OOP project sample 2024-25

main.dart

import 'dart:io';

// Base Vehicle class (demonstrates abstraction and inheritance)
abstract class Vehicle {
  // Properties (demonstrates encapsulation with private fields)
  String _make;
  String _model;
  int _year;
  
  // Constructor
  Vehicle(this._make, this._model, this._year);
  
  // Getters
  String get make => _make;
  String get model => _model;
  int get year => _year;
  
  // Abstract method (for polymorphism)
  String getVehicleType();
  
  // Common method
  String getDetails() {
    return '$_year $_make $_model (${getVehicleType()})';
  }
}

// Car class extending Vehicle (demonstrates inheritance)
class Car extends Vehicle {
  int _doors;
  
  Car(String make, String model, int year, this._doors) 
      : super(make, model, year);
  
  @override
  String getVehicleType() {
    return 'Car';
  }
  
  @override
  String getDetails() {
    return '${super.getDetails()}, $_doors doors';
  }
}

// Motorcycle class extending Vehicle (demonstrates polymorphism)
class Motorcycle extends Vehicle {
  Motorcycle(String make, String model, int year) 
      : super(make, model, year);
  
  @override
  String getVehicleType() {
    return 'Motorcycle';
  }
}

// Main program
void main() {
  // Create a list of vehicles (demonstrates polymorphism)
  List<Vehicle> vehicles = [
    Car("Toyota", "Corolla", 2020, 4),
    Car("Honda", "Civic", 2019, 2),
    Motorcycle("Yamaha", "R1", 2021)
  ];
  
  bool running = true;
  while (running) {
    printMenu();
    print('Enter your choice: ');
    String? choice = stdin.readLineSync();
    
    switch(choice) {
      case '1':
        addVehicle(vehicles);
        break;
      case '2':
        removeVehicle(vehicles);
        break;
      case '3':
        searchVehicle(vehicles);
        break;
      case '4':
        showAllVehicles(vehicles);
        break;
      case 'q':
        running = false;
        print('Goodbye!');
        break;
      default:
        print('Invalid choice. Please try again.');
    }
  }
}

// Menu display function
void printMenu() {
  print('\n===== Vehicle Management System =====');
  print('1. Add a vehicle');
  print('2. Remove a vehicle');
  print('3. Search for a vehicle');
  print('4. Show all vehicles');
  print('q. Quit');
  print('====================================');
}

// Add vehicle function
void addVehicle(List<Vehicle> vehicles) {
  print('\nAdd a new vehicle:');
  print('What type of vehicle? (1 for Car, 2 for Motorcycle): ');
  String? typeChoice = stdin.readLineSync();
  
  print('Enter make: ');
  String? make = stdin.readLineSync();
  
  print('Enter model: ');
  String? model = stdin.readLineSync();
  
  print('Enter year: ');
  String? yearStr = stdin.readLineSync();
  
  // Basic validation
  if (make == null || model == null || yearStr == null) {
    print('Invalid input. Please try again.');
    return;
  }
  
  int? year;
  try {
    year = int.parse(yearStr);
  } catch (e) {
    print('Invalid year. Please enter a number.');
    return;
  }
  
  if (typeChoice == '1') {
    print('Enter number of doors: ');
    String? doorsStr = stdin.readLineSync();
    
    int? doors;
    try {
      doors = int.parse(doorsStr ?? '0');
    } catch (e) {
      print('Invalid number of doors. Using 4 as default.');
      doors = 4;
    }
    
    vehicles.add(Car(make, model, year, doors));
    print('Car added successfully!');
  } 
  else if (typeChoice == '2') {
    vehicles.add(Motorcycle(make, model, year));
    print('Motorcycle added successfully!');
  }
  else {
    print('Invalid vehicle type.');
  }
}

// Remove vehicle function
void removeVehicle(List<Vehicle> vehicles) {
  if (vehicles.isEmpty) {
    print('No vehicles to remove.');
    return;
  }
  
  print('\nRemove a vehicle:');
  showAllVehicles(vehicles);
  
  print('Enter the number of the vehicle to remove: ');
  String? indexStr = stdin.readLineSync();
  
  try {
    int index = int.parse(indexStr ?? '0') - 1;
    if (index >= 0 && index < vehicles.length) {
      Vehicle removed = vehicles.removeAt(index);
      print('Removed: ${removed.getDetails()}');
    } else {
      print('Invalid vehicle number.');
    }
  } catch (e) {
    print('Please enter a valid number.');
  }
}

// Search vehicle function
void searchVehicle(List<Vehicle> vehicles) {
  print('\nSearch for a vehicle:');
  print('Enter make to search for: ');
  String? searchMake = stdin.readLineSync();
  
  if (searchMake == null || searchMake.isEmpty) {
    print('Invalid search term.');
    return;
  }
  
  bool found = false;
  for (var vehicle in vehicles) {
    if (vehicle.make.toLowerCase() == searchMake.toLowerCase()) {
      print('Found: ${vehicle.getDetails()}');
      found = true;
    }
  }
  
  if (!found) {
    print('No vehicles found with make: $searchMake');
  }
}

// Show all vehicles function
void showAllVehicles(List<Vehicle> vehicles) {
  if (vehicles.isEmpty) {
    print('No vehicles to display.');
    return;
  }
  
  print('\nAll Vehicles:');
  for (int i = 0; i < vehicles.length; i++) {
    print('${i+1}. ${vehicles[i].getDetails()}');
  }
}