Can we write abstract class without method If yes what is use
Answer: Yes. An empty abstract class is very much equivalent to an interface except that it can extend a class:
This pattern is called Marker interface.
If you answer sometimes we need a base class for implement polymorphism then interviewer will ask you an interface won’t do. My answer would be:
Yes, main difference is that you can implement some code in your base class, or define some attributes.