KeyListener doesn't work

Question

I have the following two classes, the main-class (SamG) and the Panll-class. I have implemented the KeyListener in the Panll-class, but it doesn't seem to work.

public class SamG {
    public static void main(String[] args) {
        JFrame jf = new JFrame("My APP");
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setSize(800, 400);
        jf.setVisible(true);
        jf.pack();
        jf.setContentPane(new Panll());
    }   
}

public class Panll extends JPanel implements KeyListener {
    int x=100,y=100;
    boolean run=true;
    Panll() {
        addKeyListener(this);
    }

    @Override
    public void paint (Graphics g) {
        super.repaint();
        g.clearRect(0, 0, 800, 400);
        update();
        draw(g);
        try {
            Thread.sleep(17);
        } catch (InterruptedException ex) {
            Logger.getLogger(Panll.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public void update(){
        x++;
        y++;
    }

    public void draw(Graphics g){
        g.drawOval(x, y, 100, 100);
    }

    @Override
    public void keyTyped(KeyEvent e) {           
    }

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

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

Answer 1

you can't focus a JPanel without explicit allowing it with setFocusable(true); . if you add this line you can take you focus on the JPanel. if you then press any button the KeyListener works just fine

Answer 2

First never send main thread to sleep. Create a new Thread that periodically calls a repaint of your panel.
Second don't use paint() method to draw your stuff. Use the paintComponent() method instead.
Third add your KeyListener to your JFrame . Your JPanel won't receive the KeyEvents because it never gets the Focus.