Question

I know that that on can have a class declaration in a method of class.
Eg. We can have anonymous class declaration for event handling in a method body.

But I want to know that same way can I have Interface declaration in a method in a class.

What is use of that?

Answer 1

I’ assuming you are refering to returning an interface for a method?

Short answer: Yes.

Why?

Here’s a good post.
Why we return type Mostly Interface rather than Class?

Excerpt:

The benefit is that returning an
interface makes it possible to change
the implementation later on. E.g., you
might decide after a while that you’d
much rather use a LinkedList instead
of an ArrayList…..