JVM如何加载Java中的父类 [英] How JVM loads parent classes in Java

问题描述

代码:

class A {
    static {
        System.out.println("loading A static 1");
    }
    static {
        System.out.println("loading A static 2 B.c= "+B.c);        
    }
    static {
        System.out.println("loading static 3");
    }
    static int a=10; 
    A(){        
    }
}

class B extends A{
    static {
       System.out.println("loading B A.a= "+A.a);
    }
    static int c = 50;
}
public class Test {
    public static void main(String[] args) {
        new B();
    }
}

输出:

loading A static 1
loading A static 2 B.c= 0
loading static 3
loading B A.a= 10

从这里我们可以说父类在子类之后加载，而子类在父类之后初始化吗?如果是这样，JVM如何加载类层次结构?

From this out put can we say that the parent class loads after the child class but child class initialize after the parent class? If so how JVM loads class hierarchies?

推荐答案

您可以通过执行 java -verbose Test 来检查:

You can check this by executing it with java -verbose Test:

...
[Loaded A from file:/.../src/main/java/]
[Loaded B from file:/.../src/main/java/]
loading A static 1
loading A static 2 B.c= 0
loading static 3
loading B A.a= 10
...

所以不，父类也是先加载的.

So no, the parent class is loaded first too.

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