Abstract class and an Interface

Question

Write difference between an Abstract class and an Interface.

Answer 1

Abstract Class :

a) A class is able to extend only one abstract class.
b) Abstract classes must have subclasses.
c) Members of abstract class may be private as well as protected.
d) Methods in the abstract class may be abstract as well as concrete.
e) Any class is able to extend an abstract class.
f) Class extending the abstract class may or may not execute any of its method.
g) There can be a constructor for the abstract class.
h) An abstract class can implement the methods.

Interface:

a) Several interfaces can be implemented by a class,
b) Interfaces should have implementations by classes.
c) An interface can have only public members.
d) All methods in an interface must be abstract.
e) Only an interface is able to extend another interface.
f) All methods of interface need to be implemented by a class implementing that interface.
g) Interface does not have constructor.
h) Interfaces cannot contain body of any of its method.