class  Test{
    public static void main(String[] args){
    int m=12;
    int n=5;
    System.out.println("m:"+m+",n:"+n);

   //方法1:   提供臨時變量
      int temp = m;
           m=n;
           n=temp;
     System.out.println("m:"+m+",n:"+n);

   //方法2: 當m和n比較大時,有可能出現精度損失
    m=m+n;
    n=m-n;
    m=m-n;
    System.out.println(
 
"m:"+m+",n:"+n);
       
   //方法3:  抑或位運算符
    m=m^n;
    n=m^n;   //(m^n)^n==m
    m=m^n;  //(m^n)^m==n
}
}

small case change m and n