Factory-CSharp.cs

// Factory Method
public interface Human {
    String getName();
}

/// Tanaka Factory
sealed class TanakaImpl : Human {
    public string getName() {
        return "Tanaka";
    }
}

sealed public class TanakaFactory {
    public static Human getInstance() {
        return new TanakaImpl();
    }
}

/// Tanaka Factory
sealed class YamadaImpl : Human {
    public string getName() {
        return "Yamada";
    }
}

sealed public class YamadaFactory {
    public static Human getInstance() {
        return new YamadaImpl();
    }
}

Human human = TanakaFactory.getInstance();
Console.WriteLine(human.getName()); // Tanaka

human = YamadaFactory.getInstance();
Console.WriteLine(human.getName()); // Yamada