Question

我被桌面日历困住了。在 Android Studio 中，我收到以下错误：

The following NoSuchMethodError was thrown building StreamBuilder<List<AppEvent>>(dirty, state: _StreamBuilderBaseState<List<AppEvent>, AsyncSnapshot<List<AppEvent>>>#c5581):
The getter 'weekday' was called on null.
Receiver: null
Tried calling: weekday

这是我的代码：如果有必要，我可以发布更多代码，例如类。其他代码完美运行。即使在应用程序的红色问题屏幕中，我也可以触发浮动按钮并添加事件。但是我再也看不到日历导致红色问题屏幕。

import 'package:app_tennis_sv_schwaig/kalender/add_event.dart';
import 'package:app_tennis_sv_schwaig/kalender/event_details.dart';
import 'package:app_tennis_sv_schwaig/kalender/event_firestore_service.dart';
import 'package:app_tennis_sv_schwaig/kalender/app_event.dart';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:table_calendar/table_calendar.dart';

class TennisKalender extends StatefulWidget {
  @override
  _TennisKalenderState createState() => _TennisKalenderState();
}

class _TennisKalenderState extends State<TennisKalender> {
  CalendarController _calendarController = CalendarController();
  Map<DateTime, List<AppEvent>> _groupedEvents;

  _groupEvents(List<AppEvent> events) {
    _groupedEvents = {};
    events.forEach((event) {
      DateTime date =
          DateTime.utc(event.date.year, event.date.month, event.date.day, 12);
      if (_groupedEvents[date] == null) _groupedEvents[date] = [];
      _groupedEvents[date].add(event);
    });
  }

  @override


  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.orange,
      appBar: AppBar(
        backgroundColor: Colors.red,
        title: Text("Tenniskalender"),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.person),
            onPressed: (null),
          )
        ],
      ),
      body: SingleChildScrollView(
        child: StreamBuilder(
          stream: eventDBS.streamList(),
          builder: (BuildContext context, AsyncSnapshot snapshot) {
            if (snapshot.hasData) {
              final events = snapshot.data;
              _groupEvents(events);
              DateTime selectedDate = _calendarController.selectedDay;
              final _selectedEvents = _groupedEvents[selectedDate] ?? [];
              return Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Card(
                    clipBehavior: Clip.antiAlias,
                    margin: const EdgeInsets.all(8.0),
                    child: TableCalendar(
                      calendarController: _calendarController,
                      events: _groupedEvents,
                      onDaySelected: (date, events, holidays) {
                        setState(() {});
                      },
                      startingDayOfWeek: StartingDayOfWeek.monday,
                      headerStyle: HeaderStyle(
                        decoration: BoxDecoration(
                          color: Colors.red,
                        ),
                        headerMargin: const EdgeInsets.only(bottom: 8.0),
                      ),
                    ),
                  ),
                  Padding(
                    padding: const EdgeInsets.only(left: 12.0, top: 8.0),
                    child: Text(
                      DateFormat('EEEE, dd MMMM, yyyy').format(selectedDate),
                      style: Theme.of(context).textTheme.headline6,
                    ),
                  ),
                  ListView.builder(
                    shrinkWrap: true,
                    physics: NeverScrollableScrollPhysics(),
                    itemCount: _selectedEvents.length,
                    itemBuilder: (BuildContext context, int index) {
                      AppEvent event = _selectedEvents[index];
                      return ListTile(
                          title: Text(event.title),
                          subtitle: Text(DateFormat("EEEE, dd MMMM, yyyy")
                              .format(event.date)),
                          onTap: () {
                            Navigator.push(
                              context,
                              new MaterialPageRoute(
                                  builder: (context) => EventDetails(
                                        event: event,
                                      )),
                            );
                          },
                          trailing: IconButton(
                            icon: Icon(Icons.edit),
                            onPressed: () {
                              Navigator.push(
                                  context,
                                  new MaterialPageRoute(
                                      builder: (context) => AddEventPage(
                                            event: event,
                                          )));
                            },
                          ));
                    },
                  ),
                ],
              );
            }
            return CircularProgressIndicator();
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
          child: Icon(
            Icons.add,
            color: Colors.grey[900],
          ),
          backgroundColor: Colors.yellow,
          onPressed: () {
            Navigator.push(
              context,
              new MaterialPageRoute(
                builder: (context) => AddEventPage(
                  selectedDate: _calendarController.selectedDay,
                ),
              ),
            );
          }),
    );
  }
}

我不明白工作日写为空的地方。你能帮忙吗？非常感谢！

Answer 1

我解决了。事实上，其他人也有类似的问题，这是我的解决方案。 DateFormat 中的 ListTile 中的 ListView.builder 是问题所在。不知道为什么，但我删除了它，因为无论如何都不需要应用程序中的视图。

错误命令：

subtitle: Text(DateFormat("EEEE, dd MMMM, yyyy").format(event.date)),

NoSuchMethodError。 getter 'weekday' 被调用为 null。 Table_Calendar Flutter

1 个答案: