如何让底部导航栏通过onSelected进行页面切换？

import 'package:flutter/material.dart';

class BottomNavigationBarDemo extends StatefulWidget {
  @override
  _BottomNavigationBarDemoState createState() => _BottomNavigationBarDemoState();
}

class _BottomNavigationBarDemoState extends State<BottomNavigationBarDemo> {
  int currentIndex = 0;

  List<Widget> pages = [
    HomePage(),
    NewsPage(),
    ProfilePage(),
  ];

  void onTabSelected(int index) {
    setState(() {
      currentIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: pages[currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: currentIndex,
        onTap: onTabSelected,
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.newspaper),
            label: 'News',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.person),
            label: 'Profile',
          ),
        ],
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Home Page'),
    );
  }
}

class NewsPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('News Page'),
    );
  }
}

class ProfilePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Profile Page'),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: BottomNavigationBarDemo(),
  ));
}