What is object-oriented programming (OOP) in Java?

Object-oriented programming in Java is a paradigm based on the concept of "objects" that contain data (properties) and methods (actions).

Main principles of OOP in Java:

1. Encapsulation: Hiding data and methods inside an object, access only through defined interfaces. Ensures data security and modularity.
2. Inheritance: Allows creating new classes (subclasses) based on existing ones (superclasses), inheriting their properties and methods. Promotes code reuse.
3. Polymorphism: Enables using objects of different classes through a common interface. Provides flexibility and extensibility. Includes compile-time (overloading) and runtime (overriding) polymorphism.
4. Abstraction: Highlighting essential characteristics and hiding non-essential details. Simplifies complex systems.

Example of a class in Java:

public class Car {
    private String brand; // Encapsulated property
    private String model;
    private int year;

    public Car(String brand, String model, int year) { // Constructor
        this.brand = brand;
        this.model = model;
        this.year = year;
    }

    public void displayInfo() { // Method
        System.out.println("Brand: " + brand + ", Model: " + model + ", Year: " + year);
    }

    // Getters and setters
    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }
}

Example of using OOP principles:

// Inheritance
public class ElectricCar extends Car {
    private int batteryCapacity;

    public ElectricCar(String brand, String model, int year, int batteryCapacity) {
        super(brand, model, year); // Call parent constructor
        this.batteryCapacity = batteryCapacity;
    }

    @Override // Polymorphism (method overriding)
    public void displayInfo() {
        super.displayInfo(); // Call parent method
        System.out.println("Battery Capacity: " + batteryCapacity + " kWh");
    }
}

// Using objects
public class Main {
    public static void main(String[] args) {
        Car myCar = new Car("Toyota", "Camry", 2020);
        Car myElectricCar = new ElectricCar("Tesla", "Model 3", 2022, 75);

        myCar.displayInfo();
        myElectricCar.displayInfo(); // Polymorphism in action
    }
}

Advantages of OOP:

• Code reuse: Through inheritance.
• Ease of maintenance: Changes affect only specific objects or classes.
• Flexibility and extensibility: Thanks to polymorphism.
• Improved code organization: Dividing system into modules (objects).
• Data security: Through encapsulation.