i have a list of items which has a default value as false and i am using a checkbox to change the selected item to true, then i am try to add the true key to a list in the shared preferences, but i am getting an error message of 'The argument type 'String' can't be assigned to the parameter type 'List' thank you all

class BallGames extends StatefulWidget {
  @override
  BallGamesState createState() => new BallGamesState();
}

class BallGamesState extends State {
  Map<String, bool> List = {
    'Bubble Football ⚽': false,
    'Futsal