Java基础-包装类Integer

package com.hspedu.wrapper_;

public class Course463 {
    public static void main(String[] args) {

        method();
    }

    public static void method() {
        Integer i = new Integer(1);
        Integer j = new Integer(1);
        System.out.println(i == j); // false

        // 自动装箱Integer.valueOf，
        // 源码如果在缓存数组-128-127则直接返回，超出部分new创建对象
        Integer m = 1;
        Integer n = 1;
        System.out.println(m == n); // true

        Integer x = 128;
        Integer y = 128;
        System.out.println(x == y); // false
    }
}

 

package com.hspedu.wrapper_;

public class Course464 {
    public static void main(String[] args) {
        // 练习

        Integer i1 = new Integer(127);
        Integer i2 = new Integer(127);
        System.out.println(i1 == i2);   // false

        Integer i3 = new Integer(128);
        Integer i4 = new Integer(128);
        System.out.println(i3 == i4);   // false

        Integer i5 = 127;
        Integer i6 = 127;
        System.out.println(i5 == i6);   // true

        Integer i7 = 128;
        Integer i8 = 128;
        System.out.println(i7 == i8);   // false

        Integer i9 = 127;
        Integer i10 = new Integer(127);
        System.out.println(i9 == i10);  // false

        // 只要有基本数据类型 == 比较的是数值是否相等
        Integer i11 = 127;
        int i12 = 127;
        System.out.println(i11 == i12); // true

        Integer i13 = 128;
        int i14 = 128;
        System.out.println(i13 == i14); // true
    }
}