问Flutter form -多屏幕

EN

class FirstFormPage extends StatefulWidget {
  @override
  _FirstFormPageState createState() => _FirstFormPageState();
}

class _FirstFormPageState extends State<FirstFormPage> {
  TextEditingController _firstFormFieldController = TextEditingController();
  TextEditingController _secondFormFieldController = TextEditingController();
  TextEditingController _thirdFormFieldController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        TextFormField(
          controller: _firstFormFieldController,
        ),
        TextFormField(
          controller: _secondFormFieldController,
        ),
        TextFormField(
          controller: _thirdFormFieldController,
        ),
        RaisedButton(
          child: Text('Next'),
          onPressed: () => Navigator.of(context).push(MaterialPageRoute(
            builder: (context) {
              return SecondFormPage([
                _firstFormFieldController.text,
                _secondFormFieldController.text,
                _thirdFormFieldController.text,
              ]);
            }
          )),
        )
      ],
    );
  }
}

class SecondFormPage extends StatefulWidget {
  final List<String> previousFields;

  SecondFormPage(this.previousFields);

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

class _SecondFormPageState extends State<SecondFormPage> {
  TextEditingController _firstFormFieldController = TextEditingController();
  TextEditingController _secondFormFieldController = TextEditingController();
  TextEditingController _thirdFormFieldController = TextEditingController();

  List<String> allData = [];

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        TextFormField(
          controller: _firstFormFieldController,
        ),
        TextFormField(
          controller: _secondFormFieldController,
        ),
        TextFormField(
          controller: _thirdFormFieldController,
        ),
        RaisedButton(
          child: Text('Next'),
          onPressed: submitData,
        )
      ],
    );
  }

  void submitData(){
    allData.addAll(widget.previousFields);
    allData.addAll([
      _firstFormFieldController.text,
      _secondFormFieldController.text,
      _thirdFormFieldController.text,
    ]);

    // Submit your data
  }
}