If you extend one of the Swing components to add functionality, or
indeed, build your own component from scratch, you need to handle
event listeners for any events you might generate. The
EventListenerList class is designed to aid in that
task. This class is similar in many ways to the
AWTEventMulticaster; however, it supports any type
of listener and assumes you’ll use only the appropriate
listeners for a given event type. Unlike the AWT multicaster, it does
not assume all of the listeners support the same events.
KeyStroke class can also help handle keyboard
events. Rather than listening to every key that gets pressed and
throwing out the things you don’t care about, you can use the
KeyStroke class to register specific actions with
If your component generates events, it
must contain methods to add and remove interested listeners.
Following the JavaBeans design patterns, these are the
methods. Typically you store the listeners in a vector, and then use
the vector as a rollcall for who to send events to when the time
comes. This is a very common task for components that generate
events, and the
EventListenerList can help lift
some (but certainly not all) of the burden of coding the event
EventListenerList stores listeners as pairs of objects, one object to hold the listener’s type and one to hold the listener itself. At any time, you can retrieve all of the current ...