一个对象的内存图，两个对象使用同一个方法的内存图，两个引用指向同一个对象的内存图

Java对象内存图解析

原创已于 2023-08-04 21:05:07 修改 · 204 阅读

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#java #内存图

于 2023-08-03 22:20:44 首次发布

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博客主要介绍了Java相关的内存图，包括一个对象的内存图、两个对象使用同一个方法的内存图以及两个引用指向同一个对象的内存图，聚焦于Java内存使用情况的可视化展示。

一个对象的内存图

public class Phone {
    String brand; //品牌
    double price; //价格
    String color; //颜色
    public void call(String who) {
        System.out.println("给" + who + "打电话");
    }
    public void sendMessage() {
        System.out.println("群发短信");
    }
}
class Demo01PhoneOne {
    public static void main(String[] args) {
        Phone one = new Phone();
        System.out.println(one.brand); //null
        System.out.println(one.price); //0.0
        System.out.println(one.color); //null
        one.brand = "苹果";
        one.price = 8388.0;
        one.color = "黑色";
        System.out.println(one.brand); //苹果
        System.out.println(one.price); //8388.0
        System.out.println(one.color); //黑色
        one.call("乔布斯");  //给乔布斯打电话
        one.sendMessage();  //群发短信
    }
}
D:\Java\jdk-17\bin\java.exe "-javaagent:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\lib\idea_rt.jar=9084:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\bin" -Dfile.encoding=UTF-8 -classpath F:\IdeaProjects\JavaSenior\out\production\variableandoperator Demo01PhoneOne
null
0.0
null
苹果
8388.0
黑色
给乔布斯打电话
群发短信

Process finished with exit code 0

两个对象使用同一个方法的内存图

public class Phone {
    String brand; //品牌
    double price; //价格
    String color; //颜色

    public void call(String who) {
        System.out.println("给" + who + "打电话");
    }

    public void sendMessage() {
        System.out.println("群发短信");
    }
}

class Demo02PhoneTwo {
    public static void main(String[] args) {
        Phone one = new Phone();
        System.out.println(one.brand); //null
        System.out.println(one.price); //0.0
        System.out.println(one.color); //null
        one.brand = "苹果";
        one.price = 8388.0;
        one.color = "黑色";
        System.out.println(one.brand); //苹果
        System.out.println(one.price); //8388.0
        System.out.println(one.color); //黑色
        one.call("乔布斯");  //给乔布斯打电话
        one.sendMessage();  //群发短信
        System.out.println("==================");

        Phone two = new Phone();
        System.out.println(two.brand); //null
        System.out.println(two.price); //0.0
        System.out.println(two.color); //null
        two.brand = "三星";
        two.price = 5999.0;
        two.color = "蓝色";
        System.out.println(two.brand); //三星
        System.out.println(two.price); //5999.0
        System.out.println(two.color); //蓝色
        two.call("欧巴");  //给欧巴打电话
        two.sendMessage();  //群发短信
    }
}
D:\Java\jdk-17\bin\java.exe "-javaagent:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\lib\idea_rt.jar=10771:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\bin" -Dfile.encoding=UTF-8 -classpath F:\IdeaProjects\JavaSenior\out\production\variableandoperator Demo02PhoneTwo
null
0.0
null
苹果
8388.0
黑色
给乔布斯打电话
群发短信
==================
null
0.0
null
三星
5999.0
蓝色
给欧巴打电话
群发短信

Process finished with exit code 0

两个引用指向同一个对象的内存图

public class Phone {
    String brand; //品牌
    double price; //价格
    String color; //颜色

    public void call(String who) {
        System.out.println("给" + who + "打电话");
    }

    public void sendMessage() {
        System.out.println("群发短信");
    }
}

class Demo03PhoneSame {
    public static void main(String[] args) {
        Phone one = new Phone();
        System.out.println(one.brand); //null
        System.out.println(one.price); //0.0
        System.out.println(one.color); //null
        one.brand = "苹果";
        one.price = 8388.0;
        one.color = "黑色";
        System.out.println(one.brand); //苹果
        System.out.println(one.price); //8388.0
        System.out.println(one.color); //黑色
        one.call("乔布斯");  //给乔布斯打电话
        one.sendMessage();  //群发短信
        System.out.println("==================");

        Phone two = one;
        System.out.println(two.brand); //苹果
        System.out.println(two.price); //8388.0
        System.out.println(two.color); //黑色
        two.brand = "三星";
        two.price = 5999.0;
        two.color = "蓝色";
        System.out.println(two.brand); //三星
        System.out.println(two.price); //5999.0
        System.out.println(two.color); //蓝色
        two.call("欧巴");  //给欧巴打电话
        two.sendMessage();  //群发短信
    }
}
D:\Java\jdk-17\bin\java.exe "-javaagent:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\lib\idea_rt.jar=11799:D:\BaiduNetdiskDownload\IntelliJ IDEA 2022.2.3\bin" -Dfile.encoding=UTF-8 -classpath F:\IdeaProjects\JavaSenior\out\production\variableandoperator Demo03PhoneSame
null
0.0
null
苹果
8388.0
黑色
给乔布斯打电话
群发短信
==================
苹果
8388.0
黑色
三星
5999.0
蓝色
给欧巴打电话
群发短信

Process finished with exit code 0