无法从内部类调用重绘

Question

I have a outer class which extends JPanel and holds a paintComponent method which just draws an image, my inner class is also a JPanel and is my mouse event listener. The events change the way the drawing looks by calling the repaint after the changed, but it doesn't seem like the repaint is getting called properly

    public class FollowingEyes extends JPanel
{
    private Eye eye;
    private Eye eye2;
    private final int HEIGHT = 500;
    private final int WIDTH = 500;
    private OtherPanel panel;
    public FollowingEyes()
    {

        eye     =   new Eye((WIDTH/2)-50,50);
        eye2    =   new Eye((WIDTH/2)+50,50);     
        panel   =   new OtherPanel();
        setPreferredSize(new Dimension(500,500));
       addMouseListener(panel);
       addMouseMotionListener(panel);
    }

        public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        eye.draw(g);
        eye2.draw(g);              
    }



    private class OtherPanel extends JPanel implements MouseListener, MouseMotionListener
    { 



           @Override
        public void mouseEntered(MouseEvent e)
        {
            System.out.println("Mouse entered..");
            eye.look(true);
            eye2.look(true);
            repaint();

        }
        @Override
        public void mouseExited(MouseEvent e)
        {
            System.out.println("Mouse exited..");
            eye.look(false);
            eye2.look(false);
            repaint();
        }

        @Override
        public void mouseClicked(MouseEvent e){};
        @Override
        public void mousePressed(MouseEvent e){};
        @Override
        public void mouseReleased(MouseEvent e){};

        @Override
        public void mouseMoved(MouseEvent e)
        {
            eye.setAngle(e.getX(), e.getY());
            eye2.setAngle(e.getX(), e.getY());
            repaint();
        }

        @Override
        public void mouseDragged(MouseEvent e){};


    }

Answer 1

The problem is that your eyes ( eye and eye2 ) are added to the FollowingEyes panel but when mouse is moved, you call repaint() on the OtherPanel thus eyes will not be repainted.

Try calling repaint() of the FollowingEyes instance:

eyes.repaint();

Also another problem is that the eyes attribute of OtherPanel is initialized with a new FollowingEyes instance and not with the enclosing instance. You should initialize it with FollowingEyes.this or pass it as a constructor argument (that way you will be able to make the OtherPanel class an external class).

Answer 2

To start with, the field eyes is unused therefore unessecary. Also, if you want to call the repaint on the whole FollowingEyes from OtherPanel , use FollowingEyes.this.repaint() . What you currently have is repainting only OtherPanel .