main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
          brightness: Brightness.dark,
          primaryColor: Colors.blueGrey,
          useMaterial3: true),
      home: Scaffold(body: W()),
      debugShowCheckedModeBanner: false,
    );
  }
}

class W extends StatefulWidget {
  const W({
    super.key,
  });

  @override
  State<W> createState() => _WState();
}

class _WState extends State<W> {
  List<Widget> l = [];

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

    Stream<int> f() async* {
      for (int i = 0; i < 100; ++i) {
        await Future.delayed(Duration(seconds: 1));
        yield i;
      }
    }

    f().listen((d) {
      setState(
          () => this.l.add(Card(child: ListTile(title: Text(d.toString())))));
    });
  }

  @override
  Widget build(BuildContext context) {
    print('build(): ${this.l.length}');
    return ListView(children: this.l);
  }
}