Mahesh InFO: C# Design Patterns Tutorial Real-time example of Factory Pattern

Monday, September 29, 2025

🏭 Factory Design Pattern in C# with Real-Time Example

📌 What is the Factory Design Pattern?

The Factory Design Pattern is a creational pattern used in object-oriented programming to abstract the process of object creation. Instead of instantiating classes directly using new, the Factory Pattern provides a method that returns instances of different classes based on input parameters.

This pattern is especially useful when:

The exact type of object to create is determined at runtime.
You want to encapsulate object creation logic.
You need to adhere to the Open/Closed Principle (open for extension, closed for modification).

🚗 Real-Time Example: Vehicle Factory in C#

Imagine you're building a transportation management system that handles different types of vehicles: Car, Bike, and Truck. Each vehicle has its own behavior, but the client code shouldn't worry about how these objects are created.

✅ Step-by-Step Implementation

1. Define a Common Interface

public interface IVehicle
{
    void Start();
}

2. Create Concrete Implementations

public class Car : IVehicle
{
    public void Start()
    {
        Console.WriteLine("Car started.");
    }
}

public class Bike : IVehicle
{
    public void Start()
    {
        Console.WriteLine("Bike started.");
    }
}

public class Truck : IVehicle
{
    public void Start()
    {
        Console.WriteLine("Truck started.");
    }
}

3. Implement the Factory Class

public static class VehicleFactory
{
    public static IVehicle GetVehicle(string vehicleType)
    {
        switch (vehicleType.ToLower())
        {
            case "car":
                return new Car();
            case "bike":
                return new Bike();
            case "truck":
                return new Truck();
            default:
                throw new ArgumentException("Invalid vehicle type");
        }
    }
}

4. Client Code

class Program
{
    static void Main(string[] args)
    {
        IVehicle vehicle1 = VehicleFactory.GetVehicle("car");
        vehicle1.Start();

        IVehicle vehicle2 = VehicleFactory.GetVehicle("bike");
        vehicle2.Start();
    }
}

🎯 Benefits of Using Factory Pattern in C#

Encapsulation: Object creation logic is hidden from the client.
Scalability: Easily add new vehicle types without changing client code.
Maintainability: Centralized object creation makes debugging and updates easier.
Loose Coupling: Promotes interface-based programming.

📝 Final Thoughts

The Factory Design Pattern is a cornerstone of clean, scalable software architecture. Whether you're building enterprise applications or small utilities, this pattern helps you write flexible and maintainable code.

Mahesh InFO