java - 简单的 KeyListener 不起作用

Question

我正在用 Java 开发一个非常简单的项目，试图了解如何使用 KeyListener。 我创建了一个 Main 类和一个 KeyListener、MouseListener 类。我希望在按下键盘按键时发生一些事情。到目前为止，当我点击时唯一有效的是“Hello”。

这是我的代码:

import javax.swing.JFrame;
import javax.swing.JPanel;

public class KeyPractice{

    public static void main(String[] args) {

        JFrame frame = new JFrame();
        JPanel panel = new JPanel();

        panel.addKeyListener(new KeyEar());
        panel.addMouseListener(new KeyEar());

        frame.add(panel);

        frame.setVisible(true);
        frame.setSize(400, 400);
    } 
}

还有 Keylistener 类......

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

public class KeyEar implements KeyListener, MouseListener {

    public KeyEar(){

    }

    @Override
    public void mouseClicked(MouseEvent arg0) {
        System.out.println("Hello");
    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub
    }

    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub
    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub
    }

    @Override
    public void mouseReleased(MouseEvent arg0) {
        // TODO Auto-generated method stub
    }

    @Override
    public void keyPressed(KeyEvent arg0) {
        System.out.println("Hello");
    }

    @Override
    public void keyReleased(KeyEvent arg0) {
        System.out.println("Hello");
    }

    @Override
    public void keyTyped(KeyEvent arg0) {
        System.out.println("Hello");
    }
}

Answer 1

• JPanel无法聚焦JComponent ，必须添加可聚焦或与 KeyEvents 交互的 Object/JComponents

• KeyListener不正确listener for Swing JComponents ，对于 Swing 替换为 KeyBindings