Difference between abstract class and interface

Abstract class and interface both are used to achieve abstraction where we can declare the abstract methods. Abstract class and interface both can't be instantiated.

But there are many differences between abstract class and interface that are given below.

Abstract class	Interface
1) Abstract class can have abstract and non-abstract methods.	Interface can have only abstract methods. Since Java 8, it can have default and static methods also.
2) Abstract class doesn't support multiple inheritance.	Interface supports multiple inheritance.
3) Abstract class can have final, non-final, static and non-static variables.	Interface has only static and final variables.
4) Abstract class can provide the implementation of interface.	Interface can't provide the implementation of abstract class.
5) The abstract keyword is used to declare abstract class.	The interface keyword is used to declare interface.
6) An abstract class can extend another Java class and implement multiple Java interfaces.	An interface can extend another Java interface only.
7) An abstract class can be extended using keyword "extends".	An interface can be implemented using keyword "implements".
8) A Java abstract class can have class members like private, protected, etc.	Members of a Java interface are public by default.
9)Example: public abstract class Shape{ public abstract void draw(); }	Example: public interface Drawable{ void draw(); }

Simply, abstract class achieves partial abstraction (0 to 100%) whereas interface achieves fully abstraction (100%).

Example of abstract class and interface in Java

Let's see a simple example where we are using interface and abstract class both.

//Creating interface that has 4 methods
interface A{
void a();//bydefault, public and abstract
void b();
void c();
void d();
}

//Creating abstract class that provides the implementation of one method of A interface
abstract class B implements A{
public void c(){System.out.println("I am C");}
}

//Creating subclass of abstract class, now we need to provide the implementation of rest of the methods
class M extends B{
public void a(){System.out.println("I am a");}
public void b(){System.out.println("I am b");}
public void d(){System.out.println("I am d");}
}

//Creating a test class that calls the methods of A interface
class Test5{
public static void main(String args[]){
A a=new M();
a.a();
a.b();
a.c();
a.d();
}}

Test it Now

Output:

       I am a
       I am b
       I am c
       I am d

Next TopicPackage in Java

← prev next →

Latest Courses

We provides tutorials and interview questions of all technology like java tutorial, android, java frameworks

Contact info

G-13, 2nd Floor, Sec-3, Noida, UP, 201301, India

[email protected].

Python

AI, ML and Data Science

Java

B.Tech and MCA

Web Technology

Software Testing

Technical Interview

Java Interview

Web Interview

Database Interview

Company Interviews

Java Tutorial

Control Statements

Java Object Class

Java Inheritance

Java Polymorphism

Java Abstraction

Java Encapsulation

Java Array

Java OOPs Misc

Java String

Java String Methods

Java Regex

Exception Handling

Java Inner Class

Java Multithreading

Java Synchronization

Java Networking

Java Applet

Java Reflection

Java Conversion

Java JDBC

RMI

Internationalization

Java Array Class

Java AtomicInteger Class

Java AtomicLong Methods

Java Authenticator

Java BigDecimal class

Big Integer Class

Java Boolean class

Java Byte Class

Java Class

Java Collections class

Java Compiler Class

CopyOnWriteArrayList

Java Math Methods

LinkedBlockingDeque

Java Long class

LinkedTransferQueue

Java List

Java MulticastSocket

Java Number Class

Java Phaser Class

ArrayList Methods

Java Thread Methods

Java Projects

Java Programs

Java Misc

Java Date Class

Java ListIterator Class

Java NIO Tutorial

HttpURLConnection

Java Deque

Java HttpCookie Class

Java URL class

Java List Methods

Java Vector class

Java Collection Methods

Java Socket Class

Java Executors

Java ConcurrentHashMap

Java ConcurrentLinkedQueue

Difference between abstract class and interface

Example of abstract class and interface in Java

Latest Courses

Contact info

Follow us

Tutorials

Interview Questions