flutter radiobutton widget refresh after click - windows

Question

I'm building a flutter app for windows. I've made a screen where a list of programmaticly generated Radio Widgets (about 40 radiogroups with 2 or 3 radio widgets in each group) is shown. Everything works when clicked. The value is updated, yet the radiobuttons do not change it's appearance (it does not show it's selected), this is until I scroll the radiogroup out of sight and scroll it back into sight (probably because it is rebuilt at that moment).
Any hints?
---update
Sorry for not posting any code at first, the problem I've described did not seem the kind of problem that would need so.
There are many issues and solutions on here that go on about refreshing
So far this is the one that makes it work.
setState(() {
FutureToBeRefreshed = functionToGetData;
}
There's only one drawback. After setState, the whole screen gets refreshed and starts at the first position, which is annoying when you changed the value of a radiobutton which is offscreen at the beginning.
I'm not that experienced (let's say I've just started with flutter) and any solutions involving scrollControllers and .jumpTo the scrollposition I could not get to work.
For now, I've came up with a solution that involves paging so that there are no elements outside the visible Viewport. Yet if there's a different solution other than paging, please let me know.
#override
initState() {
super.initState();
Size size = WidgetsBinding.instance.window.physicalSize;
screenWidth = size.width;
screenHeight = size.height;
pageIndex = 0;
headerHeight = 330;
lineHeight = 70;
if (screenHeight == null || screenHeight < (headerHeight + 2*lineHeight) ) {
screenHeight = (headerHeight + 2*lineHeight);
}
double tmpCalc = (screenHeight - headerHeight ) / lineHeight ;
maxLines = tmpCalc.toInt();
datafields = getDataFields();
}

Answer 1

There is no need for paging if you use a ListView instead of a Viewport.
About the refresh, you should definitely use setState to at least store the selected Radio buttons.
Check this screen recording below of a prototype and the live demo on DartPad. Is this what you're expecting?
Here's the prototype code:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(),
debugShowCheckedModeBanner: false,
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key}) : super(key: key);
#override
State<MyHomePage> createState() => _MyHomePageState();
}
final groups = [
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2],
[1, 2],
[1, 2],
[1, 2],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
[1, 2],
[1, 2],
[1, 2, 3],
[1, 2, 3],
[1, 2, 3],
[1, 2],
].asMap();
class _MyHomePageState extends State<MyHomePage> {
final selectedRadiosByGroup = <int, int>{};
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Expanded(
child: ListView.separated(
itemCount: groups.length,
separatorBuilder: (context, _) => const Divider(
height: 2,
),
itemBuilder: ((context, groupIndex) {
final group = groups[groupIndex]!;
return Row(
children: [
for (final entry in group)
Row(
children: [
Radio(
value: entry,
groupValue: selectedRadiosByGroup[groupIndex],
onChanged: (value) => setState(
() => selectedRadiosByGroup[groupIndex] = entry),
),
Text('$groupIndex:$entry'),
],
)
],
);
}),
),
),
),
);
}
}