How to make a listview work in Xamarin (VS 2022) - xamarin.android

Question

Here's this code. It sort of runs but then abends. How do I make the choice work? And additionally, I wrote (copied) this code about 18 months ago, so I am vague as to why it seems so backward:
void SwitchNumber()
{
var dialogView = LayoutInflater.Inflate(Resource.Layout.list_view, null);
Android.App.AlertDialog alertDialog;
listview = dialogView.FindViewById<ListView>(Resource.Id.listview);
textview = dialogView.FindViewById<TextView>(Resource.Id.textview);
var items = new string[] { "1","2","3" };
var adapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleListItem1, items);
using (var dialog = new Android.App.AlertDialog.Builder(this))
{
listview.Adapter = adapter;
listview.ItemClick += Listview_ItemClick;
dialog.SetTitle("Switch Number");
dialog.SetMessage("Click on the number you want to switch to");
dialog.SetView(dialogView);
string newNumber = string.Empty;
dialog.SetNegativeButton("Cancel", (s, a) => { });
dialog.SetPositiveButton("OK", (s, a) =>
{
switch (prefs.GetInt("selectitemforAlert", 0))
{
case 0:
newNumber = "1";
break;
case 1:
newNumber = "2";
break;
case 2:
newNumber = "3";
break;
default:
currentNumber = "1";
break;
}
}//switch
);
if (newNumber == currentNumber) return;
ChangeNumber(newNumber);
alertDialog = dialog.Create();
// }
}
//using
dialogView.FindViewById<ListView>(Resource.Id.listview).Adapter = adapter;
alertDialog.Show();
listview.Adapter = adapter;
listview.ItemClick += Listview_ItemClick;
}
The list does appear but I get a null object reference.