继承中的静态块vs初始化器块vs构造函数 [英] static block vs initializer block vs constructor in inheritance

问题描述

我找到了这个例子，我想了解它背后的逻辑吗?构造函数，静态块和初始化程序块如何在继承中工作?在每个阶段都被称为?

i find this example and i want to understand the logic behind it ? how constructors and static blocks and initializer blocks works in inheritance ? in which stage each one is called ?

public class Parent {

    static {
        System.out.println("i am Parent 3");
    }

    {
        System.out.println("i am parent 2");
    }

    public Parent() {
        System.out.println("i am parent 1");
    }

}

public class Son extends Parent {

    static {System.out.println("i am son 3");}
    {System.out.println("i am son 2");}

    public Son() {
        System.out.println("i am son 1");
    }

    public static void main(String[] args) {
        new Son();
    }
}

输出为:

i am Parent 3
i am son 3
i am parent 2
i am parent 1
i am son 2
i am son 1

推荐答案

当该类由JVM加载并初始化时，将调用一次静态块.实例构造器是在构造类的实例时执行的，就像构造函数一样.

A static block is called once, when the class is loaded and initialized by the JVM. An instance initializer is executed when an instance of the class is constructed, just like a constructor.

静态和实例初始化程序

Static and Instance initializers are described in the Java Language Specification

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