What are the key differences between an abstract class and an interfac

What are the key differences between an abstract class and an interface.

Answer»

The key DIFFERENCES between an abstract class and an interface are as follows:

COMPARISON Parameter	Abstract Class	Interface
Usage	Abstract Classes are extended.	Interfaces are implemented.
Final Variables	Abstract classes can or cannot contain final variables and non-final variables	In interfaces, all variables are final by default.
Accessibility of DATA Members	Abstract classes can be PRIVATE, public, etc.	Interfaces are public by default.
METHODS	Abstract, as well as other types of methods, are allowed in abstract classes.	Only abstract methods can be present in an interface.
Implementation	Abstract classes cannot be implemented.	Interfaces can be implemented.