无法使键盘侦听器正常工作 [英] Cannot make a keylistener work

问题描述

我有public class MainFrame extends JFrame implements ActionListener {

，然后再输入:

public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == e.VK_LEFT) {
        int x = ball.getX() + 1;
         ball.setX(x);
        }
        }

但是，我认为应该没有反应.

however it does not seem to respond when I believe it should.

如果我添加keylistener而不是actionlister，我将无法编译我无法理解的代码.我是Java的新手，但我已经习惯了C#

If I add keylistener instead of actionlister I cannot compile which I can't understand. I'm new to java however i'm used to C#

推荐答案

1. 您需要实现java.awt.event.KeyListener而不是ActionListener来监听关键事件.
2. 您需要通过调用addKeyListener(...)在要监听的元素(框架)上注册监听器.

1. You need to implement java.awt.event.KeyListener not a ActionListener to listen for key events.
2. You need to register your listener on the element (frame) you want to listen on by invoking addKeyListener(...).

示例:

public class TestFrame extends JFrame implements KeyListener {

    public static void main(String[] args) throws FileNotFoundException {
        TestFrame testFrame = new TestFrame();
        testFrame.setSize(100, 100);
        testFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        testFrame.addKeyListener(testFrame);
        testFrame.setVisible(true);
    }

    @Override
    public void keyTyped(KeyEvent e) {    }
    @Override
    public void keyPressed(KeyEvent e) {
        System.out.println(e);
    }
    @Override
    public void keyReleased(KeyEvent e) {   }
}

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