Which of these is not one of the three parts to the event-handling mechanism in java?
event source
event action
event object
event listener

Event action

Explanation:Event-handling mechanism is the technique through which the  the management of any event is Java is controlled and coordinated. The event handler code is used for the managing of the mechanism and execution.

Event action is not a part of the event handling mechanism in the java because no such step comes under the code of event handler and rest other option are present in java event handler.

answer; ( blue box );