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Java Jpanel Repaint/update probleme

I can't say that I've read all your code, but your model never notifies the view. I mean nowhere inside of the model class's code is the notifyView() method called. It should be the model's responsibility to call this whenever its state is changed.

Note that this:

car.update(car.getGraphics()); //
<< the Problem is HERE

Should not be used as the Graphics obtained is not stable.

Also, your model holds view components, an ArrayList of Car, a class that extends JPanel, another thing that should never occur as the model should be completely ignorant of the view, with the exception being that it knows that some things may be listening to it, and it needs to notify those things, and that's it. Instead your Model should hold an ArrayList of non-view, non-JPanel logical Car objects.

You state:

In the model i have the method: public void notifyView() which is called by the car's method public void Move() , That means whenever the thread calls the move method of the car, it calls the notifyView of the model

No, the Car should not be calling this method -- only the model itself should call this when its state is changed.

Also, I see that you've got very dangerous code using Thread#suspend() and Thread#resume() method calls. These methods have been deprecated as they've been found to be dangerous. To find out why, please check the API for Thread as well as this useful article. You will most definitely want to avoid their use.


  • Make Car a logical non-GUI class that knows its position and can have its position changed.
  • Override your drawing JPanels protected void paintComonent(Graphics g) method and use the Car information from the model to draw the Cars. In other words, use the state of the model to affect the state of the view.
  • Use a Swing Timer instead of a background thread, to change your Car positions.
  • Have the model and only the model call the notifyView method when its state has been changed.

Your main bug is here:

class Car extends JPanel {
    private int id, x, y, vitess;


    public int getX() {
       return x;

    public int getY() {
       return y;

You're inadvertently overriding the Car JPanel's getX and getY methods, messing up the location of these components. This is another reason to avoid overriding Swing components unless necessary -- to avoid these hidden side effects.

Get rid of or rename these methods.

Categories : Java

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