Factory Design Pattern in C# with example

This video is about Factory Design Pattern in C# with example. Here you will learn what is design pattern, what is factory design pattern - its Creational design Pattern, I will show you simple example without its implementation that means traditional approach and then I will show you implementing the same code using Factory design pattern.

Traditional way Code implementation without Factory Design Pattern:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WithoutFactory
{
    class Program
    {
        static void Main(string[] args)
        {
            Igym obj = null;
            Console.WriteLine("Which Membership you want?");
            string type = Console.ReadLine();
            if (type == "monthly")
            {
                obj = new Monthly();
            }
            else if (type == "yearly")
            {
                obj = new Yearly();
            }
            Console.WriteLine(obj.getcharges());
            Console.ReadLine();
        }
    }
    public interface Igym
    {
        int getcharges();
    }
    public class Monthly : Igym
    {
        public int getcharges()
        {
            return 2000;
        }
    }
    public class Yearly : Igym
    {
        public int getcharges()
        {
            return 8000;
        }
    }  
}

Code implementation with Factory Design Pattern:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WithFactory
{
    class Program
    {
        static void Main(string[] args)
        {
            MembershipFactory obj = new ConcreteMembership();
            Console.WriteLine("which membership charges you want?");
            string type = Console.ReadLine();
            Igym instance = obj.GetGymMembershipType(type);
            Console.WriteLine(instance.getcharges());
            Console.ReadLine();
        }
    }
    public interface Igym
    {
        int getcharges();
    }
    public class Monthly : Igym
    {
        public int getcharges()
        {
            return 2000;
        }
    }
    public class Yearly : Igym
    {
        public int getcharges()
        {
            return 8000;
        }
    }

    public abstract class MembershipFactory //Factory class - Creator
    {
        public abstract Igym GetGymMembershipType(string type);
    }
    public class ConcreteMembership : MembershipFactory //Concrete Creator
    {
        public override Igym GetGymMembershipType(string type)
        {
            switch (type)
            {
                case "monthly":
                    return new Monthly();
                case "yearly":
                    return new Yearly();
                default:
                    throw new ApplicationException(string.Format("membership'{0}' not available", type));
            }
        }
    }
}

Here you saw the difference in traditional way of code implementation and implementing factory design pattern- Factory Design Pattern in C# with example