using System;

​

public class Program

{

    public class Test<T>

    {

        public static T DefaultValue;

        static Test()

        {

            if (typeof(T) == typeof(string))

            {

                Console.WriteLine("Is a string.");

            }

            else if (typeof(T) == typeof(int))

            {

                Console.WriteLine("Is NOT a string.");

            }

        }

    }

    public static void Main(string[] args)

    {

        Console.WriteLine(Test<int>.DefaultValue);

        Console.WriteLine(Test<string>.DefaultValue ?? "<null>");

    }

}