how to send Data to other screen? - flutter

Question

import 'package:flutter/material.dart';
import 'package:flutter_bmi_app/second_screen.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
class BmiCalc extends StatefulWidget {
const BmiCalc({Key? key}) : super(key: key);
#override
State<BmiCalc> createState() => _BmiCalcState();
}
class _BmiCalcState extends State<BmiCalc> {
Color colorOfLittleBox = Color.fromARGB(255, 27, 28, 48);
Color colorOfLittleBox2 = Colors.pink;
bool isMale = true;
double _value = 150;
int weight = 60;
int age = 25;
double answer = 10;
String calc = "CALCULATE";
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Color.fromARGB(255, 12, 9, 34),
body: SafeArea(
child: SingleChildScrollView(
child: Column(
children: [
Row(
children: [
FemaleBox("MALE", Icons.male),
FemaleBox("FEMALE", Icons.female),
],
),
Column(children: [
Container(
padding: EdgeInsets.all(32),
margin: EdgeInsets.all(10),
decoration: BoxDecoration(
color: Color.fromARGB(255, 27, 28, 48),
borderRadius: BorderRadius.circular(15),
),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
const Text("HEIGHT",
style: TextStyle(color: Colors.grey, fontSize: 20)),
const SizedBox(
height: 10,
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(_value.toStringAsFixed(0),
style: const TextStyle(
fontSize: 45,
color: Colors.white,
fontWeight: FontWeight.w900)),
const Text(
"cm",
style:
TextStyle(fontSize: 20, color: Colors.grey),
),
],
),
Slider(
min: 100,
max: 230,
thumbColor: Colors.pink,
value: _value,
onChanged: (value) {
setState(() {
_value = value;
});
},
),
],
))
]),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Operation("Weight"),
Operation("Age"),
],
),
Container(
decoration: BoxDecoration(
color: Colors.pink,
borderRadius: BorderRadius.circular(15),
),
padding: EdgeInsets.only(bottom: 5),
width: MediaQuery.of(context).size.width,
child: TextButton(
child: Text(
calc,
style: const TextStyle(
fontSize: 22,
color: Colors.white,
fontWeight: FontWeight.w900),
),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondScreen()),
);
},
),
)
],
),
),
),
);
}
void calculate() {
answer = (weight / (_value * _value)) * 10000;
Text(answer.toString(),
style: const TextStyle(fontSize: 40, color: Colors.white));
if (calc == "CALCULATE") {
calc = answer.toStringAsFixed(1);
} else {
calc = "CALCULATE";
}
setState(() {});
}
}
I made bmi calculator, I wanna have answer on other screen. I want to send this function calculate() to the second screen, where I will
have the answer of this calculation. I gave Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondScreen()), but how to make it work? Thank you in advance.

Answer 1

Make the SecondScreen constructor take a parameter for the type of data that you want to send to it.
const SecondScreen(
{Key? key,required this.answer, })
: super(key: key);
final String? answer; //define value you want to pass
#override
_SecondScreenScreenState createState() => _SecondScreenState();
}
And pass data when navigate
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SecondScreen(answer: 'Hello',),
));

Answer 2

here is the example:
import 'package:flutter/material.dart';
class Todo {
final String title;
final String description;
const Todo(this.title, this.description);
}
void main() {
runApp(
MaterialApp(
title: 'Passing Data',
home: TodosScreen(
todos: List.generate(
20,
(i) => Todo(
'Todo $i',
'A description of what needs to be done for Todo $i',
),
),
),
),
);
}
class TodosScreen extends StatelessWidget {
const TodosScreen({Key? key, required this.todos}) : super(key: key);
final List<Todo> todos;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Todos'),
),
body: ListView.builder(
itemCount: todos.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(todos[index].title),
// When a user taps the ListTile, navigate to the DetailScreen.
// Notice that you're not only creating a DetailScreen, you're
// also passing the current todo through to it.
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => DetailScreen(todo: todos[index]),
),
);
},
);
},
),
);
}
}
class DetailScreen extends StatelessWidget {
// In the constructor, require a Todo.
const DetailScreen({Key? key, required this.todo}) : super(key: key);
// Declare a field that holds the Todo.
final Todo todo;
#override
Widget build(BuildContext context) {
// Use the Todo to create the UI.
return Scaffold(
appBar: AppBar(
title: Text(todo.title),
),
body: Padding(
padding: const EdgeInsets.all(16.0),
child: Text(todo.description),
),
);
}
}
I can't get the FemaleBox and Operation in your project so I can't run that try the above example or share you full code include second screen also

Answer 3

add a constructor in your second screen and pass it while calling second screen
const SecondScreen(
{Key? key,required this.answer, })
: super(key: key);
final String? answer; //define value you want to pass
#override
_SecondScreenScreenState createState() => _SecondScreenState();
}
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SecondScreen(answer: 'Hello',),
));

Answer 4

There is another way to do that.
Create a class as given below and use static keyword to define any variable.
Now you can call this variable at your entire app via- Common.sharedData
So you can modified it according to you
Class Common{
static int sharedData=0;
//Other function
}

Answer 5

There are different ways to solve this
Sending parameters through constructor (Good solution).
Use a State Management package and hold the state in its class and access tit everywhere (Recommended way).
declare variable globally and use it anywhere in the app (not Recommended)