OOP Overview

• Object-Oriented Programming (or OOP) is a JAVA paradigm that organizes software design around data, or objects rather than functions and logic.

Classes:

To create an object a Class is required.

• A class is a blueprint for creating objects. It defines the properties and behaviors that objects of a certain class can have.
• Classes specify what data an object can have (attributes) and what it can do (methods).
• A class bundles its attributes and methods through encapsulation (1. Encapsulation), protecting the data.

public class Car {
    // Fields, attributes, data variables - represent the data associated with a class. They define the state of an object.
    String color;
    String model;
    int year;
 
    // Methods, functions, data methods - define the behavior of a class. 
    // They operate on the fields of the class and perform actions or computations.
    void displayDetails() {
        System.out.println("Model: " + model + ", Color: " + color + ", Year: " + year);
    }
}

Objects:

Objects are any real world entity (like car, bike, dog, ATM, etc.) which has two things:

• Properties or State
• Behavior or Function

Example

Dog is an object:

• Properties like: Age, Breed, Color, etc.
• Behaviors like: Bark, Sleep, Eat, etc.

An object is an instance of a class. Each object has its own set of fields defined by the class, but the methods are shared among all objects of the class.

Creating Objects

public class Main {
    public static void main(String[] args) {
        Car car1 = new Car(); // Creating an object of the Car class
        car1.color = "Red";   // Setting fields
        car1.model = "Toyota";
        car1.year = 2020;
 
        car1.displayDetails(); // Calling a method on the object
    }
}