Factory Method with C# code example

Definition

The factory method pattern defines an interface for creating an object, but let subclasses decides which class to instantiate.

The Class digram

The implementation

• Vehicle Factory :- Abstract Factory

public abstract class VehicleFactory
{
    public enum VehicleType
    {
        Car,
        Bicycle
    }

    public abstract Vehicle CreateVehicle(VehicleType vehicleType);

    public Vehicle OrderVehicle(VehicleType vehicleType)
    {
        Console.WriteLine("You are Ordering a " + vehicleType);
        return CreateVehicle(vehicleType);
    }
 }

• Bicycle, Car Factory :- Concrete Factory




public class BicycleFactory : VehicleFactory
{
    public override Vehicle CreateVehicle(VehicleType vehicleType)
    {
        Console.WriteLine("Creating a " + vehicleType);
        return new MotorBicycle();
    }
}





public class CarFactory : VehicleFactory
{
    public override Vehicle CreateVehicle(VehicleType vehicleType)
    {
        Console.WriteLine("Creating a " + vehicleType);
        return new Car();
    }
}




• Vehicle :- Abstract Product



public abstract class Vehicle
{

    private int _engineCapacity;
    private int _noOfWheels;

    public int EngineCapacity
    {
        get
        {
            return _engineCapacity;
        }
        set
        {
            _engineCapacity = value;
        }
    }

    public int NoOfWheels
    {
        get
        {
            return _noOfWheels;
        }
        set
        {
            _noOfWheels = value;
        }
    }

    public abstract void Accelerate();

    public abstract void Break();
}




• MotorBicycle, Car :- Concrete Product

public class MotorBicycle : Vehicle
{
    public MotorBicycle()
    {
        base.EngineCapacity = 100;
        base.NoOfWheels = 2;
    }

    public override void Accelerate()
    {
        Console.WriteLine("Accelerating with Handle");
    }

    public override void Break()
    {
        Console.WriteLine("Stopping with Handle");
    }
}

public class Car : Vehicle
{
    public Car()
    {
        base.EngineCapacity = 300;
        base.NoOfWheels = 4;
    }

    public override void Accelerate()
    {
        Console.WriteLine("Accelerating with Paddle");
    }

    public override void Break()
    {
        Console.WriteLine("Stopping with Paddle");
    }
}

• Prorgam :- Cleint

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Creating a Motor Bicycle");
        VehicleFactory bicycleFactory = new BicycleFactory();
        Vehicle motorBicycle = bicycleFactory.CreateVehicle(VehicleFactory.VehicleType.Bicycle);
        Console.WriteLine("Got a " + motorBicycle.GetType() + " with EngineCapacity " + motorBicycle.EngineCapacity + " and " + motorBicycle.NoOfWheels + " wheels.");
        motorBicycle.Accelerate();
        motorBicycle.Break();

        Console.WriteLine("");
        Console.WriteLine("");

        Console.WriteLine("Creating a Car");
        VehicleFactory carFactory = new CarFactory();
        Vehicle car = carFactory.CreateVehicle(VehicleFactory.VehicleType.Car);
        Console.WriteLine("Got a " + car.GetType() + " with EngineCapacity " + car.EngineCapacity + " and " + car.NoOfWheels + " wheels.");
        car.Accelerate();
        car.Break();

        Console.ReadLine();
    }
}