java.lang.Object | +----java.util.Observable
public class Observable
extends Object
This class represents an observable object, or "data" in the model-view paradigm. It can be subclassed to represent an object that the application wants to have observed.
An observable object can have one or more observers. After an observable instance changes, an application calling the Observable's notifyObservers method causes all of its observers to be notified of the change by a call to their update method.