Flutter：如何从另一个类调用实例的方法

Question

我正在尝试创建一个使用Tab管理视图的应用程序。
导航栏和标签栏显示在应用程序中，要显示的内容的内容由列表管理。

这是管理Tab内容的类。

class TabItem {
  TabItem({
    Widget view,
    Widget icon,
    Widget activeIcon,
    String title,
    TickerProvider vsync,
  })  : _view = view,
        _title = title,
        item = BottomNavigationBarItem(
          icon: icon,
          // activeIcon: activeIcon,
          title: Text(title),
        ),
        controller = AnimationController(
          duration: kThemeAnimationDuration,
          vsync: vsync,
        ) {
    _animation = CurvedAnimation(
      parent: controller,
      curve: const Interval(0.5, 1.0, curve: Curves.fastOutSlowIn),
    );
  }

  final Widget _view;
  final String _title;
  final BottomNavigationBarItem item;
  final AnimationController controller;
  CurvedAnimation _animation;

  FadeTransition transition(
      BottomNavigationBarType type, BuildContext context) {
  ~~~~~~~~~~~~
  //transition animation setting method
  ~~~~~~~~~~~~
  }
}

这是main.dart
根据用户的操作，将显示列表中的内容。

void main() {
  SystemChrome
      .setPreferredOrientations([DeviceOrientation.portraitUp]).then((_) {
    runApp(MyApp());
  });
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: RootTabView(), 
    );
  }
}

class RootTabView extends StatefulWidget {
  @override
  _RootTabViewState createState() => _RootTabViewState();
}

class _RootTabViewState extends State<RootTabView>
    with TickerProviderStateMixin {
  int _currentIndex = 0;
  BottomNavigationBarType _type = BottomNavigationBarType.fixed;
  List<TabItem> _tabItems;

  @override
  void initState() {
    super.initState();
    // tabitems of view
    _tabItems = <TabItem>[
      TabItem(
        view: hoge0View(),
        icon: const Icon(Icons.accessibility),
        title: 'hoge0',
        vsync: this,
      ),
      TabItem(
        view: hoge1View(),
        icon: const Icon(Icons.accessibility),
        title: 'hoge1',
        vsync: this,
      ),
      TabItem(
        view: hoge2View(),
        icon: const Icon(Icons.accessibility),
        title: 'hoge2',
        vsync: this,
      ),
      TabItem(
        view: hoge3View(),
        icon: const Icon(Icons.accessibility),
        title: 'hoge3',
        vsync: this,
      )
    ];

    for (TabItem tabItem in _tabItems) {
      tabItem.controller.addListener(_rebuild);
    }

    _tabItems[_currentIndex].controller.value = 1.0;
  }

  @override
  void dispose() {
    for (TabItem tabItem in _tabItems) {
      tabItem.controller.dispose();
    }
    super.dispose();
  }

  void _rebuild() {
    if (this.mounted) {
      setState(() {
        // Rebuild in order to animate views.
      });
    }
  }

  Widget _buildTransitionsStack() {
    final List<FadeTransition> transitions = <FadeTransition>[];

    for (TabItem tabItem in _tabItems) {
      transitions.add(tabItem.transition(_type, context));
    }

    // We want to have the newly animating (fading in) views on top.
    transitions.sort((FadeTransition a, FadeTransition b) {
      final Animation<double> aAnimation = a.opacity;
      final Animation<double> bAnimation = b.opacity;
      final double aValue = aAnimation.value;
      final double bValue = bAnimation.value;
      return aValue.compareTo(bValue);
    });

    return Stack(children: transitions);
  }

  @override
  Widget build(BuildContext context) {
    final BottomNavigationBar botNavBar = BottomNavigationBar(
      items: _tabItems.map((TabItem tabItem) => tabItem.item).toList(),
      currentIndex: _currentIndex,
      type: _type,
      onTap: (int index) {
        setState(() {
          var currentView = _tabItems[_currentIndex];
          currentView.controller.reverse();
          _currentIndex = index;
          currentView = _tabItems[_currentIndex];
          currentView.controller.forward();
        });
      },
    );
    return Scaffold(
      appBar: AppBar(
        title: Text(_tabItems[_currentIndex]._title),
        actions: actions,
      ),
      body: Center(child: _buildTransitionsStack()),
      bottomNavigationBar: botNavBar,
    );
  }
}

好吧，这里我重写了一部分build方法。 我在索引为1的AppBar上放置了一个按钮，并想要点击并调用所显示视图实例的方法。

var actions = <Widget>[];
if (_currentIndex == 1) {
  var editButton = FlatButton(
      child: Text('Edit'),
      onPressed: () {
        // I want to  call hoge1View method...
      });
  actions.add(editButton);
}
return Scaffold(
  appBar: AppBar(
    title: Text(_tabItems[_currentIndex]._title),
    actions: actions,
  ),
  body: Center(child: _buildTransitionsStack()),
  bottomNavigationBar: botNavBar,
);

Hoge1View的实现如下。 我想在点击editButton时调用showEditButtonDialog（）。

class Hoge1View extends StatefulWidget {
  @override
  _Hoge1ViewState createState() => _Hoge1ViewState();
}

class _Hoge1ViewState extends State<DiaryView> {

  Future showEditButtonDialog() async {
    return showDialog(
        context: context,
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('test'),
            content: SingleChildScrollView(
              child: ListBody(
                children: <Widget>[Text('test message')],
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text('action1'),
                onPressed: () {
                  print('pressed');
                },
              )
            ],
          );
        });
  }

  @override

  Widget build(BuildContext context) {

    return ListView(
      children: <Widget>[
        Container(),
        Container(),
        Container(),
      ]
    );
  }
}

我不知道如何获取onPress上当前显示的Hoge1View实例。