Java class load order and sequence of example (Demo program)

A, main function object instance

father

package com.learn;

public class Father {

    //静态变量
    public static int num_1 = 1;

    //静态代码块
    static {
        //判断静态变量和静态代码块的执行顺序
        System.out.println("Father类的静态变量" + num_1);
        System.out.println("Father类的静态代码块");
    }

    //普通变量
    public int num_2 = 2;

    //匿名代码块
    {
        System.out.println("Father类的普通变量=" + num_2);
        System.out.println("Father类的匿名代码块");
    }

    //构造函数
    public Father() {
        System.out.println("Father类的构造函数");
    }

}

Subclass

package com.learn;

public class Son extends Father{

    //静态变量
    public static int num_3 = 3;

    //静态代码块
    static {
        //判断静态变量和静态代码块的执行顺序
        System.out.println("Son类的静态变量" + num_3);
        System.out.println("Son类的静态代码块");
    }

    //普通变量
    public int num_4 = 4;

    //匿名代码块
    {
        System.out.println("Son类的普通变量=" + num_4);
        System.out.println("Son类的匿名代码块");
    }

    //构造函数
    public Son() {
        System.out.println("Son类的构造函数");
    }

    //主函数
    public static void main(String[] args) {
        Son Son = new Son();
    }
}

operation result

Father类的静态变量1
Father类的静态代码块
Son类的静态变量3
Son类的静态代码块
Father类的普通变量=2
Father类的匿名代码块
Father类的构造函数
Son类的普通变量=4
Son类的匿名代码块
Son类的构造函数

Two, main function does not instantiate objects

//主函数
    public static void main(String[] args) {
        //Son Son = new Son();
    }

operation result

Father类的静态变量1
Father类的静态代码块
Son类的静态变量3
Son类的静态代码块

CONCLUSIONS

Class loading: parent class static variable> parent class static block of code> subclass static variable> greater than the subclass static block of code
class instantiation: parent class non-static variable> parent class anonymous block> parent class constructor> subclasses non-static variable> subclass block non-static> subclass constructor