• Events – Objects that describe what happened
• Event sources – The generator of an event
• Event handlers – A method that receives an event object, deciphers it, and processes the user’s interaction

• Hierarchical model (JDK 1.0)
  • Advantages: Uses object-oriented principles
  • Disadvantages: An event can be handled only by the component from which it originated or by one of the containers of the originating component. To handle events, you must either subclass the component that receives the event or create a handleEvent() method at the base container.
• Delegation model (JDK 1.1 and beyond)
  • Advantages:
    • Events are not accidentally handled
    • You can create and use filter (adapter) classes to classify event actions
    • There is better distribution of work among the classes
  • Disadvantage: You should not combine two event models

java.util.EventObject

	java.awt.AWTEvent
		java.awt.event
			ActionEvent
			AdjustmentEvent
			ComponentEvent
				ContainerEvent
				FocusEvent
				InputEvent
					KeyEvent
					MouseEvent
				WindowEvent

			ItemEvent
			TextEvent


	java.beans.beancontext
		BeanContextEvent
		...

• WindowListener
• ContainerListener
• TextListener
• ActionListener-- button, textfield
• ItemListener -- radio button, checkbox, choice, list

• Multiple listeners cause unrelated parts of a program to react to the same event
• All registered listeners call their handlers when the event occurs

• KeyAdapter
• WindowAdapter
• MouseMotionAdapter
• MouseMovingAdapter
• ContainerAdapter