无法在另一个有状态的小部件类flutter中获取有状态小部件类的数据

Question

我无法将我的MapsClass(一个UI屏幕(的任何数据类型获取到AddData类(也是一个UI页面(中。我从DataPush类中获取数据，这是一个简单的类。但我想从MapsClass获得位置值，我正在MapsClass屏幕的初始状态上更新该值。

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:geocoding/geocoding.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:geolocator/geolocator.dart';
import 'AddData.dart';
class MapsClass extends StatefulWidget {
@override
State<StatefulWidget> createState() => _MapState();
}
class _MapState extends State<MapsClass> {
Position curLoc;                    **I want this**
bool mapToggle = false;
GoogleMapController mapController;
List<Placemark> placemarks;
double sliderVal = 0;
String loca;
String country;
void initState() {
super.initState();
Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.best)
.then((curL) => {
setState(() {
curLoc = curL;
mapToggle = true;
this.getAdd();
}),
});
}
getAdd() async {
placemarks =
await placemarkFromCoordinates(curLoc.latitude, curLoc.longitude);
this.country = placemarks.first.country;
this.loca = placemarks.first.locality;
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: <Widget>[
Container(
child: mapToggle
? GoogleMap(
initialCameraPosition: CameraPosition(
target: LatLng(curLoc.latitude, curLoc.longitude),
zoom: 15.0),
myLocationEnabled: true,
onMapCreated: onCreate,
mapType: MapType.normal,
compassEnabled: false,
zoomControlsEnabled: false,
zoomGesturesEnabled: true,
)
: Center(
child: Text(
'Getting Location Please Wait.....',
style: TextStyle(fontSize: 20.0),
),
)),
Positioned(
bottom: 40,
left: 10,
child: FloatingActionButton(
backgroundColor: Colors.green,
child: const Icon(Icons.create),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => AddData()),
);
},
),
),
Align(
alignment: Alignment.topCenter,
child: SizedBox(
width: 200.0,
height: 120.0,
child: Card(
color: Colors.green,
child: Center(
child: Text(
"You are at $loca, $country",
style: TextStyle(color: Colors.white),
), //Text
), //Center
), //Card
),
),
Positioned(
bottom: 40,
left: 70,
child: Slider(
activeColor: Colors.green,
value: sliderVal,
min: 0,
max: 10.0,
divisions: 2,
label: sliderVal.round().toString(),
onChanged: (double value) {
setState(() {
sliderVal = value;
});
},
),
),
],
),
);
}
void onCreate(GoogleMapController controller) {
setState(() {
mapController = controller;
});
}
}

这是我遇到错误的地方，无法获得作为位置数据类型的curLoc的值。我无法从该类中获取任何值。

import 'package:donation_yoga/screens/maps.dart';
import 'package:donation_yoga/services/Submitform.dart';
import 'package:flutter/material.dart';
void main() {
runApp(MaterialApp(
home: AddData(),
));
}
class AddData extends StatefulWidget {
@override
_AddData createState() => _AddData();
}
class _AddData extends State<AddData> {
final _formKey = GlobalKey<FormState>();
final _user = DataPush();
final ma = MapsClass();
var position = ma.curLOC;     // THIS IS WHERE I CAN'T GET ANYTHING OR ANYWHERE in the Entire class**

void initState() {
super.initState();

}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('ADD YOUR CENTER')),
body: Container(
padding:
const EdgeInsets.symmetric(vertical: 16.0, horizontal: 10.0),
child: Builder(
builder: (context) => Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [
TextFormField(
decoration:
InputDecoration(labelText: "Enter Text"),
validator: (value) {
if (value.isEmpty) {
return 'Please Enter Something !!!';
}
return null;
},
onSaved: (val) =>
setState(() => _user.firstName = val),
),
Container(
padding: const EdgeInsets.fromLTRB(0, 50, 0, 20),
child: Text('Options'),
),
CheckboxListTile(
title: const Text('Dry'),
value: _user.passions[DataPush.Dry],
onChanged: (val) {
setState(
() => _user.passions[DataPush.Dry] = val);
}),
CheckboxListTile(
title: const Text('Spot'),
value: _user.passions[DataPush.Spot],
onChanged: (val) {
setState(
() => _user.passions[DataPush.Spot] = val);
}),
CheckboxListTile(
title: const Text('Red'),
value: _user.passions[DataPush.Red],
onChanged: (val) {
setState(
() => _user.passions[DataPush.Red] = val);
}),
CheckboxListTile(
title: const Text('Stretch'),
value: _user.passions[DataPush.Strech],
onChanged: (val) {
setState(() =>
_user.passions[DataPush.Strech] = val);
}),
CheckboxListTile(
title: const Text('Thick'),
value: _user.passions[DataPush.Thick],
onChanged: (val) {
setState(
() => _user.passions[DataPush.Thick] = val);
}),
Container(
padding: const EdgeInsets.symmetric(
vertical: 16.0, horizontal: 16.0),
// ignore: deprecated_member_use
child: RaisedButton(
onPressed: () {
final form = _formKey.currentState;
if (form.validate()) {
form.save();
_user.makePostRequest();
_showDialog(context);
}
},
child: Text('Save'))),
])))));
}
_showDialog(BuildContext context) {
Scaffold.of(context)
// ignore: deprecated_member_use
.showSnackBar(SnackBar(content: Text('Submitting form')));
}
}

Answer 1

@artistAhmed您没有正确传递数据。使用构造函数并传递数据，这样您就可以在另一个屏幕上获得数据。请参阅此flutter文档资源以了解专业知识。这肯定会奏效。如果你还有什么问题，请告诉我。

将数据发送到新屏幕