Tab

import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with TickerProviderStateMixin {
  TabController tabController;

  @override
  void initState() {
    tabController = TabController(vsync: this, length: 3);
    super.initState();
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('MyApp'),
      ),
      body: Container(
        child: Column(
          children: <Widget>[
            TabBar(
              controller: tabController,
              tabs: <Widget>[
                Tab(
                  icon: Icon(Icons.home,
                      color:
                          tabController.index == 0 ? Colors.red : Colors.green),
                ),
                Tab(
                  icon: Icon(Icons.ac_unit,
                      color:
                          tabController.index == 1 ? Colors.red : Colors.green),
                ),
                Tab(
                  icon: Icon(Icons.headset,
                      color:
                          tabController.index == 2 ? Colors.red : Colors.green),
                ),
              ],
            ),
            Expanded(
              child: TabBarView(
                controller: tabController,
                children: <Widget>[
                  Icon(Icons.home, size: 100.0),
                  Icon(Icons.ac_unit, size: 100.0),
                  Icon(Icons.headset, size: 100.0),
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}