Flutter Dart 继承类并在父类的函数中使用

我想创建一个使用ChangeNotifier的父类.从这个类中，我想创建两个单独的继承类，它们将为应用程序的某些部分提供列表数据，每个类都有自己的单独列表.但我无法理解每个类如何创建自己的列表，并且只能通过使用超类对该列表进行操作.有人能给我解释一下我该怎么做吗？

import 'package:flutter/material.dart';

class ObjectListProvider<T extends num, K extends Object> with ChangeNotifier {
  final Map<T, K> _map = {};

  Map<T, K> get map {
    return {..._map};
  }

  K? getSingleObjectWithId(id) {
    return _map[id];
  }

  void add(T id, K obj) {
    _map[id] = obj;
    notifyListeners();
  }

  void remove(T id) {
    _map.remove(id);
    notifyListeners();
  }
}

import 'object_list_provider.dart';
import '../person.dart';

class PersonList extends ObjectListProvider {
  final Map<dynamic, Person> _people = {};
}

import './object_list_provider.dart';
import '../group.dart';
import '../person.dart';

class GroupList extends ObjectListProvider {
  final Map<dynamic, Group> _groups = {};

  void addPersonToGroup<T extends num>(Person person, T id) {
    super.add(id, person);
    notifyListeners();
  }

  void removePersonFromGroup<T extends num>(Person person, T id) {
    _groups[id]?.removePerson(id);
    notifyListeners();
  }
}

import './person.dart';
import './transaction.dart';

class Group {
  final int _id;
  String _name;
  List<Person> _people = [];
  List<Transaction> _transactions = [];
  int _totalSpending;

  Group({required int id, required String name, int totalSpending = 0})
      : _id = id,
        _name = name,
        _totalSpending = totalSpending;

  int get id {
    return _id;
  }

  String get name {
    return _name;
  }

  int get totalSpending {
    return _totalSpending;
  }

  set name(String newName) {
    _name = newName;
  }

  void addPerson(Person person) {
    _people.add(person);
  }

  void removePerson<T extends num>(T id) {
    _people = _people.where((Person person) => person.id != id).toList();
  }

  void addTransaction(Transaction transaction) {
    _transactions.add(transaction);
  }
}

class Person {
  final int _id;
  final String _name;
  int _balance;
  List<int> involvedGroups = [];

  Person({required int id, required String name, int balance = 0})
      : _id = id,
        _name = name,
        _balance = balance;

  int get id {
    return _id;
  }
}

例如，我将在其他dart文件中使用此提供程序作为

final groupList = Provider.of<GroupList>(context);
groupList.add(....)