challenge01_final.dart

import 'dart:async';
import 'package:flutter/material.dart';

class AnimatedListExample extends StatefulWidget {
  @override
  _AnimatedListExampleState createState() => _AnimatedListExampleState();
}

class _AnimatedListExampleState extends State<AnimatedListExample> {
  final List<String> _items = [];
  final StreamController<List<String>> _streamController = StreamController<List<String>>();
  final GlobalKey<AnimatedListState> _listKey = GlobalKey<AnimatedListState>();

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

    Stream.periodic(Duration(seconds: 2), (count) => 'Item ${count + 1}')
        .take(10)
        .listen((item) {
      _items.add(item);
      _streamController.add(_items);
      _listKey.currentState?.insertItem(_items.length - 1);
    });
  }

  @override
  void dispose() {
    _streamController.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated List Example'),
      ),
      body: StreamBuilder<List<String>>(
        stream: _streamController.stream,
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return Center(child: CircularProgressIndicator());
          }

          return AnimatedList(
            key: _listKey,
            initialItemCount: snapshot.data!.length,
            itemBuilder: (context, index, animation) {
              return FadeTransition(
                opacity: animation,
                child: ListTile(
                  title: Text(snapshot.data![index]),
                ),
              );
            },
          );
        },
      ),
    );
  }
}

void main() => runApp(MaterialApp(home: AnimatedListExample()));