Question

我知道super是一个引用变量，用于引用直接父类对象。但是我发现super和this的哈希码都是相同的，这意味着它们引用了子对象。

然后，super如何用来调用父类对象？

示例代码：

class Animal{
    int a;
    Animal(){
        System.out.println("animal constructor ");
    }
}

class Dog extends Animal{
    int b;
    Dog(){
        System.out.println("dog constructyor ");
        System.out.println(this.hashCode()+" "+super.hashCode());
        System.out.println(this.getClass()+" "+super.getClass());
    }
}
public class Super1{
    public static void main(String[] args){

        Dog d=new Dog();
        System.out.println(d);


    }
}

此外，super和this的类都是相同的。

Answer 1

我知道super是一个引用变量，用于引用直接父类对象。

不，不是。它用于引用父类成员。没有“父类对象”这样的东西。

但是我发现super和hash的哈希码都是相同的，这意味着它们引用了子对象。

不，它没有。

由于您没有覆盖其中任何一个类中的hashCode()，因此当您调用它时，无论您使用哪个引用，都会得到相同的结果。

当你致电super.getClass()时，对象的类别并没有神奇地改变。

Answer 2

which means they refer to child object than how "super" is used to invoke parent class object

and

Also classes of both the super and this are same.

I think that you don't get how the inheritancy works.
When you instantiate a subclass, it relies on the super class to create it (super()) but it doesn't create two objects.
Only an instance of the subclass is created.
Whereas the results that you get in your output.

As a side note, if you had overriden hashCode() in the subclass, invoking super.hashCode() and hashCode() could return a distinct result as the first one would invoke the parent method and the second one would invoke the overriden one.

为什么hashCode（）在通过“super”和“this”调用时给出相同的结果？

2 个答案: