Car Rental System using Java

In this article I have created a simple Vehicle Rental System using Java. This code contains inheritance, object creation and method overriding.

EDIT: Code can be found at https://github.com/haarsh85/car-rental-system.git

Photo by Markus Spiske on Unsplash

Summary:

We have a class hierarchy with a base class called Vehicle and three subclasses: Car, Motorcycle, and Truck. Each vehicle type will have its unique attributes and methods. Additionally, we'll create a RentalSystem class to manage rental operations, allowing users to rent and return vehicles while calculating rental costs. Comments are added to respective line of codes for easy understanding.

Contents

1. Vehicle class:
   - Attributes: make, model, year, rentalRate
   - Methods: getMake(), getModel(), getRentalRate()
2. Subclasses (Car, Motorbike and Truck):
   - Inherited from the Vehicle class.
   - Has unique attributes and overridden the diaplayInfo() method.
3. RentalSystem class:
   - Maintains lists of available and rented vehicles.
   - Has methods to add vehicle, rent a vehicle, return a vehicle, display rental information.
   - Calculate total rental cost based on rental duration and vehicle’s rental rate.
4. RentalSystemDemo:
   - Has the main method.
   - Has user-friendly interface for renting, returning, and displaying vehicle information.

Implementation

Vehicle class (Super class)

public class Vehicle {
 private String make;
 private String model;
 private int year;
 private double rentalRate;
 
 public Vehicle(String make, String model, int year, double rentalRate) {
  this.make = make;
  this.model = model;
  this.year = year;
  this.rentalRate = rentalRate;
 }
 
 public void displayInfo() {
  System.out.println("Make: " + make);
  System.out.println("Model " + model);
  System.out.println("Year: " + year);
  System.out.println("Rental Rate: " + rentalRate);
 }
 
 public double getRentalRate() {
  return rentalRate;
 }
 
 public String getMake() {
  return make;
 }
 
 public String getModel() {
  return model;
 }
}

Subclasses (Car, Motorbike and Truck)
Car.java

public class Car extends Vehicle{
 
 private int numDoors;
 private boolean isConvertible;
 private String fuelType;
 
 public Car(String make, String model, int year, double rentalRate, int numDoors, boolean isConvertible, String fuelType) {
  super(make, model, year, rentalRate);
  this.numDoors = numDoors;
  this.isConvertible = isConvertible;
  this.fuelType = fuelType;
 }
 
 @Override
 public void displayInfo() {
  super.displayInfo();
  System.out.println("Number of Doors: " + numDoors);
  System.out.println("Convertible: " + isConvertible);
  System.out.println("Fuel Type: " + fuelType);
 }

}

Motorbike.java

public class Motorbike extends Vehicle{
 
 private String bikeType;
 
 public Motorbike(String make, String model, int year, double rentalRate, String bikeType) {
  super(make, model, year, rentalRate);
  this.bikeType = bikeType;
 }
 
 @Override
 public void displayInfo() {
  super.displayInfo();
  System.out.println("Bike Type" + bikeType);
 }

}

Truck.java

public class Truck extends Vehicle{
 
 private int loadCapacity;
 private boolean isFourWheelDrive;
 private String cargoType;
 
 public Truck(String make, String model, int year, double rentalRate, int loadCapacity, boolean isFourWheelDrive, String cargoType) {
  super(make, model, year, rentalRate);
  this.loadCapacity = loadCapacity;
  this.isFourWheelDrive = isFourWheelDrive;
  this.cargoType = cargoType;
 }
 
 @Override
 public void displayInfo() {
  super.displayInfo();
  System.out.println("Load Capacity: " + loadCapacity);
  System.out.println("Four wheel drive: " + isFourWheelDrive);
  System.out.println("Cargo type: " + cargoType);
  
 }

}

RentalSystem class

import java.util.ArrayList;
import java.util.List;

public class RentalSystem {
 
 private List<Vehicle> availableVehicles;
 private List<Vehicle> rentedVehicles;
 
 public RentalSystem() {
  availableVehicles = new ArrayList<>();
  rentedVehicles = new ArrayList<>();
 }
 
 //to add vehicles to rental system
 public void addVehicle(Vehicle vehicle) {
  availableVehicles.add(vehicle);
 }
 
 public List<Vehicle> getAvailableVehicles(){
  return availableVehicles;
 }
 
 public List<Vehicle> getRentedVehicles(){
  return rentedVehicles;
 }
 
 //to rent vehicle
 public void rentVehicle(Vehicle vehicle) {
  if(availableVehicles.contains(vehicle)) {
   availableVehicles.remove(vehicle);
   rentedVehicles.add(vehicle);
  }
 }
 
 //to return rented vehicle
 public void returnVehicle(Vehicle vehicle) {
  if(rentedVehicles.contains(vehicle)) {
   rentedVehicles.remove(vehicle);
   availableVehicles.add(vehicle);
  }
 }
 
 //To display available and rented vehicles
 public void displayRentalInfo() {
  System.out.println("Available vehicles: ");
  for(Vehicle av : availableVehicles) {
   av.displayInfo();
   System.out.println();
  }
  
  System.out.println("Rented vehicles: ");
  for(Vehicle rv : rentedVehicles) {
   rv.displayInfo();
   System.out.println();
  }
 }
 
 //To calculate total rental cost
 public double calculateRentalCost(Vehicle vehicle, int rentalDuration) {
  double rentalRate = vehicle.getRentalRate();
  double totalCost = rentalRate * rentalDuration;
  return totalCost;
 }

