在Java中实现接口并覆盖方法? [英] Implement an interface and override methods in Java?

问题描述

为什么必须重写接口的所有方法?

Why do you have to override all methods of an interface?

例如，如果我有

public class Foo extend JFrame implements ActionListener, KeyListener {
      foo(){
      }
    @Override
    public void keyPressed(KeyEvent arg) {          
    }

    @Override
    public void keyReleased(KeyEvent arg) {
}

    @Override
    public void keyTyped(KeyEvent arg) {        
    }
}

我将有很多我什至不会使用的方法，有没有一种方法可以删除未使用的已实现方法，例如，如果我计划从界面中使用一种方法

I'm going to have lots of methods I won't even be using, is there a way to remove the un used implemented methods, for instance if i plan to use one method from the interface

我也不想使用抽象，因为这意味着我无法创建对象的实例(至少我的编译器这样说)

I don't want to use abstract either, as this means I can't create an instance of the object (at least my compiler says so)

推荐答案

具体类必须始终实现接口的所有方法.如果尚未扩展JFrame，则可以扩展KeyAdapter.它为KeyListener实现了空方法，以避免将其写出.您可以在Foo类内部使用匿名类，如下所示:

Concrete classes must always implement all of the methods of an interface. If you weren't already extending JFrame you could extend KeyAdapter. It implements empty methods for KeyListener to avoid writing them out. You could use an anonymous class with that inside of your Foo class like this:

addKeyListener(new KeyAdapter() {
    public void keyTyped(KeyEvent e) {
        // handle typed key here
    }
});

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