使用受保护的构造函数对类进行匿名初始化 [英] Anonymous initialization of class with protected constructor

问题描述

假设我们有一堂课:

public class SomeClass {    
    protected SomeClass () { 
    }
}

在位于不同包中的MainClass中，我尝试执行两行:

In MainClass located in different package I tried to execute two lines:

public static void main(String[] args) {
    SomeClass sac1 = new SomeClass(); 
    SomeClass sac2 = new SomeClass() {}; 
}

由于protected构造函数，在两种情况下我都期望程序失败.令我惊讶的是，匿名初始化工作得很好.有人可以解释一下为什么第二种初始化方法还可以吗?

Because of protected constructor, in both cases I was expecting program to fail. To my suprise, anonymous initialization worked fine. Could somebody explain me why second method of initialization is ok?

推荐答案

您的匿名课程

SomeClass sac2 = new SomeClass() {}; 

基本上变成

public class Anonymous extends SomeClass {
    Anonymous () {
        super();
    }
}

构造函数没有访问修饰符，因此您可以在同一包中毫无问题地调用它.您还可以调用super()，因为可以从子类构造函数访问protected父构造函数.

The constructor has no access modifier, so you can invoke it without problem from within the same package. You can also invoke super() because the protected parent constructor is accessible from a subclass constructor.

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