Tab bar view error as used the same GlobalKey multiple times - dart

Question

I'm using Flutter. I have a simple app with 3 tabs. There is a RefreshIndicator in each tab with a ListView. The rows are built in another method. This is the code:
#override
Widget build(BuildContext context) {
final GlobalKey<RefreshIndicatorState> _RIKey1 = new GlobalKey<RefreshIndicatorState>();
final GlobalKey<RefreshIndicatorState> _RIKey2 = new GlobalKey<RefreshIndicatorState>();
final GlobalKey<RefreshIndicatorState> _RIKey3 = new GlobalKey<RefreshIndicatorState>();
debugPrint(_RIKey1.toString());
debugPrint(_RIKey2.toString());
debugPrint(_RIKey3.toString());
return new Scaffold(
body: new DefaultTabController(
length: 3,
child: new Scaffold(
appBar: new AppBar(
actions: <Widget>[
IconButton(
icon: Icon(Icons.refresh),
onPressed: () {
_RIKey1.currentState.show();
},
)
],
bottom: new TabBar(
tabs: [
new Tab(icon: new Icon(Icons.view_list)),
new Tab(icon: new Icon(Icons.hotel)),
new Tab(icon: new Icon(Icons.assessment)),
],
),
title: new Text('Data'),
),
body: new TabBarView(
children: [
new RefreshIndicator(
key: _RIKey1,
onRefresh: _actualizoData1,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 5.0),
itemCount: linea_reservas.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRow(index);
}),
),
new RefreshIndicator(
key: _RIKey2,
onRefresh: _actualizoData2,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 8.0),
itemCount: linea_inouthouse.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRowInOutHouse(index);
}),
),
new RefreshIndicator(
key: _RIKey3,
onRefresh: _actualizoData3,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 5.0),
itemCount: linea_ocupacion.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRowOcupacion(index);
}),
),
],
),
),
),
);
}
the app works, but after changing tabs a few times, it crashes with this error:
I/flutter ( 5252): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 5252): The following assertion was thrown building NotificationListener<KeepAliveNotification>:
I/flutter ( 5252): Multiple widgets used the same GlobalKey.
I/flutter ( 5252): The key [LabeledGlobalKey<RefreshIndicatorState>#7bd42] was used by multiple widgets. The parents of
I/flutter ( 5252): those widgets were:
I/flutter ( 5252): - RepaintBoundary-[<[LabeledGlobalKey<RefreshIndicatorState>#7bd42]>](renderObject:
I/flutter ( 5252): RenderRepaintBoundary#60a4a DETACHED)
I/flutter ( 5252): - RepaintBoundary-[<[LabeledGlobalKey<RefreshIndicatorState>#7bd42]>](renderObject:
I/flutter ( 5252): RenderRepaintBoundary#c8cdb NEEDS-LAYOUT NEEDS-PAINT)
I/flutter ( 5252): A GlobalKey can only be specified on one widget at a time in the widget tree.
I searched online an found an StackOverflow solution Multiple widgets used the same GlobalKey to use custom keys:
import 'package:flutter/widgets.dart';
class RIKeys {
static final riKey1 = const Key('__RIKEY1__');
static final riKey2 = const Key('__RIKEY2__');
static final riKey3 = const Key('__RIKEY3__');
}
Now it works as intended but I'm not sure how I can declare it on state class and show the currentState.show() when the user taps on refresh button on the app bar as below:
GlobalKey<RefreshIndicatorState> _RIKey1 = new GlobalKey<RefreshIndicatorState>();
_RIKey1.currentState.show();
I'm not sure how to overcome this issue please advise. Thank you for any help.