11 Matching Annotations
  1. Jul 2021
  2. Jan 2021
  3. Dec 2020
    1. For example, an event handler callback that can be used to handle both fullscreenchange and fullscreenerror might look like this:
    1. A listener watches for an event to be fired. For example, a KeyListener waits for KeyEvents, a MessageListener waits for messages to arrive on a queue and so on. The handler is responsible for dealing with the event. Normally, listeners and handlers go hand-in-hand. For example, the KeyListener tells the ExitHandler that "the letter Q was pressed" and the handler performs logic such as cleaning up resources and exiting the application gracefully. Similary a ButtonClickListener would tell the same ExitHandler that the "Exit button was clicked". So, in this case you have two different events, two different listeners but a single handler.

      You can use the same handler for multiple events/listeners.

    2. The most basic difference is the association Listener is associated with Event Source (Ex: key board) Handler is associated with an Event (Ex: keydown)