navigation.dart

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MainPage(),
    );
  }
}

class MainPage extends StatefulWidget {
  const MainPage({Key? key}) : super(key: key);

  @override
  State<MainPage> createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  int currentIndex = 0;
  final screens = const[
    HomePage(),
    BuisnessPage(),
    HomePage(),
    BuisnessPage(),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Bottom Navigation Bar'),
        centerTitle: true,
      ),
      body: screens[currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.white70,
        selectedItemColor: Colors.white,
        unselectedItemColor: Colors.grey,
        type: BottomNavigationBarType.fixed,
        iconSize: 30,
        //selectedFontSize: 16,
        //unselectedFontSize: 14,
        //showUnselectedLabels: false,
        currentIndex: currentIndex,
        onTap: (index) => setState(() => currentIndex = index),
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
            backgroundColor: Colors.red,
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.business),
            label: 'Business',
            backgroundColor: Colors.green,
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.school),
            label: 'School',
            backgroundColor: Colors.purple,
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.settings),
            label: 'Settings',
            backgroundColor: Colors.pink,
          ),
        ],
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          title: const Text('Test A'),
        ),
        body:
            const Center(child: Text('Test A', style: TextStyle(fontSize: 60))),
      );
}

class BuisnessPage extends StatelessWidget {
  const BuisnessPage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          title: const Text('Test B'),
        ),
        body:
            const Center(child: Text('Test B', style: TextStyle(fontSize: 60))),
      );
}