Question

I am trying to use the MVC design.

In the model I wanted a method like this

public boolean changeSomeData(...){
    boolean b;
    //create a dialog with an OK button
    return b;
}

I want the method to return TRUE if the changes were actually made. The changes are done inside the actionPerformed method of the OK button.

My problem is that I can’t write b=true; inside the actionPerform of the OK button, because I have to declare b as final in order to use it in the actionPerformed().

What I did is creating a class

private class MyBoolean {
    boolean b;
}

and then

public boolean changeSomeData(...){
    MyBoolean myBoolean;
    //create a dialog with an OK button
    actionPerformed(){
        //make changes in the data
        myBoolean.b=true;
    }
    boolean b = myBoolean.b;
    return b;
}

But I don’t feel good about this solution and I wanted to know if it is correct what I did and if there is a better solution.
Should I better throw an exception if the changes aren’t made? (for example, if the user clicks “cancel” instead of “ok”)

Answer 1

In the model I wanted a method like this … //create a dialog with an OK button

I’d say this is a flaw already, since the model should not do anything with views directly.

A better approach would be to open the dialog (using the controller), register the controller for the ActionEvent of “OK” (and thus actionPerformed) and then do whatever changes should be done in that method.

Edit:

You might want to consider the following rough approach:

The views register themselves or associated classes to the model as listeners. Whenever the model is changed it fires events to notify the views of the change.

The controller registers itself on the views and is notified when the views change. If a user changes data, the controller then might open the dialog and only commit the changes of the user signals “OK”. Thus the model has never to check itself if data needs to be changed. That is actually the controller’s task and if the controller passes changes to the model, it should apply them.