How to create a alert in MAUI - Platform specific - Android.

Question

Hello Team,

I want to reuse the existing alert which is created in Xamarin-Android, When I'm trying to access that. Facing this exception.

Please find the below code:

Device.BeginInvokeOnMainThread(() =>
{
	AlertDialog.Builder dialog = new AlertDialog.Builder
	(context);
	dialog.SetCancelable(false);
	dialog.SetTitle("Update Available");
	dialog.SetMessage("A new version of this application is available. " +
		"Please update to the new version now.");
	dialog.SetPositiveButton("Update", (sender, e) =>
	{
		context.StartActivity(new Intent(
			Intent.ActionView,
			Android.Net.Uri.Parse
				(string.Format(appSpecificStoreLink, context.PackageName))));

		Process.KillProcess(Process.MyPid());
		System.Environment.Exit(0);
	});
	dialog.Show();
});

Exception : Android.Views.WindowManagerBadTokenException: 'Unable to add window -- token null is not valid; is your activity running?'

How to fix this.

Thanks
Vaibhav Methuku.

Answer 1

Hello,

Firstly, Device.BeginInvokeOnMainThread is obsolete. Please use MainThread.BeginInvokeOnMainThread.

And use Platform.CurrentActivity to replace of Context. Here is my edited code. You can refer to it.

    MainThread.BeginInvokeOnMainThread(() =>

            {
#if ANDROID
                AndroidX.AppCompat.App.AlertDialog.Builder dialog = new AndroidX.AppCompat.App.AlertDialog.Builder

                (Platform.CurrentActivity);

                dialog.SetCancelable(false);

                dialog.SetTitle("Update Available");

                dialog.SetMessage("A new version of this application is available. " +

                    "Please update to the new version now.");

                dialog.SetPositiveButton("Update", (sender, e) =>

                {
                    Android.Content.Intent intent = new Android.Content.Intent(Android.Content.Intent.ActionView, Android.Net.Uri.Parse(string.Format(appSpecificStoreLink, (Platform.CurrentActivity.PackageName))));

                    Platform.CurrentActivity.StartActivity(intent);

                    Android.OS.Process.KillProcess(Android.OS.Process.MyPid());

                    System.Environment.Exit(0);

                });

                dialog.Show();
#endif
            });

Best Regards,

Leon Lu

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