How to pass data from one class to another?

[sona]

How to pass myLocation.latitude of class SelectonMap to textfield of FormPage

class SelectOnMap extends StatefulWidget {

  static final String pageName = "selectonmappage";

  Position currentposition;
  SelectOnMap(this.currentposition);

  @override
  State<StatefulWidget> createState() {
    return SelectOnMapState(this.currentposition);
  }

}



class SelectOnMapState extends State<SelectOnMap>
    with TickerProviderStateMixin {

  Position currentposition;
  //String _currentAddress;
  SelectOnMapState(this.currentposition);

  static LatLng myLocation = new LatLng(51.5, -0.09);
  @override
  void initState() {
    super.initState();
    setState(() {
      myLocation;
    });
  }
  @override
  Widget build(BuildContext context) {

    Size screenSize = MediaQuery.of(context).size;


      child: Scaffold(

        body:Container(
          height : MediaQuery.of(context).size.height,
          child:new Directionality(
              textDirection: TextDirection.rtl,
              child: new Container(
                  padding: new EdgeInsets.only(bottom: 0.0, left: 1.0, right: 1.0),
                  color: Colors.white,
                  child: new FlutterMap(
                    options: new MapOptions(
                      center: LatLng(currentposition.latitude,currentposition.longitude),
                       
                        zoom: 15.0,
                        maxZoom: 15.0,
                        minZoom: 3.0,
                        onTap: _handleTap
                    ),
                    layers: [
                      new TileLayerOptions(
                        urlTemplate:
                        "https://{s}.a b c",
                        subdomains: ['a', 'b', 'c'],
                        //tileProvider: NonCachingNetworkTileProvider(),
                      ),
                      new MarkerLayerOptions(
                          markers:[
                            Marker(
                              width: 80.0,
                              height: 80.0,
                              point: myLocation,

                              builder: (ctx) =>
                              new Container(

                                child: IconButton(icon: Icon(Icons.location_on,
                                  color: Colors.green,
                                ), onPressed: null),
                              ),
                            ),
                          ]
                      )
                    ],
                  )
              )
          ),
        ),
        floatingActionButton: FloatingActionButton(
            onPressed: (){ Navigator.push(
                context,
                MaterialPageRoute(
                builder: (context) => FormPage( :myLocation.latitude),
              ));
                  },

          child: Icon(Icons.check),
          backgroundColor: Colors.blue,
        ),

    );
  }
  _handleTap(LatLng point) {
    setState(() {
      myLocation = point;
      print("hello");
      print(myLocation.longitude);
      print(myLocation.latitude);
      //_getAddressFromLatLng();
    });
  }
  void getLocation() async {
    Position position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.low);
    print(position.latitude);
    print("lat");
    print(position.longitude);
  }

  void moveToLastScreen() {
    Navigator.of(context).pop(

    );
  }

}

import 'dart:convert';
import 'location.dart';
import 'package:flutter/material.dart';
import 'InputDeco_design.dart';
import 'package:http/http.dart' as http;

class FormPage extends StatefulWidget {


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

class _FormPageState extends State<FormPage> {


String stopname, platname, platdesc,direction, lat,lng,stop_name;

  //TextController to read text entered in text field
  TextEditingController _stopname = TextEditingController();
  TextEditingController _platname = TextEditingController();
  TextEditingController _platdesc = TextEditingController();
  TextEditingController _direction = TextEditingController();
  TextEditingController _lat = TextEditingController();
  TextEditingController _lng = TextEditingController();

  final GlobalKey<FormState> _formkey = GlobalKey<FormState>();


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SingleChildScrollView(
          child: Form(
            key: _formkey,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                CircleAvatar(
                  radius: 30,
                  backgroundColor: Colors.black,
                  child: Image.asset(
                    'assets/itspe.png', height: 50, width: 45,),
                ),
                SizedBox(
                  height: 15,
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_stopname,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.person, "Stop Name"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please Enter a Stop Name';
                      }
                      return null;
                    },
                    onSaved: (String value) {
                      stopname = value;
                    },
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_platname,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(
                        Icons.email, "Platform Name"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please Enter a Platform Name';
                      }

                      return null;
                    },
                    onSaved: (String value) {
                      platname = value;
                    },
                  ),
                ),

                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_platdesc,
                    keyboardType: TextInputType.number,
                    decoration: buildInputDecoration(
                        Icons.phone, "Platform Description"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please enter a Description ';
                      }
                      return null;
                    },
                    onSaved: (String value) {

                    },
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller: _direction,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.lock, "Towards"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please enter Towards';
                      }
                      return null;
                    },
                    onSaved: (String value) {
                      direction= value;
                    },

                  ),
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(

                    controller: _lat,

                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.lock, "Latitude",),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please enter Latitude';
                      }

                      return null;
                    },
                    onSaved: (String value) {
                      lat = value;
                    },

                  ),
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller: _lng,


                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.lock, "Longitude"),
                    validator: (String value) {

                      if (value.isEmpty) {
                        return 'Please enter Longitude';
                      }


                      return null;
                    },
                    onSaved: (String value) {
                      lng = value;
                    },

                  ),
                ),

                SizedBox(
                  width: 200,
                  height: 50,
                  child: RaisedButton(
                    color: Colors.redAccent,
                    onPressed: () {
                      if (_formkey.currentState.validate()) {
                        RegistrationUser();
                        print("successful");

                        return;
                      } else {
                        print("UnSuccessfull");
                      }
                    },
                    shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(60.0),
                        side: BorderSide(color: Colors.blue, width: 2)
                    ),
                    textColor: Colors.white,
                    child: Text("Submit"),

                  ),
                )
              ],
            ),
          ),
        ),
      ),
    );
  }

[Marijo Mihelčić]

Something like this:

class FormPage extends StatefulWidget {

final LatLng myLocation;

FormPage({Key? key, required this.myLocation   }) : super(key: key);

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

class _FormPageState extends State<FormPage> {

@override
  Widget build(BuildContext context) {

     return Text(widget.myLocation.toString());