Question

我试图通过访问状态类的方法来查看另一个类的文本字段数据。单击按钮时，我想在另一个类中获取文本字段值。

我尝试调用应该返回字符串的方法，但是当我尝试从另一个类访问它时却没有任何值。

class TitleWidget extends StatefulWidget{
  final IncidentComponent data;
  String titleVal;
  TitleWidget(this.data);
  @override
  TitleWidgetState createState() => TitleWidgetState();
}

class TitleWidgetState extends State<TitleWidget>{

  final titleController = TextEditingController();

  titleTextValue() {
    print("title text field: ${titleController.text}");
    return titleController.text;
  }

  @override
  void initState() {
    super.initState();
    titleController.addListener(titleTextValue);
  }

  @override
  Widget build(BuildContext context) {
    return  TextField(
      controller: titleController);

  }
}

我试图访问上述方法以在另一个类中获取字符串。

FloatingActionButton.extended(
   label: Text("Complete Report",
   onPressed: () { print('title is ' + TitleWidgetState().titleTextValue()); }
)

当我按下另一个班级的FAB按钮时，我一直期望文本字段值。但是我从其他类方法中什么也没得到。但是titleTextValue（）方法的print语句将打印正确的文本字段值。

Answer 1

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import 'package:flutter_web/material.dart';
import 'package:flutter_web/widgets.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        body: new Column(
          mainAxisAlignment: MainAxisAlignment.spaceAround,
          children: <Widget>[
            new MyStatefulWidget1(),
            new MyStatefulWidget2(),
          ],
        ),
      ),
    );
  }
}

class MyStatefulWidget1 extends StatefulWidget {
  State createState() => new MyStatefulWidget1State();
}

class MyStatefulWidget1State extends State<MyStatefulWidget1> {
  final titleController = TextEditingController();

  titleTextValue() {
    print("title text field: ${titleController.text}");
    return titleController.text;
  }

  @override
  Widget build(BuildContext context) {
    store.set("titleTextValue", titleTextValue);
    return TextField(controller: titleController);
  }
}

class MyStatefulWidget2 extends StatefulWidget {
  State createState() => new MyStatefulWidget2State();
}

class MyStatefulWidget2State extends State<MyStatefulWidget2> {
  String _text = 'PRESS ME';

  @override
  Widget build(BuildContext context) {
    var titleTextValue = store.get("titleTextValue");
    return new Center(
      child: new RaisedButton(
          child: new Text(_text),
          onPressed: () {
            print('title is ' + titleTextValue());
          }),
    );
  }
}

class GlobalState {
  final Map<dynamic, dynamic> _data = <dynamic, dynamic>{};

  static GlobalState instance = GlobalState._();
  GlobalState._();

  set(dynamic key, dynamic value) => _data[key] = value;
  get(dynamic key) => _data[key];
}

final GlobalState store = GlobalState.instance;

从另一个有状态小部件类中获取文本字段数据

1 个答案: