How to navigate tab from another dart file button tap event?

Question

How to navigate tab from another dart file button tap event? I am using Tabmanager. It only works with the same dart file. I am having error in

TabManager._myTabbedPageKey.currentState._tabController
                .animateTo(1);

main.dart

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

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

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

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: 2,
        child: Scaffold(
          appBar: AppBar(
            bottom: TabBar(
              tabs: [
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
              ],
            ),
            title: Text('Tabs Demo'),
          ),
          body: TabBarView(
            children: [
              new TabA(),
              new TabB(),
            ],
          ),
        ),
      ),
    );
  }
}

class TabManager extends StatefulWidget {
  static final _myTabbedPageKey = new GlobalKey<_MyAppState>();
  @override
  _TabManagerState createState() => _TabManagerState();
}
class _TabManagerState extends State<TabManager> {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: new MyApp(
        key: TabManager._myTabbedPageKey,
      ),
    );
  }
}

Here tabA.dart is a separate dart file. An error shows like

The getter '_myTabbedPageKey' isn't defined for the type 'TabManager'.

tabA.dart

    class TabA extends StatefulWidget {
  @override
  _TabAState createState() => _TabAState();
}

class _TabAState extends State<TabA> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: GestureDetector(
          onTap: () {
            TabManager._myTabbedPageKey.currentState._tabController
                .animateTo(1);
          },
          child: Text('taba')),
    );
  }
}

Answer 1

Try to This Code very similar

working demo

import 'package:flutter/material.dart';

void main() {

runApp(MyApp()); }

class MyApp extends StatelessWidget {

@override

Widget build(BuildContext context) {

return MaterialApp(

  home: DefaultTabController(

    length: 3,

    child: Scaffold(

      appBar: AppBar(

        bottom: TabBar(
          tabs: [

            Tab(text: 'Home'),

            Tab(text: 'Messages',),

            Tab(text: 'Call'),

          ],
        ),
        title: Text('MY App'),

      ),

      body: TabBarView(

        children: [
         new  Home(),

         new  Messages(),

          new Call()
        ],
      ),
    ),
  ),
);

} }

class Home extends StatelessWidget {

@override Widget build(BuildContext context) {

return MaterialApp(

    debugShowCheckedModeBanner: false,

    home: Scaffold(

        body: Center(

            child:
            Text('Home',
              style: TextStyle(fontSize: 21),)
        )
    )
);

} }

class Messages extends StatelessWidget {

@override

Widget build(BuildContext context) {

return MaterialApp(

    debugShowCheckedModeBanner: false,

    home: Scaffold(

        body: Center(

            child:
            Text('Meassage',
              style: TextStyle(fontSize: 21),)
        )
    )
);

} }

class Call extends StatelessWidget {

@override

Widget build(BuildContext context) {

return MaterialApp(

    debugShowCheckedModeBanner: false,

    home: Scaffold(

        body: Center(

            child:
            Text('Call',
              style: TextStyle(fontSize: 21),)
        )
    )
);

} }