使用flutter中的提供程序包在第三屏幕中进行任何更改时，如何在第一屏幕中更改文本？

如何解决使用flutter中的提供程序包在第三屏幕中进行任何更改时，如何在第一屏幕中更改文本？

我有一个名为有状态窗口小部件PlantFeatureScreen1的第一个屏幕，在其中发生更新时，我必须在第三个屏幕中显示更改，该屏幕也有一个有状态窗口小部件CartDetais3。

当在第三屏幕中发生更改并且在第三屏幕中添加了addQuantity和subtractQuantity功能时，如何更新第一屏幕？请建议使用提供程序包。

firstScreen代码在这里，我必须显示此小部件树的最后一个中心小部件中的更改。

class PlantFeatureScreen1 extends StatefulWidget {
  @override
  _PlantFeatureScreen1State createState() => _PlantFeatureScreen1State();
}

class _PlantFeatureScreen1State extends State<PlantFeatureScreen1> {


  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        TopAppBar(),Expanded(
          flex: 1,child: Align(
            alignment: Alignment(-1,0),child: Container(
              decoration: BoxDecoration(
                color: Colors.white,),child: Text(
                "Plants",style: TextStyle(fontSize: 30,fontWeight: FontWeight.w700),Expanded(
          flex: 5,child: Container(
            width: double.infinity,decoration: BoxDecoration(
              color: Colors.blue,child: DefaultTabController(
              length: 5,child: Column(
                children: [
                  Container(
                    height: 50,width: double.infinity,child: TabBar(
                      isScrollable: true,tabs: ourAllLists.tabMaker(),Container(
                    height: 317,decoration: BoxDecoration(color: Colors.white),child: TabBarView(
                      children: ourAllLists.tabViewerMaker(context),],Padding(
          padding: const EdgeInsets.fromLTRB(20,20,20),child: Container(
            alignment: Alignment.bottomRight,height: 120,child: Stack(
              overflow: Overflow.visible,children: [
                Container(
                  height: 70,width: 105,decoration: BoxDecoration(
                      color: Color(0xFF96CA2D),borderRadius: BorderRadiusDirectional.horizontal(
                          end: Radius.circular(32),start: Radius.circular(32))),child: Icon(FontAwesomeIcons.shoppingBag,color:Colors.white,size:30),Positioned(
                  // top: 0,bottom: 50,right: 0,child: Container(
                    height: 35,width: 35,decoration: BoxDecoration(
                      color: Colors.white,borderRadius: BorderRadius.circular(50),border: Border.all(color: Color(0xFF96CA2D),width: 4)
                    ),child: Center(child: Text(ourAllLists.totalquantity().toString(),style:TextStyle(fontSize: 20,color: Color(0xFF96CA2D)))),)
              ],)
      ],);
  }
}

thirdScreen代码在此处，更新是在单击+或-图标时发生的。

class CartDetais3 extends StatefulWidget {
  @override
  _CartDetais3State createState() => _CartDetais3State();
}

class _CartDetais3State extends State<CartDetais3> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: SafeArea(
            child: Scaffold(
      body: Padding(
        padding: const EdgeInsets.fromLTRB(8,8,15),child: Column(
          children: [
            TopAppBar(),Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,children: [
                Text(
                  "Cart",style: kPlantNameStyle,Text(
                  "\$" + "284",style: kItemPrice,Expanded(
              child: ListView.builder(
                  itemCount: OurAllLists.cartPlantList3.length,itemBuilder: (context,index) {
                    return Card(
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,children: [
                          Container(
                            height: 110,width: 100,child: Image(image: AssetImage("assets/tulip.png")),Container(
                            height: 80,width: 120,child: Column(
                              children: [
                                Text(OurAllLists.cartPlantList3[index].pN),Text(OurAllLists.cartPlantList3[index].ca
                                    .toUpperCase()),Text("\$ " +
                                    OurAllLists.cartPlantList3[index].pr
                                        .toString()),Container(
                              height: 120,child: Column(
                                children: [
                                  FlatButton(
                                    onPressed: () {
                                      setState(() {
                                        *here addQuantity function must go*
                                      });
                                    },child: Icon(
                                      FontAwesomeIcons.plus,size: 20,Text(OurAllLists.cartPlantList3[index].qu
                                      .toString()),FlatButton(
                                    onPressed: () {
                                      *here subtractQuantity function must go*
                                    },child: Icon(
                                      FontAwesomeIcons.minus,))
                        ],);
                  }),)
          ],)));
  }
}

我还有一个名为ViewTotallItemProvider

的单独的类

class ViewTotalItemProvider extends ChangeNotifier{
  addQuantity(index){
    OurAllLists.cartPlantList3[index].qu++;
    notifyListeners();
  }

  subtrachQuantity(index){
    OurAllLists.cartPlantList3[index].qu--;

  }
}