JPanel KeyListener Not Working

问题

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());
                }
            });
        }
    }
}

When I run the project, everything works as expected, but when I press a key, I am not seeing the expected result in the console

回答1:

• add setFocusable(true) for JPanel with added KeyListener

• maybe there no reason to hunting for Focus, setFocusable, use KeyBindings instead

• there you can to set programatically the focus in the components hierarchy

来源：https://stackoverflow.com/questions/15599748/jpanel-keylistener-not-working