2. ProgrammingLanguages Programming Languages

3. The Java Event Model In this lesson, we look at the content of these objects and how they are processed in Java 2.

4. Events In Java 2 Java 2 handles events that are generated in a graphical component by delegating to objects that have registered an interest in that type of event.Java 2 handles events that are generated in a graphical component by delegating to objects that have registered an interest in that type of event. Event observer objects are called listeners and implement listener interfaces.Event observer objects are called listeners and implement listener interfaces. The observable component that generates events, and the observer is the object that has registered to receive events.The observable component that generates events, and the observer is the object that has registered to receive events.

5. The root of the Java 2 event hierarchy is the EventObject classThe root of the Java 2 event hierarchy is the EventObject class The Event Hierarchy java.uti1.EventObject +--java.awt.AWTEvent +-- java.awt.event.ActionEvent +-- java.awt.event.AdjustmentEvent +-- java.awt.event.AncestorEvent +-- java.awt.event.ComponentEvent +-- java.awt.event.InputMethodEvent +-- java.awt.event.InternalFrameEvent +-- java.awt.event.InvocationEvent +-- java.awt.event.ItemEvent +-- java.awt.event.TextEventjava.uti1.EventObject +--java.awt.AWTEvent +-- java.awt.event.ActionEvent +-- java.awt.event.AdjustmentEvent +-- java.awt.event.AncestorEvent +-- java.awt.event.ComponentEvent +-- java.awt.event.InputMethodEvent +-- java.awt.event.InternalFrameEvent +-- java.awt.event.InvocationEvent +-- java.awt.event.ItemEvent +-- java.awt.event.TextEvent

6. Events that descend from ComponentEvent java.awt.event.ComponentEvent +-- java.awt.event.ContainerEvent +-- java.awt.event.FocusEvent +-- java.awt.event.PaintEvent +-- java.awt.event.WindowEvent +-- java. awt.event.InputEvent +-- java.awt.event.MouseEvent +-- java.awt.event.KeyEventjava.awt.event.ComponentEvent +-- java.awt.event.ContainerEvent +-- java.awt.event.FocusEvent +-- java.awt.event.PaintEvent +-- java.awt.event.WindowEvent +-- java. awt.event.InputEvent +-- java.awt.event.MouseEvent +-- java.awt.event.KeyEvent For typical programming, user probably works with only a few of the events: ComponentEventFor typical programming, user probably works with only a few of the events: ComponentEvent

7. Listeners And Adapters Each class that can generate one of these events has a method to add a listener for that event.Each class that can generate one of these events has a method to add a listener for that event. Java defines a number of listener interfaces that are named according to the events they process.Java defines a number of listener interfaces that are named according to the events they process. Java also includes classes called adapters that provide empty methods for the more complex interfaces.Java also includes classes called adapters that provide empty methods for the more complex interfaces.

8. Events, Listener interfaces, and Adapter classes.

9. An Java Example with Event-Handling This Java Applet has a button, with caption “Click Me”. When user clicks the button, it beeps.This Java Applet has a button, with caption “Click Me”. When user clicks the button, it beeps.

10. An Java Example with Event-Handling