How to get the current tab index in Flutter?

• General

The flutter tabcontroller index does not respond to changes in the tabbarview. Flutter tabcontroller detects the change in the tabbar but does not know the change in the tabbarview. Listener causes the text of the floatingactionbutton to change, but there is no response when the tabbarview changes. Let’s get started with How to get the current tab index in Flutter!

Also, check the TabBar Widget

How to get the current tab index in Flutter??

You can get current index by DefaultTabController.of(context).index; as follows:

...
appBar: AppBar(
  bottom: TabBar(
    tabs: [
      Tab(~), Tab(~)
    ]
  ),
  actions: [
    // At here you have to get `context` from Builder.
    // If you are not sure about this, check InheritedWidget document.
    Builder(builder: (context){
      final index = DefaultTabController.of(context).index;   
      // use index at here... 
    })
  ]
)

You can also add a listener to listen to changes in tabs like the below given example:

tabController = TabController(vsync: this, length: 4)
   ..addListener(() {
setState(() {
  switch(tabController.index) {
    case 0:
      // some code here
    case 1:
     // some code here
  }
  });
});

By using DefaultTabController, you can get the current index easily whether the user changes tabs by Swiping or Tapping on the tab bar.

You must wrap your Scaffold inside of a Builder and you can then retrieve the tab index with DefaultTabController.of(context).index inside Scaffold.

This is a nice example:

DefaultTabController(
    length: 3,
    child: Builder(builder: (BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text('Home'),
          bottom: TabBar(
              isScrollable: true,
              tabs: [Text('0'), Text('1'), Text('2')]),
        ),
        body: _buildBody(),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            print(
                'Current Index: ${DefaultTabController.of(context).index}');
          },
        ),
      );
    }),
  ),

The reason for using DefaultTabController is for it to manage tabs by itself.

If you want some custom tab management, use TabController instead. By using TabController you can have much more information(including the Current index).

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

class _MyTabbedPageState extends State<MyTabbedPage>
    with SingleTickerProviderStateMixin {
  final List<Tab> myTabs = <Tab>[
    new Tab(text: 'LEFT'),
    new Tab(text: 'RIGHT'),
  ];

  TabController _tabController;

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

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

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        bottom: new TabBar(
          controller: _tabController,
          tabs: myTabs,
        ),
      ),
      body: new TabBarView(
        controller: _tabController,
        children: myTabs.map((Tab tab) {
          return new Center(child: new Text(tab.text));
        }).toList(),
      ),
    );
  }
}

Conclusion:

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So, In today’s article, we have learned How to get the current tab index in Flutter!

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also, go read the article for Customizing TabBar Width In Flutter.

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Written by Nirali Patel

Nirali Patel is a dedicated Flutter developer with over two years of experience, specializing in creating seamless mobile applications using Dart. With a passion for crafting user-centric solutions, Nirali combines technical proficiency with innovative thinking to push the boundaries of mobile app development.