how to use async and await on a method that is time comsuming

Question

I have a method like this:

public void ButtonClicked()
{
     var MyResult=MyTimeConsumingTask(MyClassProperty); 
 }

As you can see, it blocks UI thread.

I can create a backgroundWorker and run this method on that background thread, but I am looking to see if using Async and Await would help me to simplify this.

This is not working:

public async void ButtonClicked()
{
    await var MyResult=MyTimeConsumingTask(MyClassProperty); 
}

How can I do this?

I like to know the general solution, but also noting that MyimeConsumingTask is waiting for some data on network, how can I solve the problem?

`var MyResult = await Task.Run(() => MyTimeConsumingTask(MyClassProperty));` — EZI, Jul 10 '14 at 15:17
"This is not working" is never enough information. I suspect you just want `var myResult = await MyTimeConsumingTask(MyClassProperty);` but you should *always* specify the error in the question. — Jon Skeet, Jul 10 '14 at 15:19
possible duplicate of [How to call any method asynchronously in c#](http://stackoverflow.com/questions/5563299/how-to-call-any-method-asynchronously-in-c-sharp) — user247702, Jul 10 '14 at 15:19
What do you want to happen when the button is clicked? I assume that something should happen on the UI, when the `MyTimeConsumingTask` has finished? I'm also assuming that the UI should not block? — Jonny, Jul 10 '14 at 15:21
@Stijn I don't believe that is a valid duplicate as this question explicitly asks (badly) about `async/await` which that question doesn't cover (as it was asked before the feature became available). — Daniel Kelley, Jul 10 '14 at 15:23
@EZI Thanks for answer. What I was missing was the inclusion of Task.Run.. which is working now. Please add it as an answer and I will accept it. — mans, Jul 10 '14 at 15:32
@DanielKelley It does answer the question with the [bottom answer](http://stackoverflow.com/a/24241619/247702). The answer doesn't use `await`, but that's not necessary here I believe. — user247702, Jul 10 '14 at 15:33
@Stijn That question is not similar as my question was how to use async and await, but the other question was how to use any method to run async. — mans, Jul 10 '14 at 15:34
Just another question: In other question it say that async and await would be in c#5, but as far as I know it is available in c#4.5 am I wrong? — mans, Jul 10 '14 at 15:36
@mans sure you asked for `async` and `await` because you thought that was the way to solve it. But really you're asking how to run your method asynchronous. — user247702, Jul 10 '14 at 15:36
@Stijn I also mentioned that I can use backgroundworker to do it, but my question is specifically how to do it using async and await — mans, Jul 10 '14 at 15:38
@mans fair enough, I'll remove the close vote. Regarding your previous comment, C# 4.5 does not exist. The framework supports it in .NET 4.5 and C# supports the syntax with C# 5 ([see here](http://stackoverflow.com/questions/13179923/which-net-version-for-c-sharp-5-async-features)). — user247702, Jul 10 '14 at 15:38
Sounds like you simply need to go look at some basic tutorials on the topic. — Servy, Jul 10 '14 at 19:43

score 4 · Accepted Answer · edited Jul 10 '14 at 23:21

To be able to await MyTimeConsumingTask it must be declared to return a Task.

public async Task<SimeType> MyTimeConsumingTask()

Since you said it does some network IO, you can rewrite it using async NW IO methods and then await it as

var MyResult = await MyTimeConsumingTask(MyClassProperty);

But in your case the simplest approach seems to be using Task.Run

var MyResult = await Task.Run(() => MyTimeConsumingTask(MyClassProperty));

Comparing these two approaches:

1.

public async Task<string> GetHtmlAsync(string url)
{
    using (var wc = new Webclient())
    {
        var html = await wc.DownloadStringTaskAsync(url);
        //do some dummy work and return
        return html.Substring(1, 20);
    }
}

var str1 = await GetHtmlAsync("http://www.google.com");

2.

public string GetHtml(string url)
{
    using (var wc = new Webclient())
    {
        var html = wc.DownloadString(url);
        //do some dummy work and return
        return html.Substring(1, 20);
    }
}

var str2 = await Task.Run(()=>GetHtml("http://www.google.com"));

I would definitely prefer the first one, but the 2nd one is easier to use if it is already working and hard to change method.

how to use async and await on a method that is time comsuming

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