java 判断两个数是否异号

java 整型int占4个字节32位，两个数异或后移动31位判断结果，如果是1则异号，如果是0则同号

 public class ShowEnviromentViarible {

     public static void main(String[] args) {
         int num1 = 1;
         int num2 = -1;
         System.out.println("num1 = " + num1);
         System.out.println("num2 = " + num2);
         System.out.println((num1 ^ num2) >>> 31);    //无符号移动31位，最左边补0
         num1 = 1;
         num2 = 1;
         System.out.println("num1 = " + num1);
         System.out.println("num2 = " + num2);
         System.out.println((num1 ^ num2) >>> 31);
         num1 = -1;
         num2 = -1;
         System.out.println("num1 = " + num1);
         System.out.println("num2 = " + num2);
         System.out.println((num1 ^ num2) >>> 31);
     }

 }

output:

num1 = 1
num2 = -1
1
num1 = 1
num2 = 1
0
num1 = -1
num2 = -1
0