继承与"this"关键词 [英] Inheritance and the "this" keyword

问题描述

假设我们有下一种情况:

Suppose that we have next situation:

父类A:

class A{  
    public A(){}
    public doSomething(){  
        System.out.println(this.getClass());
    }
}

有B级子班的孩子:

class B extends A{  
    public B(){}
    public void doSomething(){
        super.doSomething();
        System.out.println(this.getClass());
    }
}

和主班:

class Main{  
    public static void main(String[] args){
        A ab=new B();
        ab.doSomething();
    }
}

当我执行此代码时，结果是

When I execute this code result is

B  
B

为什么当 reference 的类型为A时，在超类A中引用的this返回B作为类?

Why does this, referenced in superclass A, returns B as a class when the reference is of type A?

推荐答案

引用无关紧要，它是实例化对象的类.您正在创建的对象的类型为B，因此this.getClass()总是会返回B.

It doesn't matter what the reference is, it's the instantiated object's class that counts. The object that you're creating is of type B, therefore this.getClass() is always going to return B.

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