Question

I have been facing so many problem using the anonymous class like I can’t perform the instanceOf test neither can I implements multiple interface, so could someone please explain what I can or can not do with the anonymous class in java ?

Answer 1

The purpose of an anonymous inner class is to extend and instantiate an existing class or implement a single interface in one step.

Its limitations can be derived from the above:

• Only one non-final class can be extended or one interface implemented.
• Only final local variables of the enclosing method can be accessed. (This is due to the fact that normal local variables will be out of scope by the time any methods of the inner class will be invoked.)
• You can’t define a constructor. (The class has no name.)

If you need multiple interfaces, you can use a local inner class, which is like a normal inner class, with its own name, but defined within a method. I have to admit I’ve never seen it used in practice and I see very little reason for anyone to do so, hopefully someone will come up with an example.