Not seeing output after using Task delay

Question

I am using an online editor for testing some C# code : https://repl.it/ I am not able to get the task after Task.Delay. Why is this C# code not working as intended?

using System.IO;
using System;
using System.Reflection;
using System.Threading.Tasks;

class Input {

   public Input() {

   }

   public async void  hello()
   {
    Console.WriteLine("some task");
   await Task.Delay(1000);
   Console.WriteLine("after some time");
     }


}

class SomeExample {
   public static void Main(string[] args) {

      Input std1 = new Input( );
      std1.hello();
   }
}

You have `async void` return type instead of `async Task` – Pavel Anikhouski Jan 12 '20 at 18:50 — Pavel Anikhouski, Jan 12 '20 at 18:50

score 2 · Answer 1 · answered Jan 12 '20 at 18:57

2

Method hello should return Task, not void. Method Main should be async Task to be able to await hello. Also you need to await std1.hello() call:

public async Task hello()
{
    Console.WriteLine("some task");
    await Task.Delay(1000);
    Console.WriteLine("after some time");
}

public static async Task Main(string[] args) 
{
  Input std1 = new Input( );
  await std1.hello();
}

What you have now is situation when Main method finishes its execution before hello method (because it not awaited).

answered Jan 12 '20 at 18:57

Alexander Goldabin

1,824
15
17

It does not seem to work here: https://repl.it/@VishwasGagrani/TaskDelay – Vishwas Jan 13 '20 at 03:45
std1.hello().Wait() works. But not await std1.hello() ; – Vishwas Jan 13 '20 at 03:49
https://repl.it/@VishwasGagrani/TaskDelay - what is currently here is synchronous code which blocks main thread on `.Wait()` – Alexander Goldabin Jan 13 '20 at 05:34

sachin soni · Accepted Answer · 2020-01-12T19:22:17.967

Fixes: Change your method return type from void to Task. Make the console wait by adding Console.ReadLine() so that you can see the output ("after some time") and lastly, tell the method to wait and don't finish execution by adding Wait(). Hope this works.

class Input
{
    public Input()
    {

    }

    public async Task hello()
    {
        Console.WriteLine("some task");
        await Task.Delay(1000);
        Console.WriteLine("after some time");
        Console.ReadLine();
    }
}

class SomeExample
{
    public static void Main(string[] args)
    {
        Input std1 = new Input();
        std1.hello().Wait();
    }
}

score -1 · Answer 3 · answered Jan 13 '20 at 05:05

-1

For now it seems this code is doing my work. I don't need to use async or Task keywords.

using System.IO;
using System;

using System.Threading.Tasks;
class Input
{
    public Input()
    {

    }

    public void   hello()
    {
        Console.WriteLine("some task");
           Task.Delay(1000).Wait();
        Console.WriteLine("after some time");

    }


}

class SomeExample
{
    public static void Main(string[] args)
    {
        Input std1 = new Input();
        std1.hello() ;

    }
}

answered Jan 13 '20 at 05:05

Vishwas

1,533
2
19
40

This code is synchronous. You don't need to use Task.Delay(1000).Wait. Instead you'd better use Thread.Sleep(1000). You would need async/Tasks if you want your code to be asynchronous. You could read this for more details: https://stackoverflow.com/a/28413138/4553518 – Alexander Goldabin Jan 13 '20 at 05:38

Not seeing output after using Task delay

3 Answers3