此时b的值为5
        a = a ^ b; // 0001 ^ 0101 ===> 0100，此时a的值为4
        System.out.println("a:"+a); //a:5
        System.out.println("b:"+b); //a:4
    }