Java foundation building--Advanced understanding of the static keyword, the difference between instance variables and static variables in memory

java foundation building-advanced understanding of the static keyword, the difference between instance variables and static variables in memory

1. JVM memory structure (5 areas)

• Heap: The instance object created by new is dynamically allocated.
• Method area: static, constant, permanent reference, static modified.
• Java stack, virtual machine stack, basic data types and object references.
• Native method stack: Native method.
• Program Counter: The location of execution.

2. Code examples

public class UserDemo {
    
    
    private String name;
    private String id;
    private static String sex = "男";

    public UserDemo(String name, String id) {
    
    
        this.name = name;
        this.id = id;
    }

    public static void main(String[] args) {
    
    
        System.out.println(UserDemo.sex);
        UserDemo xiaohoong = new UserDemo("xiaohoong", "111");
        System.out.println(xiaohoong.id);
        System.out.println(xiaohoong.name);
        UserDemo xiaoming = new UserDemo("xiaoming", "222");
        System.out.println(xiaoming.id);
        System.out.println(xiaoming.name);
    }
}

Based on this code, analyze the difference between instance variables and static variables in memory.