Difference between Abstract class and Interface

In this post will discuss about difference between Abstract class and Interface

	abstract Classes	Interfaces
1	abstract class can extend only one class or one abstract class at a time	interface can extend any number of interfaces at a time
2	abstract  class  can extend from a class or from an abstract class	interface can extend only from an interface
3	abstract  class  can  have  both  abstract and concrete methods	interface can  have only abstract methods
4	A class can extend only one abstract class	A class can implement any number of interfaces
5	In abstract class keyword ‘abstract’ is mandatory to declare a method as an abstract	In an interface keyword ‘abstract’ is optional to declare a method as an abstract
6	abstract  class can have  protected , public and public abstract methods	Interface can have only public abstract methods i.e. by default
7	abstract class can have  static, final  or static final  variable with any access specifier	interface  can  have only static final (constant) variable i.e. by default