Difference between abstract class and interface

Answer Posted / cheshta

1. Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior.
2. Variables declared in a Java interface is by default final. An abstract class may contain non-final variables.
Members of a Java interface are public by default. A Java abstract class can have the usual flavors of class members like private, protected, etc..
3. Java interface should be implemented using keyword “implements”; A Java abstract class should be extended using keyword “extends”.
4. An interface can extend another Java interface only, an abstract class can extend another Java class and implement multiple Java interfaces.
5. A Java class can implement multiple interfaces but it can extend only one abstract class.
Interface is absolutely abstract and cannot be instantiated; 6. A Java abstract class also cannot be instantiated, but can be invoked if a main() exists.
7. In comparison with java abstract classes, java interfaces are slow as it requires extra indirection.

Is This Answer Correct ?    0 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

What are the types of memory management? : Dot net architecture

666


What is the purpose of cache? : Dot net architecture

726


Define pipelining? : Dot net architecture

793


Is .net easier than java?

687


What is the difference between an event and a delegate?

723


What are the different pipelining hazards? : Dot net architecture

790


How do I stop a thread?

717


Session State and can i store desirialized object in state server, if yes how and if not why.

1527


What is the access level of the visibility type internal?

764


Explain element .net mobile with example? : Microsoft dot net mobile

733


What is the difference between metadata and menifest ?

655


How to develop mobile applications using microsoft mobile internet toolkit (mmit) or .net mobile? : Microsoft dot net mobile

696


Can you Explain element .net mobile with example? : Microsoft dot net mobile

683


Does application frame need host?

717


What are different types that a variable can be defined and their scopes ?

819