Java Virtual machine Memory analysis

The memory of a Java Virtual machine can be divided into three regions: stack stack, heap heaps, method area

Stack

• The stack describes the memory model of the method execution, and each method is called to create a stack frame
• The JVM creates a stack for each thread that holds the information for the thread's execution method
• Stacks are thread-private and cannot be shared between threads
• Advanced Post-out
• Stack is automatically assigned by the system, fast! The stack is a contiguous memory space

Heap

• Heaps are used to store created objects and arrays.
• The JVM has only one heap, shared by the thread being used
• Heap is a discontinuous memory space, flexible allocation, slow speed

Method area

• The JVM has only one method area, which is shared by all threads
• The method area is actually a heap, just for storing class, constant-related information
• Used to store content that is always immutable or unique in a program. (class information, static variables, string constants)

Example code:

public class SxtStu {    //属性fields    int  id;    String  sname;    int  age;        Computer  comp;  //计算机        //方法    void  study(){        System.out.println("我在认真学习！！,使用电脑："+comp.brand);    }        void  play(){        System.out.println("我在玩游戏！王者农药！");     }        //构造方法。用于创建这个类的对象。无参的构造方法可以由系统自动创建。    SxtStu(){        System.out.println("调用了无参的构造方法！");    }        //程序执行的入口，必须要有    //javac  Sxtstu.java   ,   java Sxtstu    public static void main(String[] args) {        SxtStu  stu = new SxtStu();   //创建一个对象        stu.id=1001;        stu.sname= "高淇";        stu.age = 18;                Computer  c1 = new Computer();        c1.brand = "联想";                stu.comp = c1;                stu.play();        stu.study();            }}class  Computer {    String  brand;}

Memory Graph:

Java Virtual machine Memory analysis