using System;

using System.Threading.Tasks;

​

public class Program

{

    private static int counter = 0;

    public static void Main()

    {

        Random rnd = new Random();

        var tasks = new Task<object>[]

        {

            CreateTask(rnd.Next(500,2000)).ContinueWith(t => (object)t.Result),

            CreateOtherTask(rnd.Next(500,2000)).ContinueWith(t => (object)t.Result),

            CreateTask(rnd.Next(500,2000)).ContinueWith(t => (object)t.Result),

            CreateOtherTask(rnd.Next(500,2000)).ContinueWith(t => (object)t.Result),

            Task.Run(() => (object)CreateSimple()),

            Task.Run(() => (object)CreateMessage()),

            Task.Run(() => (object)CreateSimple()),

            Task.Run(() => (object)CreateMessage())

        };      

        Task.WaitAll(tasks);

        foreach(var t in tasks)

            Console.WriteLine(t.Result);

        // They are already completed here, but just to show the syntax.

        // .Result should obvisously be awaited instead.

        var all = Task.WhenAll(tasks).Result;

        foreach(var result in all)

            Console.WriteLine(result);

    }

​

​

    private static string CreateSimple()

    {

        int id = Program.counter++;

        return "Task [" + id + "] delayed: NONE";

    }

    private static Message CreateMessage()

    {

        return new Message(CreateSimple());

    }

​

    private static async Task<string> CreateTask(int delay)

    {

        int id = Program.counter++;

        await Task.Delay(delay);

        return "Task [" + id + "] delayed: " + delay;

    }

​

    private static async Task<Message> CreateOtherTask(int delay)

    {

        int id = Program.counter++;

        await Task.Delay(delay);

        return new Message("Task [" + id + "] delayed: " + delay);

    }

    public class Message {

        private string message;

        public Message(string msg) { message = msg; }

        public override string ToString(){ return message; }

    }

}