Java中int和Integer值之间相互比较

本文为joshua317原创文章,转载请注明：转载自joshua317博客 https://www.joshua317.com/article/201

请同时参考文章https://www.joshua317.com/article/200

package com.joshua317;

public class Main {

    public static void main(String[] args) {
        Integer i1 = new Integer(127);
        Integer i2 = new Integer(127);
        //两个引用对象，永远是不相等的，因为new生成的是两个对象，其内存地址不同
        System.out.println("i1==i2:" + (i1 == i2));//false

        Integer i3 = new Integer(128);
        Integer i4 = new Integer(128);
        //两个引用对象，永远是不相等的，因为new生成的是两个对象，其内存地址不同
        System.out.println("i3==i4:" + (i3 == i4));//false

        Integer i5 = 127;//自动装箱，底层是Integer.valueOf()
        Integer i6 = 127;//自动装箱，底层是Integer.valueOf()
        //-128~127走值缓存，同一个对象引用
        System.out.println("i5==i6:" + (i5 == i6));//true

        Integer i7 = 128;//自动装箱，底层是Integer.valueOf()
        Integer i8 = 128;//自动装箱，底层是Integer.valueOf()
        //-128~127走值缓存，超出范围,产生不同对象
        System.out.println("i7==i8:" + (i7 == i8));//false

        Integer i9 = 127;//自动装箱，底层是Integer.valueOf()
        Integer i10 = new Integer(127);
        //不同对象引用
        System.out.println("i9==i10:" + (i9 == i10));//false

        Integer i11 = 128;//自动装箱，底层是Integer.valueOf()
        Integer i12 = new Integer(128);
        //不同对象引用
        System.out.println("i11==i12:" + (i11 == i12));//false

        Integer i13 = 127;//自动装箱，底层是Integer.valueOf()
        Integer i14 = Integer.valueOf(127);
        //-128~127走值缓存，同一个对象引用
        System.out.println("i13==i14:" + (i13 == i14));//true

        Integer i15 = 128;
        Integer i16 = Integer.valueOf(128);
        //-128~127走值缓存，超出范围,产生不同对象
        System.out.println("i15==i16:" + (i15 == i16));//false

        Integer i17 = Integer.valueOf(127);
        Integer i18 = Integer.valueOf(127);
        //-128~127走值缓存，同一个对象引用
        System.out.println("i17==i18:" + (i17 == i18));//true

        Integer i19 = Integer.valueOf(128);
        Integer i20 = Integer.valueOf(128);
        //-128~127走值缓存，超出范围,产生不同对象
        System.out.println("i19==i20:" + (i19 == i20));//false

        System.out.println("============华丽分割线============");

        /**
         * Integer变量和int变量比较时，只要两个变量的值是向等的，则结果为true
         * 因为包装类Integer和基本数据类型int比较时，Java会自动拆包装为int，
         * 然后进行比较，实际上就变为两个int变量的比较
         */

        Integer i21 = 127;
        int i22 = 127;
        System.out.println("i21==i22:" + (i21 == i22));//true

        Integer i23 = 128;
        int i24 = 128;
        System.out.println("i23==i24:" + (i23 == i24));//true

        Integer i25 = new Integer(127);
        int i26 = 127;
        System.out.println("i25==i26:" + (i25 == i26));//true

        Integer i27 = new Integer(128);
        int i28 = 128;
        System.out.println("i27==i28:" + (i27 == i28));//true

        Integer i29 = Integer.valueOf(127);
        int i30 = 127;
        System.out.println("i29==i30:" + (i29 == i30));//true

        Integer i31 = Integer.valueOf(128);
        int i32 = 128;
        System.out.println("i31==i32:" + (i31 == i32));//true
    }
}

 

 

本文为joshua317原创文章,转载请注明：转载自joshua317博客 https://www.joshua317.com/article/201