}

Main Application (RentalSystemDemo.java)

import java.util.Scanner;

public class Test1Demo {
 
 public static void main(String[] args) {
  
  //Creating scanner object to get user input
  Scanner scanner = new Scanner(System.in);
  //Creating RentalSystem object which is used to call the respective methods
  RentalSystem rentalSystem = new RentalSystem();
  
  Vehicle car = new Vehicle("Toyota", "Supra", 2020, 100);
  Vehicle motorbike = new Vehicle("Honda", "CXR", 2000, 50);
  Vehicle truck = new Vehicle("Ford", "F150", 2001, 200);
  
  rentalSystem.addVehicle(car);
  rentalSystem.addVehicle(motorbike);
  rentalSystem.addVehicle(truck);
  
  while (true) {
   //Options for the user
   System.out.println();
   System.out.println("===== Vehicle Rental System =====");
   System.out.println("1. Rent a Vehicle");
   System.out.println("2. Return a Vehicle");
   System.out.println("3. Display Rental Information");
   System.out.println("4. Exit");
   System.out.println();
   System.out.print("Enter your choice: ");
   
   int choice = scanner.nextInt();
   scanner.nextLine();
   
   switch (choice) {
   case 1: {
    //Rent a vehicle
    System.out.print("Enter the vehicle make: ");
    String make = scanner.nextLine();
    System.out.print("Enter the vehicle model: ");
    String model = scanner.nextLine();
    
    Vehicle selectedVehicle = null;
    
    //Checks the vehicles in available vehicles
    for(Vehicle v : rentalSystem.getAvailableVehicles()) {
     if(v.getMake().equalsIgnoreCase(make) && v.getModel().equalsIgnoreCase(model)) {
      selectedVehicle = v;
     }
     
    }
    
    if(selectedVehicle != null) {
     //Add the vehicle to rented vehicles
     rentalSystem.rentVehicle(selectedVehicle);
     System.out.print("Enter the rental duration in days: ");
     int rentalDuration = scanner.nextInt();
     //Calculate total rental cost
     double rc = rentalSystem.calculateRentalCost(selectedVehicle, rentalDuration);
     System.out.println("Successfully rented.");
     System.out.println("Total rental Cost: " + rc);
    }
    else {
     System.out.println("Matching vehicle is not available for rent.");
    }
    break;

   }
   
   case 2: {
    //Return a vehicle
    System.out.println("Enter the vehicle make: ");
    String make = scanner.nextLine();
    System.out.println("Enter the vehicle model: ");
    String model = scanner.nextLine();
    
    Vehicle selectedVehicle = null;
    
    //Checks the vehicles in rented vehicles
    for(Vehicle v : rentalSystem.getRentedVehicles()) {
     if(v.getMake().equalsIgnoreCase(make) && v.getModel().equalsIgnoreCase(model)) {
      selectedVehicle = v;
     }
    }
    if(selectedVehicle != null) {
     //Add to the returned vehicles
     rentalSystem.returnVehicle(selectedVehicle);
     System.out.println("Vehicle returned successfully.");
    }
    else {
     System.out.println("Invalid return. Vehicle not rented.");
    }
   }
   
   case 3: {
    //Display Rental Information
    rentalSystem.displayRentalInfo();  
    break;
   }
   
   case 4: {
    //Exit
     System.out.println("Thank you for using the Vehicle Rental System. Goodbye!");
     scanner.close();
     System.exit(0);
   }
   
   default:
    System.out.println("Invalid choice. Please enter valid option...");

   }
  }

 }

}

Output

Option 1: Rent a Vehicle
Rented vehicle Toyota.

===== Vehicle Rental System =====
1. Rent a Vehicle
2. Return a Vehicle
3. Display Rental Information
4. Exit

Enter your choice: 1
Enter the vehicle make: toyota
Enter the vehicle model: supra
Enter the rental duration in days: 15
Successfully rented.
Total rental Cost: 1500.0

===== Vehicle Rental System =====
1. Rent a Vehicle
2. Return a Vehicle
3. Display Rental Information
4. Exit

Enter your choice: 

Option 3: Display Rental Information
Toyota is now added under Rented Vehicles.

Enter your choice: 3
Available vehicles: 
Make: Honda
Model CXR
Year: 2000
Rental Rate: 50.0

Make: Ford
Model F150
Year: 2001
Rental Rate: 200.0

Rented vehicles: 
Make: Toyota
Model Supra
Year: 2020
Rental Rate: 100.0


===== Vehicle Rental System =====
1. Rent a Vehicle
2. Return a Vehicle
3. Display Rental Information
4. Exit

Enter your choice: 

Option 2: Return a Vehicle
Toyota is returned successfully and all available vehicles are returned.

Enter your choice: 2
Enter the vehicle make: 
toyota
Enter the vehicle model: 
supra
Vehicle returned successfully.
Available vehicles: 
Make: Honda
Model CXR
Year: 2000
Rental Rate: 50.0

Make: Ford
Model F150
Year: 2001
Rental Rate: 200.0

Make: Toyota
Model Supra
Year: 2020
Rental Rate: 100.0

Rented vehicles: 

===== Vehicle Rental System =====
1. Rent a Vehicle
2. Return a Vehicle
3. Display Rental Information
4. Exit

Enter your choice: 

In conclusion, I hope this article will help to understand inheritance with a practical scenario. Happy coding :)

Thank you for reading and stay safe!