Factory Design Pattern C#

This short article show you the code to implement the Factory Design Pattern in C#.

This is actually the summarize version of this https://msdn.microsoft.com/en-us/library/ee817667.aspx. In the original article there is no downloadable code.

At first we look at the diagram, the logical model.

clip_image001

The class diagram is like below.

clip_image002

We then create the Factory, abstract class (the class name will be your file name).

abstract class ComputerFactory

{

    public abstract Computer GetComputer();

 

}//ComputerFactory

We create the Computer (the product), abstract class.

abstract class Computer

{

    public abstract int Mhz { get; }

 

}//Computer

Now we implement the factory.

class ConcreteComputerFactory : ComputerFactory

{

    public override Computer GetComputer()

    {

        return new ConcreteComputer();

    }//GetComputer

 

}//ConcreteComputerFactory

We implement the product.

class ConcreteComputer : Computer

{

    int _mhz = 500;

    public override int Mhz

    {

        get { return _mhz; }

    }//Mhz

}//ConcreteComputer

Implement another factory.

class BrandXFactory : ComputerFactory

{

    public override Computer GetComputer()

    {

        return new BrandXComputer();

    }//GetComputer

}

Implement another product.

class BrandXComputer : Computer

{

    int _mhz = 1500;

    public override int Mhz

    {

        get { return _mhz; }

    }//Mhz

}//BrandXComputer

The main program is below.

class Program

{

    class ComputerAssembler

    {

        public void AssembleComputer(ComputerFactory factory)

        {

            Computer computer = factory.GetComputer();

            Console.WriteLine(“assembled a {0} running at {1} MHz”,

               computer.GetType().FullName, computer.Mhz);

        }//AssembleComputer

    }//ComputerAssembler

    static void Main(string[] args)

    {

        ComputerFactory factory = null;

        if (args.Length > 0 && args[0] == “BrandX”)

            factory = new BrandXFactory();

        else

            factory = new ConcreteComputerFactory();

        new ComputerAssembler().AssembleComputer(factory);

    }

}

You can also download a single solution from http://skydrive.live.com. The sample file name is ConAppFactory.zip My MSN ID is chanmmn@hotmail.com.

About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress (http://www.pcworld.com/article/206455/Microsoft_Live_Spaces_Moves_to_WordPress_An_FAQ.html) till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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