小编Rub*_*lak的帖子

这是main.dart

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
    ]);

    return MaterialApp(
        title: 'List',
        debugShowCheckedModeBanner: false,
        theme: ThemeData(
          primarySwatch: Colors.green,
        ),
        home: HomeScreen());
  }
}

这是主屏幕.dart

class HomeScreen extends StatefulWidget {
  HomeScreen({Key key}) : super(key: key);

  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {

  int _currentindex = 0;
  final List<Widget> screen = [
    DashboardNavigator(),
    RegisterPage(),
  ];

  Future<bool> _onBackPressed() {
  return showDialog(
    context: context,
    builder: (context) => new AlertDialog( …