Update a Listview in a Statefulwidget Son Flutter

Question

my main layout features an aapBar, body and bottomNavigationBar through the bottomNavigationBar I update the body with other screens, which show a listview, in the appBar from the main screen I have a delete all button, I can not update the Listview from the open screen in body... The data from this Listview comes from a Futurebuilder, how can I do that? Darpat: Example on the Dartpad

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: MyWidget(),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  _menuSel(String itemText) {
    switch (itemText) {
      case "Marcar todos":
        print("ItemSel Marcar todos");
        break;
      case "Desmarcar todos":
        print("Excluindo registros do banco e atualizar liste view Tela1");
        //função exclui itens do bd atualizar Scaffold/ListView em Tela1 ou Tela2
        break;
    }
  }

  int _indiceNav = 0;

  List<String> itensMenu = ["Marcar todos", "Desmarcar todos"];

  List<Widget> telas = [
    Tela1(),
    Tela2(),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        automaticallyImplyLeading: false,
        title: Text("principal"),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.search),
            onPressed: () {},
          ),
          PopupMenuButton<String>(
            onSelected: _menuSel,
            itemBuilder: (context) {
              return itensMenu.map((String item) {
                return PopupMenuItem<String>(
                  value: item,
                  child: Text(item),
                );
              }).toList();
            },
          ),
        ],
      ),
      body: telas[_indiceNav],
      bottomNavigationBar: BottomNavigationBar(
          currentIndex: _indiceNav,
          onTap: (indice) {
            print("pressionado $indice");
            setState(() {
              _indiceNav = indice;
            });
          },
          items: [
            BottomNavigationBarItem(
                title: Text("Tela1"), icon: Icon(Icons.alarm)),
            BottomNavigationBarItem(
                title: Text("Tela2"), icon: Icon(Icons.list)),
          ]),
    );
  }
}

class Tela1 extends StatefulWidget {
  @override
  _Tela1State createState() => _Tela1State();
}

class _Tela1State extends State<Tela1> {
  @override
  Widget build(BuildContext context) {
    return Text("TEla 1");
    //return Scaffold(body: FutureBuilder... ListView...);
  }
}

class Tela2 extends StatefulWidget {
  @override
  _Tela2State createState() => _Tela2State();
}

class _Tela2State extends State<Tela2> {
  @override
  Widget build(BuildContext context) {
    return Text("TEla 2");
    //return Scaffold(body: FutureBuilder... ListView...);
  }
}

In the main project, Tela1, and Tela2 are separate files. In short, I need to access methods and update the open body screens!

Answer 1

I created an example for you that can be tested on Dartpad....

Since you haven’t shown us how your complete code is, try applying my example to your case, which you should solve:

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

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

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

class _MyAppState extends State<MyApp> {
  final List<String> list = ["Item 2", "Item 2", "Item 3", "Item 4", "Item 5"];

  Future<List<String>> getData(){
    return Future.value(list);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: FutureBuilder(
          future: getData(),
          builder: (_, data){
            return ListView.builder(
              itemCount: list.length,
              itemBuilder: (_, int index){
                return Text(list[index].toString());
              }
            );
          },
        ),
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.close), 
          onPressed: (){
            setState((){
              list.clear();
            });
          },
        )
      ),
    );
  }
}

Observing

This code, my example, is related to only one screen, so you will have to apply in both