Java Class and Objects

In Java, everything revolves around classes and objects. A class is a blueprint for creating objects, while an object is an instance of a class. Understanding these fundamental concepts is crucial for working with Object-Oriented Programming (OOP) in Java.

What is a Class?#

A class is a template or blueprint that defines the attributes (fields) and behaviors (methods) of objects. It acts as a structure for creating multiple objects with similar properties.

Example:#

Think of a car manufacturing company. Before making cars, the company designs a blueprint with specifications like color, engine type, and speed. This blueprint is like a class in Java.

In Java, a class is declared using the class keyword:

// Defining a class named Car
class Car {
    // Attributes (fields)
    String brand;
    int speed;

    // Method to display car details
    void displayCar() {
        System.out.println("Brand: " + brand);
        System.out.println("Speed: " + speed + " km/h");
    }
}

What is an Object?#

An object is an instance of a class. When a class is defined, no memory is allocated until an object is created.

Example:#

A real-world car (like a Tesla or BMW) is an object created from the blueprint (class). Each car object has its own unique attributes (color, model, speed).

In Java, we create an object using the new keyword:

// Creating an object of the Car class
public class Main {
    public static void main(String[] args) {
        // Creating an object
        Car myCar = new Car();

        // Assigning values to object properties
        myCar.brand = "Tesla";
        myCar.speed = 200;

        // Calling the method
        myCar.displayCar();
    }
}

Output:#

Brand: Tesla
Speed: 200 km/h

Key Characteristics of Classes and Objects#

• A class is a template, while an object is a real-world entity created from that template.
• Multiple objects can be created from a single class.
• Objects have attributes (variables) and behaviors (methods).

Conclusion#

Understanding classes and objects is the foundation of Java programming. A class defines the structure, while objects are actual instances that store data and perform actions. This concept helps in writing modular, reusable, and efficient code.