Differentiate between an abstract class and an interface

Abstract Class:

• A class can extend only one abstract class
• The members of abstract class can be private as well as protected.
• Abstract classes should have subclasses
• Any class can extend an abstract class.
• Methods in abstract class can be abstract as well as concrete.
• There can be a constructor for abstract class.
• The class extending the abstract class may or may not implement any of its method.
• An abstract class can implement methods.

• A class can implement several interfaces
• An interface can only have public members.
• Interfaces must have implementations by classes
• Only an interface can extend another interface.
• All methods in an interface should be abstract
• Interface does not have constructor.
• All methods of interface need to be implemented by a class implementing that interface.
• Interfaces cannot contain body of any of its method.