Question

I have a class let’s say MyJFrame which represent the GUI of my application. It implements the interface Observer and override the method update.

public class MyJFrame extends JFrame implements Observer{
  ...
  public void update(Observable arg0, Object arg1){
     ...
  }
}

Now I want to make also my JFram an Observable object but I can’t because it already extend the class JFrame. I tried to create a variable of type Observable in my class.

public class MyJFrame extends JFrame implements Observer{
  Observable observable = new Observable();

The problem here is that I can add Observer to this observable field and I can also notify the observer but I cannot invoke the method setChanghed() (because it is declared as protected) which has to be called before the notification.

Do you have any idea about I can implement it?

Thanks!!

Answer 1

Extend Observable and declare setChanged() public.