＆＃x27;更改Notifier提供商＆＃x27; ISN＆＃x27; ta功能错误消息

Question

我正在构建一个拼写应用程序。这是给我一个错误的代码。我不知道我在做什么错。

void main() {
  runApp(ChangeNotifierProvider(create: (_) => Controller(), child: MyApp()));
}

错误消息是

'changeNotifierProvider'不是函数。

Answer 1

您应该使用MultileProvider

这样...

void main() {
  runApp(const MyApp());
}

和MyApp类使用MultieProvider。

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MultiProvider(
      providers: [
        ChangeNotifierProvider<GetProvider>(create: (context) => GetProvider()),
      ],
      builder: (context, child) {
        return const MaterialApp(
          home: HomeScreen(),
        );
      },
    );
  }
}

Answer 2

您可以这样做：

class Person with ChangeNotifier {
  Person({this.name, this.age});

  final String name;
  int age;

  void increaseAge() {
    this.age++;
    notifyListeners();
  }
}

// here, you can see that the [ChangeNotifierProvider]
// is "wired up" exactly like the vanilla [Provider]
void main() {
  runApp(
    ChangeNotifierProvider(
      create: (_) => Person(name: "Yohan", age: 25),
      child: MyApp(),
    ),
  );
}

---

Answer 3

void main() {

  runApp( MyApp());

}

class MyApp extends StatelessWidget {
   MyApp({Key? key}) : super(key: key);
 
  @override
  Widget build(BuildContext context) {

    return ChangeNotifierProvider(
      create: (context) => ThemeProvider(),
      builder: (context, _) {
        final provider = Provider.of<ThemeProvider>(context);
        return MaterialApp(
          title: 'Flutter Demo',
          theme: provider.darkMode ? darkMode : lightMode,
        );
      },
    );
  }
}