In this design pattern interface is used to create an object but let the subclass decide which class to instantiate

Factory design pattern we will create the base interface called as factory

After that we will create the methods associated with it

Then we will create the classes that will implement these interfaces and invoke these classes

    using System;
    namespace Factory
    {
     /// <summary>
     /// The 'Product' interface
     /// </summary>
     public interface IFactory
     {
     void Drive(int miles);
     }
     
     /// <summary>
     /// A 'ConcreteProduct' class
     /// </summary>
     public class Scooter : IFactory
     {
     public void Drive(int miles)
     {
     Console.WriteLine("Drive the Scooter : " + miles.ToString() + "km");
     }
     }
     
     /// <summary>
     /// A 'ConcreteProduct' class
     /// </summary>
     public class Bike : IFactory
     {
     public void Drive(int miles)
     {
     Console.WriteLine("Drive the Bike : " + miles.ToString() + "km");
     }
     }
     
     /// <summary>
     /// The Creator Abstract Class
     /// </summary>
     public abstract class VehicleFactory
     {
     public abstract IFactory GetVehicle(string Vehicle);
     
     }
     
     /// <summary>
     /// A 'ConcreteCreator' class
     /// </summary>
     public class ConcreteVehicleFactory : VehicleFactory
     {
     public override IFactory GetVehicle(string Vehicle)
     {
     switch (Vehicle)
     {
     case "Scooter":
     return new Scooter();
     case "Bike":
     return new Bike();
     default:
     throw new ApplicationException(string.Format("Vehicle '{0}' cannot be created", Vehicle));
     }
     }
     
     }
     
     /// <summary>
     /// Factory Pattern Demo
     /// </summary>
     class Program
     {
     static void Main(string[] args)
     {
     VehicleFactory factory = new ConcreteVehicleFactory();
     
     IFactory scooter = factory.GetVehicle("Scooter");
     scooter.Drive(10);
     
     IFactory bike = factory.GetVehicle("Bike");
     bike.Drive(20);
     
     Console.ReadKey();
     
     }
     }
    }