764: Mainline

In the remainder of this chapter, you see how to add a model and an observer to the example of Segment 726 so as to ground the illustration of Segment 761 in a program that exhibits all the elements described in Segment 760:

• The model will be a Movie class instance, with the Movie class modified so as to extend the Observable class.
• The observer will be an instance of a new MovieObserver class, which defines a method, that, when activated, fetches a movie's rating from the application's movie instance—the model—and relays that rating to the application's meter instance—the view.