数据交换

class demo1 {
	public static void main(String[] args) {
		int a = 10;
		int b = 20;
		System.out.println("交换前：a:"+a+",b:"+b);
		int c = a;
		a = b;
		b = c;
		System.out.println("交换后：a:"+a+",b:"+b);
	}
}

class demo2 {
	public static void main(String[] args) {
		int a = 10;
		int b = 20;
		System.out.println("交换前：a:"+a+",b:"+b);
		a = a ^ b;
		b = a ^ b; // a ^ b ^ b = a
		a = a ^ b; // a ^ b ^ a = b
		System.out.println("交换后：a:"+a+",b:"+b);
	}
}

class demo3 {
	public static void main(String[] args) {
		int a = 10;
		int b = 20;
		System.out.println("交换前：a:"+a+",b:"+b);
        a = a + b; // a=30
		b = a - b; // b=10
		a = a - b; // a=20
		System.out.println("交换后：a:"+a+",b:"+b);
	}
}

class demo3 {
	public static void main(String[] args) {
		int a = 10;
		int b = 20;
		System.out.println("交换前：a:"+a+",b:"+b);
        b = (a+b) - (a=b); // b=30-20=10,a=20
		System.out.println("交换后：a:"+a+",b:"+b);
	}
}