Is it possible to apply inheritance to a Singleton class?

Question

Today I faced one question in interview. Is it possible to apply inheritance concept on Singleton Classes? I said since the constructor is private, we cannot extend that Singlet

Answer 1

A private constructor is visible to other inner classes of that singleton class. So yes, technically a singleton class with a private constructor can be extended by its inner class. But why would you do something like that is beyond me.