强制子类实现抽象子类

发布于 2024-08-23 00:15:45 字数 463 浏览 6 评论 0原文

我想在 java 中创建一个抽象类，强制其所有子类实现 SwingWorker （加上 SwingWorker 的抽象 doInBackground() 和完成（））。

在 AbstractClass 中 -

abstract class Task extends SwingWorker<Void, Void>{};

我希望这会导致编译器在扩展类未实现它时抛出异常，但事实并非如此。

我也不太确定如何表明我正在重写这个抽象类。我是否在 ConcreteClass 中重新声明它，如下所示？

class Task extends SwingWorker<Void, Void>{
  ...
}

或者其他方式？

感谢您的帮助！

原文

I want to create an abstract class in java that forces all its subclasses to implement a SwingWorker (plus the SwingWorker's abstract doInBackground() and done()).

In AbstractClass -

abstract class Task extends SwingWorker<Void, Void>{};

I would expect this to cause the compiler to throw an exception when an extended class doesn't implement it, but it doesn't.

I am also not quite sure how I would go about indicating that I'm overriding this abstract class. Do I redeclare it in the ConcreteClass as follows?

class Task extends SwingWorker<Void, Void>{
  ...
}

or some other way?

Thanks for all your help!

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Spring初心 2024-08-30 00:15:45

您还需要将这些方法声明为抽象方法，如下所示：


abstract class Task extends SwingWorker {
    @Override
    protected abstract Void doInBackground();
    @Override
    protected abstract void done();
};

you need to declare the methods also as abstract, like this:


abstract class Task extends SwingWorker {
    @Override
    protected abstract Void doInBackground();
    @Override
    protected abstract void done();
};

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浮世清欢 2024-08-30 00:15:45

doInBackground() 在 SwingWorker 中是抽象的，因此 Task 的任何具体子类都应该提供一个实现。

然而，done() 在 SwingWorker 中并不是抽象的，因此不需要新的实现。如果你想强制你的子类重新实现它，你需要：

abstract class Task extends SwingWorker<Void, Void>{
    @Override
    protected abstract void done();
}

要创建具体的子类，只需扩展 Task 就像扩展任何其他类一样，并使用实现覆盖抽象方法：

class SubTask extends Task {
    @Override
    protected void done(){
        //implementation
    }

    @Override
    public Void doInBackground(){
        //implementation
    }
}

doInBackground() is abstract in SwingWorker, so any concrete subclass of Task should have to provide an implementation.

done(), however, is not abstract in SwingWorker, so no new implementation is needed. If you want to force your subclasses to reimplement it you need to:

abstract class Task extends SwingWorker<Void, Void>{
    @Override
    protected abstract void done();
}

To create the concrete subclass, just extend Task like you would extend any other class, and override the abstract methods with implementations:

class SubTask extends Task {
    @Override
    protected void done(){
        //implementation
    }

    @Override
    public Void doInBackground(){
        //implementation
    }
}

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