java - JPanel KeyListener 不工作

Question

import javax.swing.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class AnaPencere{
    JFrame pen;
    AnaPencere(){
        pen = new JFrame("Ana Pencere");
        pen.setSize(613, 253);
        pen.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pen.setLocationRelativeTo(null);
        pen.setResizable(false);
        pen.add(new Cizim());
        pen.setVisible(true);
    }


    private class Cizim extends JPanel{

        private Cizim() {
            this.addKeyListener(new KeyAdapter() {
                @Override
                public void keyReleased(KeyEvent e) {
                    System.out.println(e.getKeyCode());
                }
            });
        }
    }
}

当我运行项目时，一切都按预期工作，但是当我按下某个键时，我在控制台中看不到预期的结果

Answer 1

• 为 JPanel 添加 setFocusable(true) 并添加 KeyListener

• 也许没有理由寻找Focus，setFocusable，改用KeyBindings

• 在那里你可以set programatically the focus in the components hierarchy