Program.cs

using System;

namespace FactoryMethod;
// Product interface
public interface IDocument
{
    void Open();
    void Save();
}

// Concrete Products
public class PdfDocument : IDocument
{
    public void Open() => Console.WriteLine("Opening PDF document");
    public void Save() => Console.WriteLine("Saving PDF document");
}

public class WordDocument : IDocument
{
    public void Open() => Console.WriteLine("Opening Word document");
    public void Save() => Console.WriteLine("Saving Word document");
}

// Creator (abstract class)
public abstract class DocumentCreator
{
    // Factory Method
    public abstract IDocument CreateDocument();

    public void ProcessDocument()
    {
        IDocument doc = CreateDocument();
        doc.Open();
        doc.Save();
    }
}

// Concrete Creators
public class PdfDocumentCreator : DocumentCreator
{
    public override IDocument CreateDocument()
    {
        return new PdfDocument();
    }
}

public class WordDocumentCreator : DocumentCreator
{
    public override IDocument CreateDocument()
    {
        return new WordDocument();
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("=== Factory Method Pattern Demo ===");
        Console.WriteLine();

        DocumentCreator creator;

        // Create and process a PDF document
        Console.WriteLine("Creating PDF document:");
        creator = new PdfDocumentCreator();
        creator.ProcessDocument();

        Console.WriteLine();
        Console.WriteLine("Creating Word document:");
        creator = new WordDocumentCreator();
        creator.ProcessDocument();

        Console.WriteLine();
        Console.WriteLine("Press any key to exit...");
        Console.ReadKey();
    }
}