Shutting down a WPF application from App.xaml.cs

Question

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?

What are the errors you're getting? Please update your question. — Kent Boogaart, Mar 03 '09 at 11:49
Click [Here](http://stackoverflow.com/a/6602102/2342414) for a simple and working answer — benshabatnoam, Mar 01 '16 at 08:45

Jakob Christensen · Accepted Answer · 2009-03-03T12:14:59.997

58

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);
        }
    }

edited Mar 03 '09 at 12:14

answered Mar 03 '09 at 11:49

Jakob Christensen

14,271
1
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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 Mar 03 '09 at 12:00
4

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 Mar 03 '09 at 12:16
1

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 Mar 03 '09 at 13:24
This doesn't work if you are trying to shut down from `InitApplication()`, as in my case. Even if `StartupUri` is null, which it already is in my case because I have no main window, `this.Shutdown()` has no effect. – noobish Aug 31 '11 at 19:25
`InitApplication()` is executed before `OnStartup()`, so I have to set a boolean during `InitApplication()`, then call `return`, and check for the boolean in `OnStartup()` and then exit as above. – noobish Aug 31 '11 at 19:32
When I do this, the program exits but the console window doesn't redraw the console. weird. – Frank Schwieterman Aug 17 '12 at 18:53

score 9 · Answer 2 · answered Feb 15 '13 at 18:14

9

If you remove the StartupUri from app.xaml for an application with a MainWindow you need to make sure you make the following call in your OnStartup method otherwise the application will not terminate when your MainWindow closes.

this.ShutdownMode = System.Windows.ShutdownMode.OnMainWindowClose;

@Frank Schwieterman, something along these lines may help you with your console window issue.

answered Feb 15 '13 at 18:14

FodderZone

863
12
26

This page details the WPF startup and shutdown procedures very clearly... http://www.blackwasp.co.uk/WPFStartupShutdown.aspx – Steve Hibbert Apr 06 '17 at 14:17

score 0 · Answer 3 · answered Jun 11 '20 at 21:56

I did this a little differently to avoid having to set the StartupUri and ShutdownMode properties. First edit the App.xaml file and replace StartupUri with Startup:

<Application x:Class="Menu.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:local="clr-namespace:Menu"
         Startup="Application_Startup">
    <Application.Resources>
    </Application.Resources>
</Application>

Then add Application_Startup to the code along with OnExit:

public partial class App : Application
{
    private volatile static Mutex s_mutex;

    private void Application_Startup(object sender, StartupEventArgs e)
    {
        s_mutex = new Mutex(true, @"Global\MenuMutex", out bool grantedOwnership);

        if (!grantedOwnership)
        {
            MessageBox.Show($"Another instance is already running!", "Error", MessageBoxButton.OK, MessageBoxImage.Exclamation);
            Current.Shutdown();
        }
        else
            new MainWindow().Show();
    }

    protected override void OnExit(ExitEventArgs e)
    {
        s_mutex?.ReleaseMutex();
        s_mutex?.Dispose();
        s_mutex = null;
        base.OnExit(e);
    }

Shutting down a WPF application from App.xaml.cs

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