Events, Event Sources, and Event Listeners

• User interface events include key presses, mouse moves, button clicks, and so on
• Most programs don't want to be flooded by boring events
• A program can indicate that it only cares about certain specific events
• Event listener:
  • Notified when event happens
  • Belongs to a class that is provided by the application programmer
  • Its methods describe the actions to be taken when an event occurs
  • A program indicates which events it needs to receive by installing event listener objects
• Event source:
  • Event sources report on events
  • When an event occurs, the event source notifies all event listeners