如何通过按下按钮从另一个类更新地图

Question

我在屏幕上有一些基于地图内容动态呈现的小部件。我已经通过一个文本字段更新了地图的内容，并且它一直运行良好，直到我决定将此文本字段移动到一个单独的类/屏幕。如何从这个单独的屏幕正确调用 setState 并在我返回时反映我的更新？

顺便说一句，我花了很多时间试图研究这个问题，但除了可能需要使用回调函数之外，我似乎无法解决任何问题？

NoteSection 是从提醒地图动态呈现的

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

final Map<String, String> reminders = {};

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Note App'),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => AddNoteScreen(),
            ),
          );
        },
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          NoteSection(),
        ],
      ),
    );
  }
}

我正在更新地图的屏幕代码如下

class AddNoteScreen extends StatefulWidget {
  @override
  _AddNoteScreenState createState() => _AddNoteScreenState();
}

final titleController = TextEditingController();
final bodyController = TextEditingController();

String noteBodyText = bodyController.text;
String noteTitleText = titleController.text;

class _AddNoteScreenState extends State<AddNoteScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Note App'),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          titleTextField,
          bodyTextField,
          Container(
            padding: EdgeInsets.only(
              right: 10,
              bottom: 10,
            ),
            child: ElevatedButton(
              style: ElevatedButton.styleFrom(
                primary: Colors.amber,
              ),
              child: Text(
                'Add Note',
                style: TextStyle(color: Colors.white),
              ),
              onPressed: () {
                setState(() {
                  noteTitleText = titleController.text;
                  noteBodyText = bodyController.text;
                  reminders[noteTitleText] = noteBodyText;
                  titleController.clear();
                  bodyController.clear();
                  Navigator.pop(context);
                });
              },
            ),
          ),
        ],
      ),
    );
  }
}

Answer 1

这行得通

class MyHomePage extends StatefulWidget {
      @override
      _MyHomePageState createState() => _MyHomePageState();
    }
    
    final Map<String, String> reminders = {};
    List<String> _information = [];
    
    class _MyHomePageState extends State<MyHomePage> {
   

        void updateInformation(List<String> information) {
        setState(() => reminders[information[0]] = information[1]);
      }
    void moveToSecondPage() async {
        List<String> information = await Navigator.push(
          context,
          MaterialPageRoute(
              fullscreenDialog: true, builder: (context) => AddNoteScreen()),
        );
        updateInformation(information);
       
      }
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: Text('Note App'),
          ),
          floatingActionButton: FloatingActionButton(
            child: Icon(Icons.add),
            onPressed: () {
               moveToSecondPage();
            },
          ),
          body: Column(
            crossAxisAlignment: CrossAxisAlignment.end,
            children: [
              NoteSection(),
            ],
          ),
        );
      }
    }

添加笔记屏幕

class AddNoteScreen extends StatefulWidget {
  @override
  _AddNoteScreenState createState() => _AddNoteScreenState();
}

final titleController = TextEditingController();
final bodyController = TextEditingController();

String noteBodyText = bodyController.text;
String noteTitleText = titleController.text;

class _AddNoteScreenState extends State<AddNoteScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Note App'),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          titleTextField,
          bodyTextField,
          Container(
            padding: EdgeInsets.only(
              right: 10,
              bottom: 10,
            ),
            child: ElevatedButton(
              style: ElevatedButton.styleFrom(
                primary: Colors.amber,
              ),
              child: Text(
                'Add Note',
                style: TextStyle(color: Colors.white),
              ),
              onPressed: () {
               
                  noteTitleText = titleController.text;
                  noteBodyText = bodyController.text;
                 
                  Navigator.pop(context,[noteTitleText,noteBodyText]);
                
              },
            ),
          ),
        ],
      ),
    );
  }
}

了解更多请访问passing data when popping view in flutter

Answer 2

您应该通过构造函数将 noteBodyText 传递给 myhomepage statefull 小部件，以便您的 myHomePage 看起来像这样

class MyHomePage extends StatefulWidget {
String noteBodyText;
MyHomePage({this.noteBodyText});
  
  @override
  _MyHomePageState createState() => _MyHomePageState();
}


final Map<String, String> reminders = {};

class _MyHomePageState extends State<MyHomePage> {
void initState(){
  reminders[noteTitleText] = widget.noteBodyText;
}

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Note App'),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => AddNoteScreen(),
            ),
          );
        },
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          NoteSection(),
        ],
      ),
    );
  

}
}

addnotescreen 应该是这样的

class AddNoteScreen extends StatefulWidget {
  @override
  _AddNoteScreenState createState() => _AddNoteScreenState();
}

final titleController = TextEditingController();
final bodyController = TextEditingController();

String noteBodyText = bodyController.text;
String noteTitleText = titleController.text;

class _AddNoteScreenState extends State<AddNoteScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Note App'),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          titleTextField,
          bodyTextField,
          Container(
            padding: EdgeInsets.only(
              right: 10,
              bottom: 10,
            ),
            child: ElevatedButton(
              style: ElevatedButton.styleFrom(
                primary: Colors.amber,
              ),
              child: Text(
                'Add Note',
                style: TextStyle(color: Colors.white),
              ),
              onPressed: () {
                
                  noteTitleText = titleController.text;
                  noteBodyText = bodyController.text;
                  
                  
                  Navigator.push(
        context,
        MaterialPageRoute(
          builder: (context) => MyHomePage(noteBodyText:noteBodyText),
        ),
      );
               
              },
            ),
          ),
        ],
      ),
    );
  }
}