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: [
              Page1(),
              Page2(),
              Page3(),
            ],
          ),
        ),
      ),
    );
  }
}

class Page1 extends StatefulWidget{
  
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState

    return _Page1State();
  }

class _Page1State extends State<Page1> with AutomaticKeepAliveClientMixin{ 
  @override
    void initState() {
      super.initState();
      print("Page 1 init");
    }
  @override
  Widget build(BuildContext context) {
    super.build(context);
    return Text("Page 1");
  }
  @override
  bool get wantKeepAlive => true;

}