Flutter:How to update a UI -stateful widget from another stateful class - flutter

Question

How do I update my UI when the value change in another stateful widget?.
I created a stateful class (Test2) which build a widget. Then in my main class, I have a list of Test2 widget. Finally, I am iterating thru the list and rendering the Test2 widget.
However, I want to update a value in one of Test2 widget and then have the main UI update accordingly.
How can I do that?
FILE:test2.dart
class Test2 extends StatefulWidget {
Test2({this.responseId, this.message});
final String responseId;
final String message;
bool strike =false;
#override
_Test2State createState() => _Test2State();
}
class _Test2State extends State<Test2> {
#override
Widget build(BuildContext context) {
return Container(
child: Text(
widget.responseId + widget.message,
style: (widget.strike)?TextStyle(decoration: TextDecoration.none):TextStyle(decoration: TextDecoration.underline)
),
);
}
}
File :home.dart
MAIN CLASS
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<Test2> _counter =List();
int cnt =0;
#override
void initState() {
super.initState();
_counter.add(Test2(message: "message",responseId:"1"));
_counter.add(Test2(message: "message",responseId:"2"));
_counter.add(Test2(message: "message",responseId:"3"));
}
In my BUILD METHOD
for(int i=0;i<_counter.length;i++)...[
_counter[i]
],
BUTTON CLICK
void _incrementCounter() {
for(int i=0;i<_counter.length;i++){
if(_counter[i].responseId =="1"){
_counter[i].strike =true;
}
}
setState(() {
});
}

Answer 1

You can use ValueNotifier to rebuild the listeners.
Decalre a ValueNotifier<bool> in the Text2 class and initialize it.
ValueNotifier<bool> strikeNotifier = ValueNotifier(false);
then use ValueListenableBuilder to wrap the widget that you want to rebuild when value of strike changes.
ValueListenableBuilder(valueListenable: strikeNotifier, builder: (_, result, widget) => Text(...),)
And create a method for updating the value of strike, also for comparing the old and new values and update the value of ValueNotifier with the comparison result.
void updateStrike(bool value){
var result = (strike == value);
strike = value;
strikeNotifier.value = result;
}
So you can update the value of strike with updateStrike() in _incrementCounter() to notify the Text2 widgets for rebuilding.