Difference Between Abstract Class and Interface

Java is one of the most widely used programming languages among programmers. Despite its age and the introduction of Python as an alternative, Java's reliability and popularity ensure that it will continue to be used in development for many years to come.

Programmers and developers who wish to fully use Java's capabilities should improve their knowledge of the language and its capabilities. This newfound knowledge fits very perfectly with the notion of upskilling. To that purpose, we'll go through Java abstraction methods in this lecture. This article will explain the distinctions between abstract classes and Java interfaces, two of the Java programming language's basic building components.

Let's start with some definitions before we go into the abstract class versus interface java discussion.

What is an Abstraction?

Abstraction is defined in the IT industry as the process of masking internal implementation details and only displaying important functionality to the user. To put it another way, you don't need to understand how sausages are created before you eat one. All you need to know are the procedures to properly prepare it. It makes no difference how it ended up on your plate.

To put it another way, since the abstraction process is centered on a vehicle, you can see and interact with the steering wheel as well as the gas and brake pedals. The fuel injection system and the serpentine belt are not accessible.

What is an Abstract Class?

An abstract class is one that has the "abstract" keyword in its declaration. It's a set of common subclass traits with at least one abstract method. There may be several concrete methods in an abstract class. Java 8 and subsequent programmers may use default and static methods as well.

You can't create an object with an abstract class because it can't be instantiated.

Abstract class vs interface Java is used by programmers when they need to:

• Subclasses' default functionality
• Templates for individual classes in the future
• Creating a standard interface for all subclasses
• Reusability of code

Before we go into the differences between abstract classes and interfaces in Java, let's have a look at what an interface is in Java.

What is an Interface?

A blueprint for implementing a class is called an interface. Unlike abstract classes, it is a collection of abstract methods with no real methods. The interface, on the other hand, provides complete abstraction in Java, whereas abstract classes cannot.

An interface, like a class, may include methods and variables, however, the specified methods are abstract by default.

Abstract classes that implement interfaces can be instantiated, but interfaces themselves cannot.

When you're in one of the following situations, you should utilize an interface:

You wish to implement your interface using unrelated classes. The Comparable and Clonable interfaces, for example, are implemented by unrelated classes.
You wish to impose a set of controlled operations in a data type, such as adding the meaning of comparison to the implementation of a Comparable interface through the compareTo method.
You want to imitate several inheritances, for example, if you want your user-defined class to be comparable and clonable, you may list the interfaces that describe these constructions, or if you need to share API contracts.

The interface is used by programmers when they need to:

• Aiming towards abstraction
• To allow for dynamic resolution at runtime
• Obtaining a loose coupling
• separating the definition of a method from the hierarchy of inheritance

Let's look at the main distinctions between an abstract class and an interface now.

Comparison Table Between Abstract Class and Interface