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Thread: KeyListener won't listen

  1. #1
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    Default KeyListener won't listen

    Why won't my "player1" move???
    Class with main
    import java.awt.Color;
    import java.awt.event.KeyEvent;
    import java.awt.event.KeyListener;
    import javax.swing.JFrame;
    import javax.swing.JPanel;
     
     
    public class Spelplan extends JPanel implements KeyListener
    {
     
        Gubbe player1;
     
        int x = 100;
        int y = 100;
     
        public Spelplan()
        {
            setLayout(null);
            player1 = new Gubbe(30, 50, x, y);    
            this.setLocation(20, 30);
            add(player1);
            player1.addKeyListener(this);
            this.setBackground(Color.black);
     
        }
     
        public static void main(String[] args) 
        {
            JFrame f = new JFrame();
            f.setSize(300,300);
            f.setLocation(200,200);
            f.setTitle("RogueTest");
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            Spelplan p = new Spelplan();
            f.add(p);
            f.setVisible(true);
     
        }
     
        public void keyTyped(KeyEvent e)
        {
     
        }
     
        public void keyPressed(KeyEvent e)
        {
     
            if(e.getKeyCode() == 38)
            {
                System.out.println("Pressed");
                y = y + 10;
            }
     
            repaint();
        }
     
        public void keyReleased(KeyEvent e)
        {
     
        }
     
    }//class

    Other class
    import java.awt.Color;
    import java.awt.Dimension;
    import java.awt.Graphics;
    import javax.swing.JPanel;
     
     
    public class Gubbe extends JPanel
    {
        private int bas, hojd, xpos, ypos;
     
     
     
        public Gubbe(int b, int h)
        {
         bas = b;
         hojd = h;
         this.setBackground(null);
         this.setPreferredSize(new Dimension(bas, hojd));
        }
     
     
     
        public Gubbe(int bas, int hojd, int xpos, int ypos)
        {
            this.bas = bas;
            this.hojd = hojd;
            this.xpos = xpos;
            this.ypos = ypos;
            this.setSize(bas, hojd);
            this.setLocation(xpos - bas/2, ypos);
     
     
        }
     
     
     
        @Override
        public void paintComponent(Graphics g)
        {
            int x[] = { bas/2, 0, bas};
            int y[] = { 0, hojd, hojd };
     
            g.setColor(Color.red);
            g.fillOval(10,20, 20, 20);
     
     
     
        }
     
     
     
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: KeyListener won't listen

    Does the panel with the listener have the focus?

    Move your debugging print statement outside of the if clause to see if the method is being called.

    What key is tested for here? Why not use the VK_... variable vs the 38?

    if(e.getKeyCode() == 38)
    Last edited by Norm; June 22nd, 2011 at 06:50 AM.

  3. #3
    Administrator copeg's Avatar
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    Default Re: KeyListener won't listen

    Keylisteners require the component to have focus. An alternative would be to use KeyBindings: How to Use Key Bindings (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

  4. #4
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    Default Re: KeyListener won't listen

    I tried using the .setFocusable(true) in "public Spelplan". I also kept the printline "Pressed" inside the if-statement. Now it says "Pressed", but the component does not move.

  5. #5
    Super Moderator Norm's Avatar
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    Default Re: KeyListener won't listen

    but the component does not move.
    What will make it move? What statement is supposed to make it move?

  6. #6
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    Default Re: KeyListener won't listen

    Quote Originally Posted by Norm View Post
    What will make it move? What statement is supposed to make it move?
    Because I change the value of y:
    y = y + 10;

    Or?? wouldn't that work?

  7. #7
    Super Moderator Norm's Avatar
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    Default Re: KeyListener won't listen

    What difference does changing the value of y make to where the component is?

  8. #8
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    Default Re: KeyListener won't listen

    Quote Originally Posted by Norm View Post
    What difference does changing the value of y make to where the component is?
    Because the Y value is the components Y - value. When I change the Y value
    int y = 100;
    the component is changing it's position. Then I just thought it sounded reasonable that it would also change position if I made the value change by pressing the "up" - key. It did not do that

  9. #9
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    Default Re: KeyListener won't listen

    Yeah, I made it work!

    if(e.getKeyCode() == 38)
            {
                y = player1.getY();
                System.out.println("Pressed");
    //            y = 200;
                player1.setLocation(x, y -= 10);
                repaint();
     
            }

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