Abstract classes and Interfaces

Question 1

Abstract class

Answer 1

Class which cannot be instantiated on its own. It must be extended by another class.

Question 2

Why Use abstract classes (3)

Answer 2

Common set of features for all derived classes
Prevents users from handling objects which are too generic
We don’t have to give a full implementation for the class - usually give most of it and let users override

Question 3

Interface class

Answer 3

Set of methods and constants identified with a name. This class also cannot be instantiated

Question 4

Why use Interfaces?

Answer 4

To separate the specification available to the user from implementation