flutter/examples/api/lib/material/navigation_bar/navigation_bar.0.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

/// Flutter code sample for [NavigationBar].

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

class NavigationBarApp extends StatelessWidget {
  const NavigationBarApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(theme: ThemeData(useMaterial3: true), home: const NavigationExample());
  }
}

class NavigationExample extends StatefulWidget {
  const NavigationExample({super.key});

  @override
  State<NavigationExample> createState() => _NavigationExampleState();
}

class _NavigationExampleState extends State<NavigationExample> {
  int currentPageIndex = 0;

  @override
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    return Scaffold(
      bottomNavigationBar: NavigationBar(
        onDestinationSelected: (int index) {
          setState(() {
            currentPageIndex = index;
          });
        },
        indicatorColor: Colors.amber,
        selectedIndex: currentPageIndex,
        destinations: const <Widget>[
          NavigationDestination(
            selectedIcon: Icon(Icons.home),
            icon: Icon(Icons.home_outlined),
            label: 'Home',
          ),
          NavigationDestination(
            icon: Badge(child: Icon(Icons.notifications_sharp)),
            label: 'Notifications',
          ),
          NavigationDestination(
            icon: Badge(label: Text('2'), child: Icon(Icons.messenger_sharp)),
            label: 'Messages',
          ),
        ],
      ),
      body:
          <Widget>[
            /// Home page
            Card(
              shadowColor: Colors.transparent,
              margin: const EdgeInsets.all(8.0),
              child: SizedBox.expand(
                child: Center(child: Text('Home page', style: theme.textTheme.titleLarge)),
              ),
            ),

            /// Notifications page
            const Padding(
              padding: EdgeInsets.all(8.0),
              child: Column(
                children: <Widget>[
                  Card(
                    child: ListTile(
                      leading: Icon(Icons.notifications_sharp),
                      title: Text('Notification 1'),
                      subtitle: Text('This is a notification'),
                    ),
                  ),
                  Card(
                    child: ListTile(
                      leading: Icon(Icons.notifications_sharp),
                      title: Text('Notification 2'),
                      subtitle: Text('This is a notification'),
                    ),
                  ),
                ],
              ),
            ),

            /// Messages page
            ListView.builder(
              reverse: true,
              itemCount: 2,
              itemBuilder: (BuildContext context, int index) {
                if (index == 0) {
                  return Align(
                    alignment: Alignment.centerRight,
                    child: Container(
                      margin: const EdgeInsets.all(8.0),
                      padding: const EdgeInsets.all(8.0),
                      decoration: BoxDecoration(
                        color: theme.colorScheme.primary,
                        borderRadius: BorderRadius.circular(8.0),
                      ),
                      child: Text(
                        'Hello',
                        style: theme.textTheme.bodyLarge!.copyWith(
                          color: theme.colorScheme.onPrimary,
                        ),
                      ),
                    ),
                  );
                }
                return Align(
                  alignment: Alignment.centerLeft,
                  child: Container(
                    margin: const EdgeInsets.all(8.0),
                    padding: const EdgeInsets.all(8.0),
                    decoration: BoxDecoration(
                      color: theme.colorScheme.primary,
                      borderRadius: BorderRadius.circular(8.0),
                    ),
                    child: Text(
                      'Hi!',
                      style: theme.textTheme.bodyLarge!.copyWith(
                        color: theme.colorScheme.onPrimary,
                      ),
                    ),
                  ),
                );
              },
            ),
          ][currentPageIndex],
    );
  }
}