你遇到这个问题是因为你在Build方法中调用FutureBuilder中的_initializeHive方法，
因此，您必须将_initializeHive和_initializeDummyData移动到initState方法中。
在initState方法中，在Hive初始化后调用_initializeDummyData，
以下是正确代码-

class YourPage extends StatefulWidget {
  @override
  _YourPageState createState() => _YourPageState();
}
class _YourPageState extends State<YourPage> {
  bool isInitialized = false;
  @override
  void initState() {
    super.initState();
    _initializeHiveAndData();
    _checkDietIsViewed();
  }
  Future<void> _initializeHiveAndData() async {
    if (!isInitialized) {
      await HiveService.initHive();
      await _initializeDummyData();
      setState(() {
        isInitialized = true;
      });
    }
  }
  Future<void> _initializeDummyData() async {
    final dietPlans = await HiveService.retrieveDietPlan();
    if (dietPlans.isEmpty) {
      final dummyDietPlan = DietPlan(...); // dummy diet plan inserted
      await HiveService.UpdateDietPlan(dummyDietPlan);
      await HiveService.printDietPlans();
    }
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder<List<DietPlan>>(
        future: HiveService.retrieveDietPlan(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return CircularProgressIndicator();
          } else if (snapshot.hasError) {
            return Text('Error: ${snapshot.error}');
          } else if (!snapshot.hasData || snapshot.data!.isEmpty) {
            return Text('No diet plans available.');
          } else {
            final dietPlans = snapshot.data!;
            return ListView.builder(
              itemCount: dietPlans.length,
              itemBuilder: (context, index) {
                // Build your list item here
              },
            );
          }
        },
      ),
    );
  }
}