Abstract class and interface differ based on following parameters:
Methods
An abstract class can
have both abstract methods and concrete methods.
An interface has all the
methods as abstract. Methods in interface is 100% abstract.
Keyword used to declare
To declare abstract
class use the keyword ‘abstract’.
Example abstract
class dummyClass{//abstract methods, methods}
To declare interface use
the word ‘interface’.
Example interface dummyInterface{//abstract method
(s)}
Method declaration
In abstract class, to
declare any method as abstract use of abstract keyword is mandatory.
In interface, to declare
methods as abstract use of abstract keyword is optional. Methods in interface is by
default abstract.
Inheritance Supported
Being a class, an
abstract class cannot inherit multiple classes. It can only inherit one class.
An Interface can extend
(or inherit) multiple interfaces.
What can be extended?
An abstract class can
extend either normal class or abstract class.
Interface can extend
only interface but not a class.
Variable type & Access modifier
An abstract class can
have static, non-static, final or non-final variable with any access modifier.
An interface can only
have public static final variable. In interface variable is constant.
