CODEWITHSUNDEEP
javakeylistener
Rajakumar
Rajakumar

Reputation: 139

KeyListener doesn't work

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) {    
    }
}

Upvotes: 0

Views: 458

Answers (2)

ArcticLord
ArcticLord

Reputation: 4039

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.

Upvotes: 1

XtremeBaumer
XtremeBaumer

Reputation: 6435

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

Upvotes: 1

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