An adapter is one of the classic design patterns. It is also a class in Java that implements an interface with a set of dummy methods.
It lets you rapidly implement an interface. It also lets your class continue to work
ever if the underlying interface acquires new methods. You can then subclass the
adapter class and override just the methods you need. If you implemented the
interface directly, you would have to write all the dummy methods yourself. Most
commonly an adapter is used to help you rapidly construct your own Listener class to
field events. By extending an adapter class, with KeyAdapter, FocusAdapter, WindowAdapter etc. you don’t have to write methods for events
you are not interested in handling.