How to add TabBarView inside a widget element in BottomNavigationBar

Question

Now my app looks like below

I want to add a TabBar inside Browse widget. For now inside the browse widget it displays a simple text widget.

Code is as follows

import 'package:flutter/material.dart';

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

/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
  static const String _title = 'Flutter Code Sample';

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

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static const List<Widget> _widgetOptions = <Widget>[
   Text(
     'slkdfjds',
     style: optionStyle
   ),
    Text(
      'Shopping List Window',
      style: optionStyle,
    ),
    Text(
      'Account Window',
      style: optionStyle,
    ),
  ];

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Browse Flyers'),
      ),
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.label),
            title: Text('Browse'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.shopping_cart),
            title: Text('Shopping List'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.account_box),
            title: Text('Account'),
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.blue[300],
        onTap: _onItemTapped,
      ),
    );
  }
}

What I'm trying to achieve is to have a TabBarView like below when user clicks Browse tab

Answer 1

You can copy paste run full code below
You can define a Widget _tabSection() and put it in _widgetOptions
code snippet

@override
  initState() {
    _widgetOptions = <Widget>[
      _tabSection(),
      Text(
        'Shopping List Window',
        style: optionStyle,
      ),
      Text(
        'Account Window',
        style: optionStyle,
      ),
    ];
  }

  Widget _tabSection() {
    return DefaultTabController(
      length: 3,
      child: Column(
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
          Container(
            height: 50,

working demo

full code

import 'package:flutter/material.dart';

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

/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
  static const String _title = 'Flutter Code Sample';

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

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static List<Widget> _widgetOptions;

  @override
  initState() {
    _widgetOptions = <Widget>[
      _tabSection(),
      Text(
        'Shopping List Window',
        style: optionStyle,
      ),
      Text(
        'Account Window',
        style: optionStyle,
      ),
    ];
  }

  Widget _tabSection() {
    return DefaultTabController(
      length: 3,
      child: Column(
        mainAxisSize: MainAxisSize.max,
        children: <Widget>[
          Container(
            height: 50,
            color: Colors.black12,
            child: TabBar(
                labelColor: Colors.deepOrange,
                unselectedLabelColor: Colors.white,
                tabs: [
                  Tab(text: "SMALL"),
                  Tab(text: "MEDIUM"),
                  Tab(text: "LARGE"),
                ]),
          ),
          Expanded(
            child: Container(
              color: Colors.green,
              child: TabBarView(children: [
                Container(
                  child: Text("SMALL Body"),
                ),
                Container(
                  child: Text("MEDIUM Body"),
                ),
                Container(
                  child: Text("LARGE Body"),
                ),
              ]),
            ),
          ),
        ],
      ),
    );
  }

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Browse Flyers'),
      ),
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.label),
            title: Text('Browse'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.shopping_cart),
            title: Text('Shopping List'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.account_box),
            title: Text('Account'),
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.blue[300],
        onTap: _onItemTapped,
      ),
    );
  }
}

Answer 2

you need to create a widget Browse and then add your tabview to it. and then replace Text( 'slkdfjds', style: optionStyle ), with your new widget in my case TabBarDemo

an example

 import 'package:flutter/material.dart';

void main() {
  runApp(TabBarDemo());
}

class TabBarDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: 3,
        child: Scaffold(
          appBar: AppBar(
            bottom: TabBar(
              tabs: [
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
                Tab(icon: Icon(Icons.directions_bike)),
              ],
            ),
            title: Text('Tabs Demo'),
          ),
          body: TabBarView(
            children: [
              Icon(Icons.directions_car),
              Icon(Icons.directions_transit),
              Icon(Icons.directions_bike),
            ],
          ),
        ),
      ),
    );
  }
}

Answer 3

One of your desired bottom navigation bar views needs to have tab bar, like this:

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static List<Widget> _widgetOptions = <Widget>[
   DefaultTabController(
        length: 3,
        child: Scaffold(
          appBar: AppBar(
            bottom: TabBar(
              tabs: [
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
                Tab(icon: Icon(Icons.directions_bike)),
              ],
            ),
            title: Text('Tabs Demo'),
          ),
          body: TabBarView(
            children: [
              Icon(Icons.directions_car),
              Icon(Icons.directions_transit),
              Icon(Icons.directions_bike),
            ],
          ),
        ),
      ),
    Text(
      'Shopping List Window',
      style: optionStyle,
    ),
    Text(
      'Account Window',
      style: optionStyle,
    ),
  ];

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Browse Flyers'),
      ),
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.label),
            title: Text('Browse'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.shopping_cart),
            title: Text('Shopping List'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.account_box),
            title: Text('Account'),
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.blue[300],
        onTap: _onItemTapped,
      ),
    );
  }
}

This way only browse page has tab bar.