I am getting this error "The instance member 'setState' cant be accessed in an initializer". Flutter/Dart - flutter

Question

I am getting this error "The instance member 'setState' cant be accessed in an initializer" here :
This is the full code :
class insertLossEvent extends StatefulWidget {
#override
State<insertLossEvent> createState() => _insertLossEventState();
}
class _insertLossEventState extends State<insertLossEvent> {
static final field_1Controller = TextEditingController();
static final field_4Controller = TextEditingController();
void _sendLogin() async {
var newMessage = await (ReadCache.getString(key: 'cache1'));
var map = <String, dynamic>{
"Field_1": field_1Controller.text,
"Field_4": field_4Controller.text,
"table_id": "25510",
"form_type": "2",
};
var res = await http.post(
Uri.parse("http://192.168.1.4:8080/HongLeong/SET_FORM_REQUEST.do"),
headers: {HttpHeaders.cookieHeader: newMessage},
body: map,
);
final data = jsonDecode(res.body);
print(data);
}
int _selectedIndex = 0;
void _navigateBottomBar(int index) {
setState(() {
_selectedIndex = index;
});
}
static List<String> orgUnit = [
'M1',
'M100138',
'M100078',
'M100108',
'M100069',
'M100118',
'M100071',
'M100150'
];
static String valueChoose;
final List<Widget> _pages = [
Container(
child: SingleChildScrollView(
child: Column(
children: [
//Main Info
ListTileTheme(
tileColor: Colors.grey,
child: ExpansionTile(
title: Text('Main Info',
style: GoogleFonts.poppins(
textStyle: const TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 20,
))),
children: [
//Fields
ListTileTheme(
tileColor: Colors.white,
child: ListTile(
title: Text(
'Title : ',
style: GoogleFonts.poppins(
textStyle: const TextStyle(
fontWeight: FontWeight.bold,
fontSize: 20,
),
),
),
),
),
ListTileTheme(
tileColor: Colors.white,
child: ListTile(
title: Container(
decoration: BoxDecoration(
color: Colors.transparent,
border: Border.all(color: Colors.blueGrey),
borderRadius: BorderRadius.circular(10),
),
child: Padding(
padding: const EdgeInsets.all(8.0),
child: TextField(
decoration: InputDecoration(
border: InputBorder.none,
),
controller: field_1Controller,
style: GoogleFonts.poppins(
textStyle: const TextStyle(
fontWeight: FontWeight.normal,
fontSize: 20,
),
),
),
),
),
),
),
ListTileTheme(
tileColor: Colors.white,
child: ListTile(
title: Text(
'Organization Unit : ',
style: GoogleFonts.poppins(
textStyle: const TextStyle(
fontWeight: FontWeight.bold,
fontSize: 20,
),
),
),
),
),
ListTileTheme(
tileColor: Colors.white,
child: ListTile(
title: Container(
decoration: BoxDecoration(
color: Colors.transparent,
border: Border.all(color: Colors.blueGrey),
borderRadius: BorderRadius.circular(10),
),
child: Padding(
padding: const EdgeInsets.all(8.0),
child: DropdownButton<String>(
value: valueChoose,
onChanged: (newValue){
setState(() {
valueChoose = newValue;
});
},
items: orgUnit.map((valueItem) {
return DropdownMenuItem(
value: valueItem,
child: Text(valueItem),
);
}).toList(),
),
),
),
),
),
],
),
),
],
),
),
),
Container(
child: SingleChildScrollView(
child: Column(
children: [
//Shariah Details
ListTileTheme(
tileColor: Colors.grey,
child: ExpansionTile(
title: Text('Shariah Details',
style: GoogleFonts.poppins(
textStyle: const TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 20,
))),
children: [
//Fields
],
),
),
],
),
),
)
];
In the best case scenario, I'd like to retain the code as this, but if you know of any improvements, please let me know.
How can I make it better? & what causes it to take place?
Thank You

Answer 1

to solve the problem, just add the pages List in the build Function and add return Container();
#override
Widget build(BuildContext context) {
final List<Widget> _pages = [
....
];
return Container();
}

Answer 2

Define pages like
List<Widget> _pages = [];
Then in initstate add values to it
_pages = [// add values here
];
setState((){});
The issue is that you tried adding set state when the codes are initialising. Adding it in initatate will not theow this error

Answer 3

Using late keyword will fix this issue like
late final List<Widget> _pages = [
But I will suggest to use method instead of variables in this case. Using variable doesn't get update context until you reassign the variable.
Do like this is better
List<Widget> _pages(BuildContext context) => [