---
title: "What is similarities/difference between an Abstract class and Interface?"  
description: "What is similarities/difference between an Abstract class and Interface?"  
author: "Rajesh Goswami"  
published: 2011-01-19  
updated: 2020-09-22  
canonical: https://www.mindstick.com/interview/331/what-is-similarities-difference-between-an-abstract-class-and-interface  
category: "java"  
tags: ["java"]  
reading_time: 2 minutes  

---

# What is similarities/difference between an Abstract class and Interface?

**Difference between an Abstract class and Interface**\
Interfaces provide a form of multiple inheritance. A class can extend only one other class.

- Interfaces are limited to public methods and constants with no implementation. Abstract classes can have a partial implementation, protected parts, static methods, etc.
- A Class may implement several interfaces. But in case of abstract class, a class may extend only one abstract class.
- Interfaces are slow as it requires extra indirection to to find corresponding method in in the actual class. Abstract classes are fast.

## Similarities:

- Neither Abstract classes or Interface can be instantiated.\

## Answers

### Answer by Rajesh Goswami

**Difference between an Abstract class and Interface**\
Interfaces provide a form of multiple inheritance. A class can extend only one other class.

- Interfaces are limited to public methods and constants with no implementation. Abstract classes can have a partial implementation, protected parts, static methods, etc.
- A Class may implement several interfaces. But in case of abstract class, a class may extend only one abstract class.
- Interfaces are slow as it requires extra indirection to to find corresponding method in in the actual class. Abstract classes are fast.

## Similarities:

- Neither Abstract classes or Interface can be instantiated.\


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