Event Listener Object

When a GUI program is running, the user generates an event by interacting with a GUI component. The following are some ways to generate an event:

• Moving the mouse.
• Clicking the mouse.
• Clicking on a button.
• Typing some text into a text area.

For a program to respond to an event there must be an event listener object for it. The event listener object contains listener methods for the various types of events.

A program can ignore events. For example the programs of the previous chapter ignored nearly all events. If there is no listener for an event, the event is ignored.