Observable in Java

Question

I\'m trying to understand the Observer and the Observable.

Here\'s an example that I\'m trying to figure out:

public class IntegerDataBag extends Obs         


        

Answer 1

1. Yes. addObserver is a method in the Observable abstract class. See Observable in the Java documentation.
2. It is added to a list in Observable.
3. A call to notifyObservers will do nothing until setChanged is set.
4. You might have multiple Observables in the same application.
5. Observer is a common design pattern. The usual example is when you have a Model and multiple Views. Each View is an Observer on the Model; if the Model changes, the Views get updated.