Flutter issues share

main.dart

import 'dart:async';

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, this.title}) : super(key: key);

  final String? title;

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

class _MyHomePageState extends State<MyHomePage> {
  List<Widget> _widgets = [MyStatefulWidget()];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ListView.separated(
          itemCount: _widgets.length,
          itemBuilder: (_, index) {
            return _widgets[index];
          },
          separatorBuilder: (BuildContext context, int index) {
            return SizedBox(
              width: 5,
            );
          },
        ),
      ),
      floatingActionButton: TextButton(
        onPressed: () {
          setState(() {
            // Insert first in the list, hope it's just need to rebuild only the first item, the remains are unchanged
            _widgets.insert(0, MyStatefulWidget());
          });
        },
        child: Container(
          child: Text(
            'Press',
            style: TextStyle(
              color: Colors.white,
              fontSize: 24,
            ),
          ),
          padding: EdgeInsets.all(10),
          decoration: BoxDecoration(
            color: Colors.red,
          ),
        ),
      ),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<StatefulWidget> createState() {
    print('>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> createState');
    return _MyStatefulState();
  }
}

class _MyStatefulState extends State<MyStatefulWidget> {
  StreamSubscription? countdownSubscription;
  int countdownTime = 30;

  @override
  void initState() {
    super.initState();
    initTimeoutUI();
  }

  void initTimeoutUI() {
    countdownSubscription = Future.delayed(Duration(seconds: 1)).asStream().listen((value) {
      if (countdownTime > 0) {
        setState(() {
          countdownTime--;
        });
      }
      initTimeoutUI();
    });
  }

  @override
  void dispose() {
    super.dispose();
    countdownSubscription?.cancel();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      width: 100,
      height: 100,
      child: Center(child: Text('countdown: $countdownTime')),
    );
  }
}