How to show displayName of contact as text?

Question

I want to pick a random number from contact list and show it as Text. Below is what I came up with but when I insert showNext() somewhere on main.dart as text, I get Closure: () => Future from Function 'showNext': static.() instead of a number. How do I show a number?

Future<void> showNext() async {
  var status = await Permission.contacts.status;
    if (status.isGranted) {
  var contacts = await ContactsService.getContacts;
  var list = contacts;
    list.shuffle();
  randomNum= (list.first.phones?.first.value ?? '');
  Text('$randomNum');