Winform label text not showing

Question

I have following code:

Hide()
if(a > b)
{
label.Text = "a is greater than b";
Show();
Thread.Sleep(50000);
}

What i am trying to do is hide the winform as soon as app starts. If a>b at any point it will show the winform with that message in the label for 50 second and will hide again. Also label is set to autosize = true;

Above code works but label is not showing any text? Also is this the right approch to show the winfor for sometime using thread sleep?

Answer 1

Thorsten is right, Sleep is freezing the UI thread, so the UI is not refreshed, but you could also do something like this as a workaround:

Hide()
if(a > b)
{
    label.Text = "a is greater than b";
    Show();
    Refresh();
    Thread.Sleep(5000);
}

But the cleanest solution of course is:

Hide()
if(a > b)
{
    label.Text = "a is greater than b";
    Show();
    Task.Factory
        .StartNew(() => Thread.Sleep(5000))
        .ContinueWith(() => Close(), TaskScheduler.FromCurrentSynchronizationContext());
}

But don't forget to add the proper using clause to use the Task Parallel Library:

using System.Threading.Tasks;

The TPL is available in .NET 4 onwards. More info here: http://msdn.microsoft.com/en-us/library/dd460717.aspx