java强制扩展类 [英] java force an extending class

问题描述

在Java中，我可以不知何故强迫一个扩展抽象类的类来实现它的构造函数，一个Object作为参数？

In Java, can I somehow force a class that extends an abstract class to implement its constructor with a Object as a parameter?

像

public abstract class Points {

    //add some abstract method to force constructor to have object.
}

public class ExtendPoints extends Points {

    /**
     * I want the abstract class to force this implementation to have
     *  a constructor with an object in it?
     * @param o
     */
    public ExtendPoints(Object o){

    }
}

推荐答案

您可以在抽象类中使用带有参数的构造函数允许匿名子类）。

You can use a constructor with a parameter in your abstract class (make it protected if you want to dis-allow anonymous subclasses).

public abstract class Points{
    protected Points(Something parameter){
        // do something with parameter
    }
}

实现类有一个显式的构造函数，因为它必须用一个参数调用超级构造函数。

Doing that, you force the implementing class to have an explicit constructor, as it must call the super constructor with one parameter.

但是，你不能强制覆盖类有一个带参数的构造函数。它总是可以这样伪造参数：

However, you cannot force the overriding class to have a constructor with parameters. It can always fake the parameter like this:

public class ExtendPoints extends Points{
    public ExtendPoints(){
        super(something);
    }
}

这篇关于java强制扩展类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！