using System;

using System.Threading;

using System.Threading.Tasks;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var myObj = new MyObj{Value = 1};

        //Start a task that takes a while

        var task1 = Print(myObj, 1000);

        // Value gets set to null

        myObj.Value = null;

        // task1 will print "null"

        Task.WaitAll(task1);

    }

​

    // Waits for the duration and then prints myObj.Value

    public static async Task Print(MyObj myObj, int waitDuration)

    {

        await Task.Run(() => Thread.Sleep(waitDuration));

        Console.WriteLine(myObj.Value == null ? "null" : myObj.Value.ToString());

    }

​

    public class MyObj

    {

        public int? Value { get; set; }

    }

}