VehicleInheritanceDemo.java

import java.util.Scanner;

// 1. Base Class
class Vehicle {
    protected String regNumber;
    protected int speed;
    protected String color;
    protected String ownerName;

    // Constructor to initialize base fields
    public Vehicle(String regNumber, int speed, String color, String ownerName) {
        this.regNumber = regNumber;
        this.speed = speed;
        this.color = color;
        this.ownerName = ownerName;
    }

    public void showData() {
        System.out.println("\n--- This is Vehicle class ---");
    }
}

// 2. Derived Class: Bus
class Bus extends Vehicle {
    private int routeNumber;

    public Bus(String regNumber, int speed, String color, String ownerName, int routeNumber) {
        // Calling the parent class constructor using 'super'
        super(regNumber, speed, color, ownerName);
        this.routeNumber = routeNumber;
    }

    // Overriding the base method
    @Override
    public void showData() {
        super.showData(); // Invoke parent method
        System.out.println("Bus Details:");
        System.out.println("Registration Number: " + this.regNumber);
        System.out.println("Speed: " + this.speed + " km/h");
        System.out.println("Color: " + this.color);
        System.out.println("Owner Name: " + this.ownerName);
        System.out.println("Route Number: " + this.routeNumber);
    }
}

// 3. Derived Class: Car
class Car extends Vehicle {
    private String manufacturerName;

    public Car(String regNumber, int speed, String color, String ownerName, String manufacturerName) {
        // Calling the parent class constructor using 'super'
        super(regNumber, speed, color, ownerName);
        this.manufacturerName = manufacturerName;
    }

    // Overriding the base method
    @Override
    public void showData() {
        super.showData(); // Invoke parent method
        System.out.println("Car Details:");
        System.out.println("Registration Number: " + this.regNumber);
        System.out.println("Speed: " + this.speed + " km/h");
        System.out.println("Color: " + this.color);
        System.out.println("Owner Name: " + this.ownerName);
        System.out.println("Manufacturer: " + this.manufacturerName);
    }
}

// 4. Main Driver Class (PascalCase)
public class VehicleInheritanceDemo {
    public static void main(String[] args) {
        // Using a single Scanner for better resource management
        Scanner scanner = new Scanner(System.in);

        // --- Bus Input ---
        System.out.println("--- Enter Bus Details ---");
        System.out.print("Enter Registration Number: ");
        String busReg = scanner.nextLine();
        
        System.out.print("Enter Speed: ");
        int busSpeed = getValidInt(scanner);
        scanner.nextLine(); // Consume leftover newline
        
        System.out.print("Enter Color: ");
        String busColor = scanner.nextLine();
        
        System.out.print("Enter Owner Name: ");
        String busOwner = scanner.nextLine();
        
        System.out.print("Enter Route Number: ");
        int busRoute = getValidInt(scanner);
        scanner.nextLine(); // Consume leftover newline

        // Instantiate Bus object
        Bus bus = new Bus(busReg, busSpeed, busColor, busOwner, busRoute);

        // --- Car Input ---
        System.out.println("\n--- Enter Car Details ---");
        System.out.print("Enter Registration Number: ");
        String carReg = scanner.nextLine();
        
        System.out.print("Enter Speed: ");
        int carSpeed = getValidInt(scanner);
        scanner.nextLine(); // Consume leftover newline
        
        System.out.print("Enter Color: ");
        String carColor = scanner.nextLine();
        
        System.out.print("Enter Owner Name: ");
        String carOwner = scanner.nextLine();
        
        System.out.print("Enter Manufacturer Name: ");
        String carManuf = scanner.nextLine();

        // Instantiate Car object
        Car car = new Car(carReg, carSpeed, carColor, carOwner, carManuf);

        // --- Display Output ---
        System.out.println("\n=============================");
        System.out.println("       VEHICLE RECORDS       ");
        System.out.println("=============================");
        bus.showData();
        System.out.println("-----------------------------");
        car.showData();

        scanner.close();
    }

    // Helper Method to prevent Scanner crashes during numeric input
    private static int getValidInt(Scanner scanner) {
        while (!scanner.hasNextInt()) {
            System.out.print("Invalid input. Please enter a valid number: ");
            scanner.next(); // Consume invalid input
        }
        return scanner.nextInt();
    }
}