Adapter

Adapter is a class in Java that implements an interface with a set of dummy 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.

Adapter is also a design pattern. The Adapter pattern is used so that two unrelated interfaces can work together. The joining between them is called an Adapter. This is something like we convert interface of one class into interface expected by the client. We do that using an Adapter, for more detail refer java design patterns adapter pattern.