How to set state after dispose() in flutter? - flutter

Question

I have 2 pages, in the first page I have a button which is on click will open second page, in second page I have variable number = 999; so when I back to the first page I want to show the number print(number); or display on Text(number) How to do it with dispose() ?
#override
void dispose() {
super.dispose();
// send data to the first page
}
thanks for your answer

Answer 1

You can simply do this with the help of a navigator.
Navigator.push returns a Future that completes after calling
Navigator.pop on the Second Screen with the value passed.
e.x code:
import 'package:flutter/material.dart';
void main() {
runApp(MaterialApp(
title: 'Returning Data',
home: HomeScreen(),
));
}
class HomeScreen extends StatelessWidget {
String _resultNumber = '';
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Returning Data Demo'),
),
body: Center(child: SelectionButton()),
);
}
}
class SelectionButton extends StatefulWidget {
#override
_SelectionButtonState createState() => _SelectionButtonState();
}
class _SelectionButtonState extends State<SelectionButton> {
String _resultNumber;
#override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(
onPressed: () => _navigateAndDisplaySelection(context),
child: Text('Pick an option, any number!'),
),
Text(_resultNumber ?? ''),
]);
}
_navigateAndDisplaySelection(BuildContext context) async {
// Navigator.push returns a Future that completes after calling
// Navigator.pop on the Selection Screen.
final result = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => SelectionScreen()),
);
_resultNumber = result;
}
}
class SelectionScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Pick a number'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: RaisedButton(
onPressed: () {
// Close the screen and return "Yep!" as the result.
Navigator.pop(context, '999');
},
child: Text('999 Number'),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: RaisedButton(
onPressed: () {
// Close the screen and return "Nope!" as the result.
Navigator.pop(context, '500');
},
child: Text('550 Number'),
),
)
],
),
),
);
}
}

Answer 2

With dispose() you need override the back pressed, to do this wrap the Scaffold in WillPopScope widget.
return WillPopScope(
onWillPop: () {
_backPressed();
return Future.value(false);
},
child: Scaffold(
appBar: AppBar(
title: Text('your text'),
),
body: Center(),
),
);
void _backPressed() {
Navigator.pop(context, '999');
}