Keylistener not working for JPanel

If you search this problem, you'll see that it is asked and has been solved many times.

KeyListeners need to be on the focused component to work. One solution is to give your component the focus after first making it focusable.
Better by a long shot however is to use Key Bindings. Google the tutorial on this.

Please have a look at my answer to this question for more on this, including many of the gory details.

For reference, I've create an example using your approach; while it works, it also suggests a focus problem elsewhere in your code. Key Bindings avoid this, as shown here.

Addendum: Here's my working key binding.

private static class TestPanel extends JPanel {

    private static final String LEFT = "Left";
    private Action left = new AbstractAction(LEFT) {
        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println(LEFT);
        }
    };
    private static final String RIGHT = "Right";
    private Action right = new AbstractAction(RIGHT) {
        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println(RIGHT);
        }
    };

    public TestPanel() {
        this.getInputMap().put(
            KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), LEFT);
        this.getActionMap().put(LEFT, left);
        this.getInputMap().put(
            KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), RIGHT);
        this.getActionMap().put(RIGHT, right);
    }
}

Original SSCCE:

import java.awt.EventQueue;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * @see https://stackoverflow.com/a/16531380/230513
 */
public class Test {

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new TestPanel());
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static class TestPanel extends JPanel implements KeyListener {

        public TestPanel() {

            this.addKeyListener(this);
            this.setFocusable(true);
            this.requestFocusInWindow();
        }

        @Override
        public void keyPressed(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
                System.out.println("Right");
            }

            if (e.getKeyCode() == KeyEvent.VK_LEFT) {
                System.out.println("Left");
            }
        }

        @Override
        public void keyTyped(KeyEvent e) {
        }

        @Override
        public void keyReleased(KeyEvent e) {
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Test().display();
            }
        });
    }
}

For receives key events on JPanel you must set focus:

setFocusable(true);
requestFocus();

the JPanel now has focus, so it receives key events

Keylistener not working for JPanel

Related

Recent Posts