交换两个变量的值

方法一：使用中间变量

temp = m;

m = n;

n = temp;

int m = 12;int n = 5;int temp = m;  //中间变量tempm = n;n = temp;System.out.println("m:" + m + " n:" + n);

方法二：直接在输出的时候交换

int m 12;int n 5;System.outt.println("m:" + n + " n:" + m);

方法三：加减法

m = m + n; //m = 12 + 5;

n = m - n; //n = 17 - 5;

m = m - n; //m = 17- 12；

当m和n较大时，有可能出现精度损失

int m = 12;int n = 5;m = m + n;n = m - n;m = m - n;System.out.println("m:" + m + " n:" + n);

方法四：乘除法

m = m * n; //m = 12 * 4

n = m / n; //n = 48 / 4

m = m / n; //m = 48 / 4

有可能出现精度损失

int m = 12;int n = 4;m = m * n;n = m / n;m = m / n;System.out.println("m:" + m + " n:" + n);

方法五：异或法

m = m ^ n;

n = m ^ n; //(m ^ n) ^ n == m

m = m ^ n; //(m ^ n) ^ m == n

int m = 12;int n = 5;m = m ^ n;n = m ^ n;    //(m ^ n) ^ n == mm = m ^ n;    //(m ^ n) ^ m == nSystem.out.println("m:" + m + " n:" + n);

class TestFor{	public static void main(String[] args) {		int sum = 0;      //所有偶数的和		int count = 0;     //偶数的个数		for(int i = 1; i < 100; i++){			if(i % 2 == 0){				System.out.println(i);				sum = sum + i;				count++;			}		}		System.out.println("100以内所有偶数的和为："+sum);		System.out.println("100以内所有偶数的个数为："+count);	}}