自动装箱时，存在缓存变量

直接看代码就明白了

public class Test 

{ 

    public  static void main(String[] args)

    {  

        //自动装箱的过程中,如果是一个字节大小数字,即-128~127,那么JVM会将其缓存起来

         Integer num1 = 5;

        Integer num2 = 5;

        Integer num3 = 6;

        System.out.println(num1 == num2);  //true

        System.out.println(num1 == num3);  //false

        

        num1 = -128;

        num2 = -128;

        System.out.println(num1 == num2);//true

        

        num1 = 128;

        num2 = 128;

        System.out.println(num1 == num2);//false

        

    } 

}