Calling setState() from another page - Flutter - flutter

Question

I have a String _value, which I would like to call it from another page.
Here is my players.dart
class MyWidgetPopup extends StatefulWidget {
#override
MyWidgetPopupState createState() => MyWidgetPopupState();
}
enum Answers{FIRST,SECOND}
class MyWidgetPopupState extends State<MyWidgetPopup> {
String _value = '';
void _setValue(String value) => setState(() => _value = value);
Future selectGk(BuildContext context) async {
switch(
await showDialog(
...
...
{
case Answers.FIRST:
_setValue('FIRST TEAM');
break;
case Answers.SECOND:
_setValue('SECOND TEAM');
break;
}
}
So, in players.dart, I can show the selected team with simple code: Text(_value)
But I would like to show it in select.dart
import 'package:flutter/material.dart';
import 'package:myapp/players.dart';
MyWidgetPopupState dataSource = MyWidgetPopupState();
class Besdortbir extends StatefulWidget {
#override
_BesdortbirState createState() => _BesdortbirState();
}
class _BesdortbirState extends State<Besdortbir> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(
'My Title'),
centerTitle: true,
backgroundColor: Colors.redAccent[700],
elevation: 0.0,
),
body: Stack(
fit: StackFit.expand,
children: <Widget>[
Container(
decoration: BoxDecoration(
image: new DecorationImage(
image: new AssetImage("assets/field.png"),
fit: BoxFit.fill
)
),
),
//FIRST PLAYER
Container(
padding: EdgeInsets.only(bottom: 90.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
GestureDetector(
onTap: (){dataSource.selectGk(context);}, //I have the FIRST TEAM and SECOND TEAM listed here.
child: Container(
child: ClipRRect(
borderRadius: BorderRadius.circular(20.0),
child: Image.asset('assets/PLUS.png',
scale: 8),
),
),
),
Text(//somehow I would like to show which team is selected by user),
],
),
),
],
),
);
}
}
I have tried to recall setState(), _value, and a few other options. But, I could not be successful.