How to send setState to Second Page in Flutter? - flutter

Question

I have a basic question about send setState
to Second Page in the same class as this method like
_GoToNextPage(){
Navigator.of(context).push(MaterialPageRoute(builder: (context) {...})
}
The problem is when I change background color in second page it doesn't
change color in the same page But it changes the color of The prime home page.
This is the full code...
import 'package:flutter/material.dart';
void main() => runApp(MaterialApp(
home: SetStateToSecondPage(),
));
class SetStateToSecondPage extends StatefulWidget {
#override
_SetStateToSecondPageState createState() => _SetStateToSecondPageState();
}
class _SetStateToSecondPageState extends State<SetStateToSecondPage> {
Color color = Colors.deepPurpleAccent;
bool Switch = false;
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: color,
appBar: AppBar(
title: Text('setState to Second Page ?'),
elevation: 0.0,
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
RaisedButton(
onPressed: () {
setState(() {
Switch = !Switch;
color = Switch ? Colors.white : Colors.green;
});
},
child: Text('Change Back GroundColor'),
),
RaisedButton(
onPressed: () {
_GoToNextPage(context);
},
child: Text('To Next Page..'),
),
],
),
),
);
}
//------------- This is second Page ----------//
_GoToNextPage(BuildContext context) {
return Navigator.of(context).push(MaterialPageRoute(builder: (context) {
return Scaffold(
appBar: AppBar(
title: Text('Second Page'),
),
backgroundColor: color,
body: Center(
child: RaisedButton(
onPressed: () {
setState(() {
color = Colors.red;
});
},
child: Text('Change Back GroundColor'),
),
),
);
}));
}
}
thanks

Answer 1

SetState is specific to the object you are in . and when you call it you notify the framework that the state has changed . so calling setState in _SetStateToSecondPageState will not affect Second Page so you need to create another StatefulWidget
class SecondPage extends StatefulWidget {
MaterialColor secondColor ;
SecondPage({this.secondColor});
#override
_SecondPageState createState() => new _SecondPageState();
}
class _SecondPageState extends State<SecondPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Second Page'),
),
backgroundColor: widget.secondColor,
body: Center(
child: RaisedButton(
onPressed: () {
setState(() {
widget.secondColor = Colors.amber;
});
},
child: Text('Change Back GroundColor'),
),
),
);
}
}
and when you call _GoToNextPage use the SecondPage constructor to change the color
_GoToNextPage(BuildContext context) {
return Navigator.of(context).push(MaterialPageRoute(builder: (context) {
return SecondPage(
);
}));
}