by Jasleen Chhabra | Updated on 24 August 2024

Table of Contents (Click any Topic to view first)

1.  Classes in Java
2. Objects in Java
3. Example: Creating a Class and Object in Java
4. Key Concepts

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Understanding the Classes and Objects (OOP's Concepts) in Java

In Java programming, objects and classes form the backbone of object-oriented programming (OOP) principles. They enable developers to model real-world entities and encapsulate their behavior and state. Let's explore objects and classes in Java in detail, along with examples to illustrate their usage.

Classes in Java:

• Definition: A class in Java is a blueprint or template that defines the structure and behavior of objects. It encapsulates data (attributes) and methods (functions) to operate on that data.
• Syntax:

public class ClassName {

    // Data members (fields)

    // Constructor(s)

    // Methods

}

Objects in Java:

• Definition: An object is an instance of a class. It represents a specific entity with its unique state (attributes) and behavior (methods).
• Syntax:

ClassName objectName = new ClassName();

Example: Creating a Class and Object in Java:

// Class definition

public class Car {

    // Data members

    String brand;

    String model;

    int year;

    // Constructor

    public Car(String brand, String model, int year) {

        this.brand = brand;

        this.model = model;

        this.year = year;

    }

    // Method to display car details

    public void displayDetails() {

        System.out.println("Brand: " + brand);

        System.out.println("Model: " + model);

        System.out.println("Year: " + year);

    }

}

 

// Main class

public class Main {

    public static void main(String[] args) {

        // Creating an object of the Car class

        Car myCar = new Car("Toyota", "Camry", 2021);

       

        // Accessing object's methods

        myCar.displayDetails();

    }

}

In this example:

• We define a Car class with data members brand, model, and year, along with a constructor to initialize these attributes.
• We create an object myCar of the Car class using the new keyword.
• We access the displayDetails() method of the myCar object to print its details.

Key Concepts:

1. Class: Defines the blueprint or template for objects.
2. Object: Represents a specific instance of a class with its unique state and behavior.
3. Encapsulation: Bundles data and methods within a class, hiding the internal implementation details.
4. Constructor: Initializes the state of an object when it is created.
5. Method: Defines behaviors or actions that objects can perform.

Conclusion:

Understanding objects and classes is fundamental in Java programming. By defining classes and creating objects, developers can model complex systems, organize code logically, and build scalable and maintainable applications.

 

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