This is ensured by requiring that all event listeners for a particular type of event implement a corresponding interface. The Java 1.1 event model defines a large number of event classes. The figure below shows the heirarchy of these event classes. If you will notice carefully, different classes of events are represented by different Java classes. This method returns the object that originated the event.
Every event has a source object, from which the event originated.
This method returns a reference to that source. This is the superclass of all the delegation model event classes. This method returns the ID of the event. An event's ID is an int that specifies the exact nature of the event. This value is used to distinguish the various types of events that are represented by any event class.