This interface defines the update( ) method required for an object to observe subclasses of Observable . An Observer registers interest in an Observable object by calling the addObserver( ) method of Observable . Observer objects that have been registered in this way have their update( ) methods invoked by the Observable when that object has changed. This interface is conceptually similar to, but less commonly used than, the EventListener interface and its various event-specific subinterfaces. public interface Observer { // Public Instance Methods void update (Observable o , Object arg ); } Passed ToObservable.{addObserver( ) , deleteObserver( )} |