Adanced Java Programming

Event Handling

Smt.M.Jeevana Sujitha

Assistant Professor

​

Department of Computer Science and Engineering

SRKR Engineering College, Bhimavaram, A.P. - 534204

OBJECTIVES

The Objective of this lecture is

• To learn about Event Handling in AWT.

Event Handling

• Event: Action that can be performed on the component is called an event.
• Event describes the change in state of source.
• Events are generated as result of user interaction with the graphical user interface components.
• For example, clicking on a button, moving the mouse, entering a character through keyboard are the activities that causes an event to happen.

Event Handling

• Event Handling: Event Handling is the mechanism that controls the event and decides what should happen if an event occurs.
• This mechanism have the code which is

known as event handler that is executed when an event occurs.

• Java Uses the Event Delegation Model to handle the events. This model defines the standard mechanism to generate and handle the events.

Event Handling

• The Event Delegation Model has the following two key participants.
• Source: The source is an object on which event occurs.
• It is responsible for providing information of the occurred event to its handler.

• Listener: It is also handler.

known as event

for generating

• Listener is responsible response to an event.

Event Handling

Steps involved in Event Handling:

• If the clicks the button then the event is generated.
• Now the object of concerned event class is created automatically.
• Event object is forwarded to the method of registered listener interface.
• The method is now get executed.

THANK YOU