JAVA: Popup menu in diffrent class then main Applet, how to repaint()?

Valkyrie_of_valhalla · 10-22-2009, 11:27 AM

In an attempt to better organise my code, I decided to have a main class,

Code:

public class MainClass extends Applet implements MouseListener, MouseMotionListener

and a second DrawMenu class,

Code:

public class DrawMenu extends PopupMenu implements MouseListener, MouseMotionListener, ActionListener

And it works perfect, except that after issuing a command in the menu, I need a repaint() in MainClass... ofc I can't create an instance of MainClass in DrawMenu, can't call MainClass.repaint() as it is not static... so I'm kind of stuck. Is there a proper way to do this, or do I have to put them in the same class?

gzunk · 10-22-2009, 06:30 PM

I assume that your first class creates the instance of the second class.

In which case, simply pass a reference of MainMenu to DrawMenu - either in the constructor, or as a method call after the constructor, and store the reference in an instance variable.

Then, when you need to call MainMenu "repaint" in DrawMenu, you can call it - by using the reference you have saved.

WARNING - TECHNICAL ALERT
But if I was to be honest, I would have to say that this will only work if the routine in DrawMenu was being invoked in the GUI thread, but it might not be - so ignore this caveat :-)

Valkyrie_of_valhalla · 10-24-2009, 03:14 PM

Thanks for your reply

Found another solution, sort of... Made MainClass runnable, and in it, created a "boolean modified", which will be set true if i click something in the menu in the other class.
Then I have a...

Code:

    public void run(){
        while (true){
            System.out.print("");
            if (modified){
                repaint();
                modified=false;
            }
        }
    }

What's with the System.out.print("");? Well, apparently, if I don't have something outside the if that executes on each run, it doesn't work...

So... new question: why is this, and how is it usually done?