Difference Between Class and Interface

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Senior Executive - Content

Updated on Sep 18, 2023 11:03 IST

The main difference between class and interface is that a class describes the behavior of an object. In contrast, an interface contains the behaviors assigned and defined by the class.

This article will explain the difference between class and interface in great detail. Both classes and interfaces are used in order to lay the foundation of the Java programming language as they are related to the behaviors of the objects described in the content.

There are two smajor imilarities between class and interface and those similarities are:

They are both reference types.
Both are associated with Object-Oriented Programming.

Both class and interface also contains methods and variables, but even after so much, they differ in many ways. So, without further ado, let’s go over the topics listed in the table of contents we’ll cover in this article before delving deeper into the difference between class and interface.

Table of contents (TOC)

Difference between class and interface
What is a class?
Example of class
What is an interface?
Example of interface
Key differences between class and interface
Conclusion

Difference between class and interface

For better understanding, let’s explore the difference between class and interface in a tabular format:

Parameter	Class	Interface
Keyword used	Class	Interface
Objects can be created	Yes	No
It can inherit another class	Yes	No
It can be inherited by a class by using the keyword	Extends	Implements
Allows you to contain constructors	Yes	No
Allows you to contain abstract methods	No	Yes
Variables and methods can only be declared as public	No	Yes
Variables are	Static, final, or neither	Static
Supports multiple inheritance	No	Yes
Contains final and static methods	Yes	No

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Class definition: Class is a user-defined prototype required to create the object.

A class is a collection of properties or methods shared by all objects of the same type. The class declarations mention several components, such as:

Modifiers: A class can be either public or have default access.
Class name: The name of the class should begin with an initial letter.
Superclass: If applicable, the name of the class’s parent (superclass), preceded by the keyword, extends.
Interfaces: A comma-separated list of interfaces that the class, if any, implements, preceded by the keyword, implements.
Body: The class body is surrounded by curly brackets ({ }).

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Example of class

Here’s an example of a class named “Shikshaonline” with a variable x:

public class Shikshaonline { 
    int x = 5; 
  }
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Here’s an example of a class named “Shikshaonline” in which we are creating an object called “shikshaobj” and printing the value of x:

public class Shikshaonline { 
    int x = 5; 
    public static void main(String[] args) { 
        Shikshaonline shikshaObj = new Shikshaonline(); 
        System.out.println(shikshaObj.x); 
    } 
}
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What is an interface?

Interface definition: An interface is a class blueprint that includes static methods and variables.

In short, an interface is simply a collection of similar methods with empty bodies.

An interface is made up of a list of actions that an object can perform. For example, when you turn on a fan, all you have to do is flip the switch, and the fan starts; you don’t have to worry about how it works. The interface’s syntax is similar to that of the class. In the Java programming language, the interface is used to inherit more than one class at a time.

For more information, you can also explore: Interface in Java Explained

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Example of interface

Here’s an example of an interface:

// Interface
interface Animal {
  public void animalSound(); // interface method (does not have a body)
  public void sleep(); // interface method (does not have a body)
}

// Pig "implements" the Animal interface
class Pig implements Animal {
  public void animalSound() {
    // The body of animalSound() is provided here
    System.out.println("The pig says: wee wee");
  }
  public void sleep() {
    // The body of sleep() is provided here
    System.out.println("Zzz");
  }
}

class Main {
  public static void main(String[] args) {
    Pig myPig = new Pig();  // Create a Pig object
    myPig.animalSound();
    myPig.sleep();
  }
}
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Key differences between class and interface

Here are the key differences between class and interface:

Constructors can be included in a class but not an inheritance.
A method body can exist in a class, but it cannot exist in an interface.
Classes do not support multiple inheritance, but it is supported by inheritance.
To declare a class, you can use the keyword, class. However, in order to declare an interface, a keyword called interface is used.
A class’s members do not have to be made public. It can be public, private, or protected. Members of an interface, on the other hand, are always public.
A class may extend only one other class but as many interfaces as necessary. An interface, on the other hand, cannot implement interfaces but can extend any number of classes.

You can also explore: Difference between Abstract class and Interface in Java

Conclusion

The main distinction between a class and an interface is that a class will be used to describe the behavior of the objects in the program, whereas an interface will carry those behaviors. You will be able to code more efficiently now that you recognize the distinction between class and interface.

FAQs

What is the main difference between class and interface?

The main difference between class and interface is that a class will be used to describe the behavior of the objects in the program, whereas an interface will carry those behaviors.

In terms of the difference between class and interface, what is a class?

In regards to the difference between class and interface, a class is a user-defined prototype required in order to create the object.

In terms of the difference between class and interface, what is an interface?

In regards to the difference between class and interface, an interface is a class blueprint that includes static methods and variables.

In terms of the difference between class and interface, which of these two allows you to contain constructors?

In regards to the difference between class and interface, a class allows you to contain constructors.

In terms of the difference between class and interface, which of these two allows you to contain abstract methods?

In regards to the difference between class and interface, an interface allows you to contain abstract methods.

In terms of the difference between class and interface, which of these two supports multiple inheritance?

In regards to the difference between class and interface, an interface supports multiple inheritance.

About the Author

Anshuman Singh

Senior Executive - Content

Anshuman Singh is an accomplished content writer with over three years of experience specializing in cybersecurity, cloud computing, networking, and software testing. Known for his clear, concise, and informative wr... Read Full Bio

Difference Between Class and Interface

Difference between class and interface

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What is a class?