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