views:

3840

answers:

1

I am currently writing a WPF application which does command-line argument handling in App.xaml.cs (which is necessary because the Startup event seems to be the recommended way of getting at those arguments). Based on the arguments I want to exit the program at that point already which, as far as I know, should be done in WPF with Application.Current.Shutdown() or in this case (as I am in the current application object) probably also just this.Shutdown().

The only problem is that this doesn't seem to work right. I've stepped through with the debugger and code after the Shutdown() line still gets executed which leads to errors afterwards in the method, since I expected the application not to live that long. Also the main window (declared in the StartupUri attribute in XAML) still gets loaded.

I've checked the documentation of that method and found nothing in the remarks that tell me that I shouldn't use it during Application.Startup or Application at all.

So, what is the right way to exit the program at that point, i. e. the Startup event handler in an Application object?

+9  A: 

First remove the StartupUri property from App.xaml and then use the following:

    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);

        bool doShutDown = ...;

        if (doShutDown)
        {
            Shutdown(1);
            return;
        }
        else
        {
            this.StartupUri = new Uri("Window1.xaml", UriKind.Relative);
        }
    }
Jakob Christensen
Still doesn't work right :(Specifically I'm getting NullReferenceExceptions in the main window's constructor, which may be easily circumvented. But as far as I understand it shutting down the application should work without instantiating the window referenced by StartupUri.
Joey
I changed my answer to show you how you can avoid your main window to be created. It is important that you first remove the StartupUri from App.xaml.
Jakob Christensen
Thanks. It works now. But I find it kinda unintuitive that the StartupUri is always loaded regardless whether the application should already have exited.
Joey