How to create a Checkbox and access global variable from class? - flutter

Question

I am trying to create a checkbox inside my view. I declared bool variable isChecked= false in my state class, and while writing constructor for checkbox getting the error on my isChecked variable as 'Only static members can be accessed in intializers'. I made the variable as static, which removed the error on bool variable, but giving the same error on setState(). How do i resolve this ?
import 'package:flutter/material.dart';
class CardScreen extends StatelessWidget{
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Card Screen',
home: new myPetScreen()
);
}
}
class myPetScreen extends StatefulWidget{
myPetScreen({Key key, this.title}) : super(key: key);
final String title;
#override
_myPetScreenState createState() => new _myPetScreenState();
}
class _myPetScreenState extends State<myPetScreen>{
static bool isChecked = false;
final view = new Column(
children: <Widget>[
//did other UI Implementation here
Container(
child: Flexible(
child: ListView.builder(itemBuilder: (context, position){
return Card(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Row(
children: <Widget>[
Text(position.toString(), style: TextStyle(fontSize: 14.0, color: Colors.black),),
Spacer(),
Checkbox(
value: isChecked,
onChanged: (value) {
setState(() {
isChecked = value;
});
},
),
],
),
)
);
}
),
),
) ,
],
);
#override Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Card Screen')),
body: view,
);
}
}

Answer 1

make some change take your column code into one method then that method called into widget..
like this way..
Column getView(){
var view = new Column(
children: <Widget>[
//did other UI Implementation here
Container(
child: Flexible(
child: ListView.builder(itemBuilder: (context, position) {
return Card(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Row(
children: <Widget>[
Text(
position.toString(),
style: TextStyle(fontSize: 14.0, color: Colors.black),
),
Spacer(),
Checkbox(
value: isChecked,
onChanged: (value) {
changeState(value);
},
),
],
),
));
}),
),
),
],
);
return view;
}
after that called this way..
body: getView()

Answer 2

You are declaring view as a final variable, so it is immutable. change it to a function like so:
Widget get view => Container(
//...
)
Also, don't forget to remove static from the state declaration (Never do that in a stateful wiget).