How can i make some screens with bottom menu - menu

Question

I'm making a bottom menu. I want make 3 screens. and for this i want make 3 single classes. 1 the screen - 1 a class. And for this all using 1 the Scaffold. How can i do it? All my classes must be a StateFull for using function "setState"
I was found in google source codes. but they for single widget
import 'package:flutter/material.dart';
import 'package:async/async.dart';
class MyHomePage extends StatefulWidget {
MyHomePage({Key key}) : super(key: key);
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _selectedIndex = 1;
final _widgetOptions = [
Text('Index 0: Home'),
Text('Index 1: Business'),
Text('Index 2: School'),
];
#override
Widget build(BuildContext context) {
//API_Tumbler api = new API_Tumbler("3EuKq8hIimaGFxY3wqzL7MXw5qZuN3Zcx9cIEgWKT4UTINwGec", "gjkCRximp0OJtFGN4Zd8xD2yPMwjw557EtgVvKhmqLNdI9IOBx");
return Scaffold(
appBar: AppBar(
title: Text("Miner of Memes"),
),
body: Center(
child: _widgetOptions.elementAt(_selectedIndex),
),
bottomNavigationBar: BottomNavigationBar(
items: [
new BottomNavigationBarItem(
icon: Icon(Icons.library_books),
title: Text('Блоги'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.subject),
title: Text('Лента'),
),
new BottomNavigationBarItem(
icon: Icon(Icons.send),
title: Text('Отправка')
)
],
currentIndex: _selectedIndex,
onTap: _onItemTapped,
),
);
}
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
}

Answer 1

This is can be done by replacing the Text widget with the classname in
_widgetOptions.
Make a file lets say firstScreen.dart with the following code :
class Firstscreen extends StatefulWidget {
const FirstScreen({ Key key }) : super(key: key);
#override
_FirstScreenState createState() => _FirstScreenState();
}
class _FirstScreenState extends State<FirstScreen> {
#override
Widget build(BuildContext context) {
return Text("This is FirstScreen);
}
}
now in your code edit this.
import './firstScreen.dart' //include the file created
...
final _widgetOptions = [
FirstScreen(),
Text('Index 1: Business'),
Text('Index 2: School'),
];
Just do same for other screens too.
Hope it helps you :)