Difference Between Class and Object in Java

7/23/2025
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Difference Between Class Object in Java

Difference Between Class and Object in Java

Difference Between Class and Object in Java

Introduction

In Java and other object-oriented programming languages, classes and objects are the foundational building blocks. Understanding the difference between a class and an object is essential for writing efficient and maintainable code.

In this article, we’ll cover:

  • What is a class?

  • What is an object?

  • Key differences between class and object

  • Real-world examples

  • Code snippets

 What is a Class in Java?

A class is a blueprint or template for creating objects. It defines variables (fields) and methods (functions) that describe the behavior and properties of an object.

Syntax Example:

class Car {
    String model;
    int year;

    void drive() {
        System.out.println("Car is driving");
    }
}

Here, Car is a class that defines what a car has and does.

What is an Object in Java?

An object is an instance of a class. When a class is instantiated using the new keyword, it becomes an object.

Object Example:

public class Main {
    public static void main(String[] args) {
        Car myCar = new Car(); // Object creation
        myCar.model = "Toyota";
        myCar.year = 2020;
        myCar.drive();
    }
}

Here, myCar is an object of the Car class.

Difference Between Class and Object

Feature Class Object
Definition Blueprint/template for objects Instance of a class
Memory Allocation No memory is allocated Memory is allocated during creation
Declaration Keyword Declared using class Created using new keyword
Purpose Defines structure and behavior Performs actions and holds data
Example class Car {} Car myCar = new Car();

Real-Life Analogy

Think of a class as an architectural blueprint of a house.

  • The blueprint itself is not a house.

  • But using the blueprint, you can build multiple objects (houses).

So:

  • Class = Blueprint

  • Object = Actual house built from blueprint

Key Points

  • You can create multiple objects from a single class.

  • Changes in one object do not affect others.

  • A class defines what an object should be.

FAQs

Q1: Can we create an object without a class?
No. Every object in Java must be created from a class.

Q2: Can we define a method in an object directly?
No. Methods are defined in a class, and called through objects.

Q3: Are class and object both mandatory in Java?
Yes. Java is a purely object-oriented language. You need both.

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