Create an array list in the flutter

Question

I have two pages. On the first page I want to return a list. I want to insert in this list the values that come from the second page. So the flow is more or less the following: I enter the second page, send the value to the first page, save to an array type variable and display all values in a list.

The problem is that I can’t create the list. I can only display the last data I send instead of the list of everything I’ve sent.

Here’s the code:

Front page

import 'package:flutter/material.dart';

class PageTwo extends StatefulWidget {
  final String descricao;
  const PageTwo({Key key, this.descricao}) : super(key: key);

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

class _PageTwoState extends State<PageTwo> {
  final List<String> listDescricao = [];

  @override
  void initState() {
    listDescricao.add(widget.descricao);
    super.initState();
  }

  //List images items
  Widget imgListItem() {
    return ListView.builder(
        itemCount: listDescricao.length,
        itemBuilder: (BuildContext context, int index) {
          return widget.descricao == null
              ? Container()
              : Text(listDescricao[index]);
        });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: imgListItem(),
    );
  }
}

Second page

import 'package:flutter/material.dart';

class PageOne extends StatefulWidget {
  @override
  _PageOneState createState() => _PageOneState();
}

class _PageOneState extends State<PageOne> {
  final GlobalKey<ScaffoldState> _scaffoldkey = new GlobalKey<ScaffoldState>();
  final inputDescricaoController = TextEditingController();

  //send image
  doSend() async {
    String descricao = inputDescricaoController.text ??= "";

    Navigator.of(context).pushAndRemoveUntil(
        MaterialPageRoute(
            builder: (BuildContext context) => PageTwo(descricao: descricao)),
        (Route<dynamic> route) => false);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: <Widget>[
          TextField(
                controller: inputDescricaoController,
            ),
          RaisedButton(
        child: Column(
          children: <Widget>[

            Text(
              'send',
            ),
          ],
        ),
        onPressed: () async {
          doSend();
        },
      ),
        ]
      ) 

    );
  }
}

Answer 1

I created an example of how you can do what you want, you can run it by Dartpad to test

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: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

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

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

class _MyWidgetState extends State<MyWidget> {

  List<String> dataList = [];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: ListView.builder(
          itemCount: dataList.length,
          itemBuilder: (_, int index){
            return Text(dataList[index]);
          },
        )
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: (){
          Navigator.push(
            context,
            MaterialPageRoute(builder: (context) => ScreenTwo()),
          ).then((result){
            setState((){
              dataList.add(result);
            });
          });
        }
      ),
    );
  }
}

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

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

class _ScreenTwoState extends State<ScreenTwo> {

  TextEditingController controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: Column(
          children: <Widget>[
            TextField(
              controller: controller
            ),
            RaisedButton(
              child: Text("Salvar"),
              onPressed: (){
                Navigator.of(context).pop(controller.text);
              },
            )
          ],
        )
      ),
    );
  }
}