覆盖Java中的成员变量(变量隐藏) [英] Overriding member variables in Java ( Variable Hiding)

问题描述

我正在研究JAVA中的重载成员函数，并考虑尝试使用重载成员变量.

I am studying overriding member functions in JAVA and thought about experimenting with overriding member variables.

所以，我定义了类

public class A{
    public int intVal = 1;
    public void identifyClass()
    {
        System.out.println("I am class A");
    }
}

public class B extends A
{
    public int intVal = 2;
    public void identifyClass()
    {
        System.out.println("I am class B");
    }
}

public class mainClass
{
    public static void main(String [] args)
    {
        A a = new A();
        B b = new B();
        A aRef;
        aRef = a;
        System.out.println(aRef.intVal);
        aRef.identifyClass();
        aRef = b;
        System.out.println(aRef.intVal);
        aRef.identifyClass();
    }
}

输出为:

1
I am class A
1
I am class B

我无法理解为什么将aRef设置为b时intVal仍然是A类?

I am not able to understand why when aRef is set to b intVal is still of class A?

推荐答案

在子类中创建相同名称的变量时，这称为隐藏.现在，生成的子类实际上将具有两者属性.您可以使用super.var或((SuperClass)this).var从超类访问一个.变量甚至不必具有相同的类型.它们只是两个共享名称的变量，就像两个重载方法一样.

When you make a variable of the same name in a subclass, that's called hiding. The resulting subclass will now actually have both properties. You can access the one from the superclass with super.var or ((SuperClass)this).var. The variables don't even have to be of the same type; they are just two variables sharing a name, much like two overloaded methods.

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