2 基础类型比较

        Integer i1 = 40;
        Integer i2 = 40;
        Integer i3 = 0;
        Integer i4 = new Integer(40);
        Integer i5 = new Integer(40);
        Integer i6 = new Integer(0);
        System.out.println("i1=i2   " + (i1 == i2)); //true
        System.out.println("i1=i2+i3   " + (i1 == i2 + i3));//  true
        System.out.println("i1=i4   " + (i1 == i4)); //false
        System.out.println("i4=i5   " + (i4 == i5));//false
        System.out.println("i4=i5+i6   " + (i4 == i5 + i6));//true
        System.out.println("40=i5+i6   " + (40 == i5 + i6)); //true

1 System.out.println(“i1=i2 “ + (i1 == i2)); //true

原因i1和i2 在 -128 到127 之间，同一个cahe

2 System.out.println(“i1=i2+i3 “ + (i1 == i2 + i3));// true

因为i2+i3计算之后直接退化为int

3 System.out.println(“i1=i4 “ + (i1 == i4)); //false

i1 是cahe中的 i4是新new出来的

4 System.out.println(“i4=i5 “ + (i4 == i5));//false

i4 i5 都是new出来的不一样

5 System.out.println(“i4=i5+i6 “ + (i4 == i5 + i6));//true

遇到运算直接拆包，i4==40 当然是true

6 System.out.println(“40=i5+i6 “ + (40 == i5 + i6)); //true

遇到运算直接拆包，40==40 当然是true