Java抽象类（这个关键字） [英] Java Abstract Class (this keyword)

问题描述

我想我误解的东西，如果是这样，我需要帮助。

I think I'm misunderstanding something, and if so, I need help..

让我们说我有以下两类：

Let's say I have the following two classes:

public abstract class Abstraction() {
   protected int number = 0;
   public void printNumber() {
       System.out.println(this.number);
       System.out.println(getNumber());
   }
   public int getNumber() {
       return this.number();
   }
}

public class Reality extends Abstraction {
   int number = 1;
   public Reality() {
       this.printNumber();
   }
}

// some other class
new Reality();

我应该输出的是什么？我越来越0,0（这里的code是一个比较复杂一点，但仍是同样的问题）。
我怎样才能得到的输出是1,1？

What should the output be? I'm getting 0, 0 (the code here is a bit more complicated but still the same issue). How can I get the output to be 1,1?

推荐答案

的数量在现实类< STRONG>的不的覆盖在抽象类的<​​code>数量。因此，抽象类仍然认为自己的数量值 0 。

The number in the Reality class doesn't overwrite the number in the Abstraction class. Therefore, the Abstraction class still sees his own number value as 0.

一个解决方案是：

public class Reality extends Abstraction {
   public Reality() {
       number = 1;
       this.printNumber();
   }
}

由于您的数量在抽象是受保护的，你可以在你的现实访问类。

Because your number in Abstraction is protected, you can access it in your Reality class.

另一个例子是一种方法的一个参数：

Another example is a parameter in a method:

private int number;

public void myMethod(int number){
    number = 2;
}

您私人诠释号的字段的不会设置，相反，的参数的数量将被设置为 2 。

Your private int number field won't be set, instead, the parameter number will be set as 2.

最后，在这个和超级关键字词，请参阅类的编辑：

Finally, a word on the this and super keywords, see an edit of your classes:

public abstract class Abstraction() {
   protected int number = 0;
   public void printNumber() {
       System.out.println(this.number);
       System.out.println(getNumber());
   }
   public int getNumber() {
       return this.number();
   }
}

public class Reality extends Abstraction {
   int number = 1;
   public Reality() {
       System.out.println(number); //Will print 1
       System.out.println(this.number); //Will print 1
       System.out.println(super.number); //Will print 0
   }
}

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