I have initializeThemeData() which returns ThemeData for the whole app.

# main.dart

Future<ThemeData> initializeThemeData() async {
  
  
  return ThemeData(
    scaffoldBackgroundColor: Color(Client().getBackgroundColor()),
    );
}

This ThemeData() uses a background color of Client().getBackgroundColor():

# get_client_settings.dart 

class Client {
  getBackgroundColor() async {
    var settings = await getSettings();
    var hexColor = settings["view_background_color"];
    return int.parse("0xFF" + hexColor.substring(1));
  }
}

Client class awaits another method called getSettings which returns a json:

# load_settings.dart 

getSettings() async {
  String jsonData =
      await rootBundle.loadString('assets/config/client_settings.json');
  Map<String, dynamic> data = jsonDecode(jsonData);
  return data;
}

getSettings loads the json from a json file which has the backgroundcolor value i want to use:

{
   "view_background_color" : "#f5f242" 
}

But when i run the app i get the error: type 'Future<dynamic>' is not a subtype of type 'int'

EDIT:

I know it has to do with the Future and i should use FutureBuilder
There is similar question in the link How to fix type 'Future<dynamic>' is not a subtype of type 'String' Flutter

But if i have to use FutureBuilder, how can i then use it for my situation without placing everything in one file?

>Solution :

I think it should be a int instead of Future

scaffoldBackgroundColor: Color(await Client().getBackgroundColor()),