Callback from Async Task

Program.cs

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace TaskWithCallback
{
	class Program
	{
		private static readonly object Obj = new object();

		static void Main(string[] args)
		{
			var tasks = new List<Task>
			{
				Task.Factory.StartNew(() => Run(Callback)),
				Task.Factory.StartNew(() => Run(Callback))
			};

			Task.WaitAll(tasks.ToArray());
		}

		private static void Run(Action<Result> callback)
		{
			var result = new Result();

			result.DtInicio = DateTime.Now;
			result.Total = new Random().Next();
			Thread.Sleep(new Random().Next(100, 3000));

			result.DtFinal = DateTime.Now;

			callback(result);
		}

		private static void Callback(Result result)
		{
			lock (Obj)
			{
				Console.WriteLine(result.DtInicio.ToString("dd/MM/yyyy HH:mm:sss"));
				Console.WriteLine(result.Total);
				Console.WriteLine(result.DtFinal.ToString("dd/MM/yyyy HH:mm:sss"));
			}
		}
	}

	class Result
	{
		public DateTime DtInicio { get; set; }
		public DateTime DtFinal { get; set; }
		public int Total { get; set; }
	}
}