addKeyListener() doesn't work for JPanel

Question

I am trying to make a game engine. I have made the Game class but the error resides in the KeyBoard class. Here I leave some code.

Class:: Game

Answer 1

Simply, your panel needs to be focusable. Add in wherever you create the panel:

panel.setFocusable(true);
panel.requestFocusInWindow();

Here's a SSCCE (I suggest asking questions with one of these in the future):

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

public class SimpleKeyTest {

    public static void main(String[] args) {

        Runnable r = new Runnable() {

            @Override
            public void run() {
                JFrame frame = new JFrame();
                JPanel panel = new JPanel();

                frame.getContentPane().add(panel);

                panel.addKeyListener(new KeyListener() {

                    @Override
                    public void keyTyped(KeyEvent e) {}

                    @Override
                    public void keyReleased(KeyEvent e) {}

                    @Override
                    public void keyPressed(KeyEvent e) {
                        System.out.println("Pressed " + e.getKeyChar());
                    }
                });

                panel.setFocusable(true);
                panel.requestFocusInWindow();

                frame.setSize(new Dimension(300, 300));
                frame.setVisible(true);
            }

        };

        SwingUtilities.invokeLater(r);

    }
}

Also, https://www.google.com/search?q=jpanel+keylistener

Answer 2

You can add the key listener to the JFrame, that's something I've done in the past. It's probably not a good idea however if you have other components in the JFrame.