```dart import 'dart:async'; import 'package:flutter/material.dart'; /// Flutter code sample for [StreamBuilder]. void main() => runApp(const StreamBuilderExampleApp()); class StreamBuilderExampleApp extends StatelessWidget { const StreamBuilderExampleApp({super.key}); @override Widget build(BuildContext context) { return const MaterialApp( home: StreamBuilderExample(), ); } } class StreamBuilderExample extends StatefulWidget { const StreamBuilderExample({super.key}); @override State createState() => _StreamBuilderExampleState(); } class _StreamBuilderExampleState extends State { final Stream _bids = (() { late final StreamController controller; controller = StreamController( onListen: () async { await Future.delayed(const Duration(seconds: 1)); controller.add(1); await Future.delayed(const Duration(seconds: 1)); await controller.close(); }, ); return controller.stream; })(); @override Widget build(BuildContext context) { return DefaultTextStyle( style: Theme.of(context).textTheme.displayMedium!, textAlign: TextAlign.center, child: Container( alignment: FractionalOffset.center, color: Colors.white, child: StreamBuilder( stream: _bids, builder: (BuildContext context, AsyncSnapshot snapshot) { List children; if (snapshot.hasError) { children = [ const Icon( Icons.error_outline, color: Colors.red, size: 60, ), Padding( padding: const EdgeInsets.only(top: 16), child: Text('Error: ${snapshot.error}'), ), Padding( padding: const EdgeInsets.only(top: 8), child: Text('Stack trace: ${snapshot.stackTrace}'), ), ]; } else { switch (snapshot.connectionState) { case ConnectionState.none: children = const [ Icon( Icons.info, color: Colors.blue, size: 60, ), Padding( padding: EdgeInsets.only(top: 16), child: Text('Select a lot'), ), ]; case ConnectionState.waiting: children = const [ SizedBox( width: 60, height: 60, child: CircularProgressIndicator(), ), Padding( padding: EdgeInsets.only(top: 16), child: Text('Awaiting bids...'), ), ]; case ConnectionState.active: children = [ const Icon( Icons.check_circle_outline, color: Colors.green, size: 60, ), Padding( padding: const EdgeInsets.only(top: 16), child: Text('\$${snapshot.data}'), ), ]; case ConnectionState.done: children = [ const Icon( Icons.info, color: Colors.blue, size: 60, ), Padding( padding: const EdgeInsets.only(top: 16), child: Text('\$${snapshot.data} (closed)'), ), ]; } } return Column( mainAxisAlignment: MainAxisAlignment.center, children: children, ); }, ), ), ); } } ```