Howto use a task to display a delayed text

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I'am doing some simple tests with Task.Run in C# 5.0. I have created a Form with a button and label to test it. Should be quite simple, but couldn't get it work so far.

How can i write delayed into the label without blocking the ui ?

Here is my sample code:

private void Button_Click(object sender, EventArgs e)
{
    writeStatus("test 1");
}

private Task taskWriteStatus(string text)
{
    return Task.Run (() =>
    {
        labelWrite(text);
    }); 
}

private void labelWrite(string text)
{
    Task.Delay(300).Wait();
    label1.Text = text;
}

private async void writeStatusAsync (string text)
{
    await taskWriteStatus(text);
}

What I have tried:

I did some research and found differnat approaches to solve this like this good article:
https://blog.imaginea.com/elegant-c-asynchrony/

Posted 30-May-17 12:33pm

Member 13158148

Updated 30-May-17 18:02pm

VR Karthikeyan

v2

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VR Karthikeyan · Accepted Answer · 2017-05-30T18:02:00

Hi, You cannot access UI thread straight away from another thread, UI thread has highest priority. You need to use dispatcher to do it.

just change your labelWrite(string text) method,

C#

private void labelWrite(string text)
{
    Task.Delay(10000).Wait();
    this.Invoke(new MethodInvoker(delegate ()
    {
        label1.Text = text;
    }));
}

And call this method in Button Click. Always try to use dispatcher when you need to update UI from threads.