Question

I know it is bad to call Task.Wait in UI thread. It causes a deadlock. Please refer to

Constructor invoke async method

Await, and UI, and deadlocks! Oh my!

Take the following code:

    public MainPage()
    {
        this.InitializeComponent();

        step0();
        step1();
    }

    private async Task step0()
    {
        await Task.Delay(5000);
        System.Diagnostics.Debug.WriteLine("step 0");
    }

    private async Task step1()
    {
        await Task.Delay(3000);
        System.Diagnostics.Debug.WriteLine("step 1");
    }
}

How can I ensure that “step 0” is always being printed before “step 1”? Using Task.Wait would cause deadlock. This is Windows Store App

Answer 1

You can use Task.ContinueWith to chain the tasks together so that they happen sequentially.

public MainPage()
{
    this.InitializeComponent();

    step0().ContinueWith(t => step1());
}

Also, Alexei’s comment is correct. Task.Wait will block the UI thread. Deadlocks are something else.