java 练习自动拆箱 装箱

        Integer a = 1;

        Integer b = 2;

        Integer c = 3;

        Integer d = 3;

        Integer e = 321;

        Integer f = 321;

        Long g = 3L;

        Long h = 2L;

        Long bad= null;
         //true
        System.out.println(c==d);
        // false
        System.out.println(e==f);
        // true
        System.out.println(c==(a+b));
        //true
        System.out.println(c.equals(a+b));
        // true 计算自动拆箱   有一部分原始类型就会带坏其他对象
        System.out.println(g==(a+b));
        //false
        System.out.println(g.equals(a+b));
        //true
        System.out.println(g.equals(a+h));
        //int  自动转换为 long
        System.out.println(Integer.MAX_VALUE<Long.MAX_VALUE);
        // true   
        System.out.println(g==3);
         //这个会报错
        System.out.println(bad==3);