How to set a variable value in a widget and in another widget? - flutter

Question

I'm trying to set a variable value (number, in the code below) that exists in FirstWidget, from SecondWidget. And notify both widgets so the number will be updated in the two widgets.
class FirstWidget extends StatefulWidget {
#override
_FirstWidgetState createState() => _FirstWidgetState();
}
class _FirstWidgetState extends State<FirstWidget> {
int number = 0;
#override
Widget build(BuildContext context) {
return Column(
children: [
Text(
'$number',
),
SecondWidget(),
Text(
'$number',
)
],
);
}
}
class SecondWidget extends StatefulWidget {
#override
_SecondWidgetState createState() => _SecondWidgetState();
}
class _SecondWidgetState extends State<SecondWidget> {
#override
Widget build(BuildContext context) {
return TextButton(
child: Text('The number is $number. Press to increase the number'),
onPressed: () {
setState(() {
number++;
});
},
);
}
}
(I know that that code gives an error, but the main idea was to give you the problem I want to solve).
The output I want it to be shown:
before pressing the button -
0
The number is 0. Press to increase the number
0
after pressing the button -
1
The number is 1. Press to increase the number
1
So I would be happy if you can help solving this.
Thanks.

Answer 1

There are many approaches to get the result you are looking for, this one is using ValueNotifier in order to change the value of number
Here is an example based on your code:
https://dartpad.dev/b6409e10de32b280b8938aa75364fa7b
We can use another State Management like Provider or Cubit, and we will get the same result.
Another way is to pass a function as a param in the second widget and execute that function when button is pressed