Xamarin.Android Launching Apps with Package Name

Question

I am trying to build a Home Launcher App in Xamarin

Currently I have a Xamarin Forms App with Access to Xamarin Android through interfaces. In Xamarin Android I have a method to find all package Names on the device like this:

[assembly: Xamarin.Forms.Dependency(typeof(Launcher.Droid.GetLauncher))]
namespace Launcher.Droid
{
    class GetLauncher : MainActivity,IGetLauncher
    {
        
        public string GetPackageName(int index)
        {
            var apps = Android.App.Application.Context.PackageManager
                .GetInstalledApplications(PackageInfoFlags.MatchAll);
        
            return apps[index].PackageName; ;
        }
    }
}

I can access this function from Xamarin Forms to get the package names.

Now I want to launch an App with a certain package Name:

I have tried the following code also in Xamarin Android accessed by an Interface from Xamarin Forms:

[assembly: Xamarin.Forms.Dependency(typeof(Launcher.Droid.GetLauncher))]
namespace Launcher.Droid
{
    class GetLauncher : MainActivity,IGetLauncher
    {
        public void RunApp(int index)
        {
            var apps = Android.App.Application.Context
                .PackageManager.GetInstalledApplications(PackageInfoFlags.MatchAll);

            Intent intent = 
                PackageManager.GetLaunchIntentForPackage(apps[index].PackageName);

            StartActivity(intent);
        }    
    }
}

which results in the following error:

Java.Lang.NullPointerException Nachricht = Attempt to invoke virtual method 'android.content.pm.PackageManager android.content.Context.getPackageManager()' on a null object reference

The Error occurs on the PackageManager.GetLaunchIntentForPackage Line. I am testing on a physical device.

Any Help or hints would be highly appreciated.

Answer 1

Try to change your codes like below:

[assembly: Xamarin.Forms.Dependency(typeof(Launcher.Droid.GetLauncher))]

namespace Launcher.Droid
{
   class GetLauncher :  IGetLauncher
   {
     public void RunApp(int index)
     {
        var apps = Android.App.Application.Context.PackageManager.GetInstalledApplications(PackageInfoFlags.MatchAll);
        Intent intent = Android.App.Application.Context.PackageManager.GetLaunchIntentForPackage(apps[index].PackageName);
        Android.App.Application.Context.StartActivity(intent);
     }
   }
}