import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primaryColor: Color(0xFF0f1e3d),
        // brightness: Brightness.dark
      ),
      debugShowCheckedModeBanner: false,
      home: MyTabbedPage(),
    );
  }
}

class MyTabbedPage extends StatefulWidget {
  const MyTabbedPage({Key key}) : super(key: key);
  @override
  _MyTabbedPageState createState() => new _MyTabbedPageState();
}

class _MyTabbedPageState extends State<MyTabbedPage>
    with SingleTickerProviderStateMixin {
  TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = new TabController(vsync: this, length: 2);
    _tabController.addListener(_handleTabChange);
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  void _handleTabChange() {
    setState(() {
      print("touched");
      index = _tabController.index;
      print(index);
    });
  }

  int index;

  @override
  Widget build(BuildContext context) {
    print(_tabController.index);
    return new Scaffold(
      appBar: new AppBar(
        bottom: new TabBar(
          controller: _tabController,
          onTap: (int i) {
            setState(() {
              print("touched");
              index = i;
              print(index);
            });
          },
          tabs: <Tab>[
            new Tab(
              text: index == 0 ? 'LEFT' : null,
              icon: index == 0 ? null : Icon(Icons.mail),
            ),
            new Tab(
              text: index == 1 ? 'RIGHT' : null,
              icon: index == 1 ? null : Icon(Icons.adb),
            ),
          ],
        ),
      ),
      body: new TabBarView(controller: _tabController, children: [
        Text("left"),
        Text("right"),
      ]),
    );
  }
}