// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // Flutter code sample for StreamBuilder import 'dart:async'; import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); class MyApp extends StatelessWidget { const MyApp({super.key}); static const String _title = 'Flutter Code Sample'; @override Widget build(BuildContext context) { return const MaterialApp( title: _title, home: MyStatefulWidget(), ); } } class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({super.key}); @override State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); } class _MyStatefulWidgetState extends State<MyStatefulWidget> { final Stream<int> _bids = (() { late final StreamController<int> controller; controller = StreamController<int>( onListen: () async { await Future<void>.delayed(const Duration(seconds: 1)); controller.add(1); await Future<void>.delayed(const Duration(seconds: 1)); await controller.close(); }, ); return controller.stream; })(); @override Widget build(BuildContext context) { return DefaultTextStyle( style: Theme.of(context).textTheme.headline2!, textAlign: TextAlign.center, child: Container( alignment: FractionalOffset.center, color: Colors.white, child: StreamBuilder<int>( stream: _bids, builder: (BuildContext context, AsyncSnapshot<int> snapshot) { List<Widget> children; if (snapshot.hasError) { children = <Widget>[ 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: ${snapshot.stackTrace}'), ), ]; } else { switch (snapshot.connectionState) { case ConnectionState.none: children = const <Widget>[ Icon( Icons.info, color: Colors.blue, size: 60, ), Padding( padding: EdgeInsets.only(top: 16), child: Text('Select a lot'), ), ]; break; case ConnectionState.waiting: children = const <Widget>[ SizedBox( width: 60, height: 60, child: CircularProgressIndicator(), ), Padding( padding: EdgeInsets.only(top: 16), child: Text('Awaiting bids...'), ), ]; break; case ConnectionState.active: children = <Widget>[ const Icon( Icons.check_circle_outline, color: Colors.green, size: 60, ), Padding( padding: const EdgeInsets.only(top: 16), child: Text('\$${snapshot.data}'), ), ]; break; case ConnectionState.done: children = <Widget>[ const Icon( Icons.info, color: Colors.blue, size: 60, ), Padding( padding: const EdgeInsets.only(top: 16), child: Text('\$${snapshot.data} (closed)'), ), ]; break; } } return Column( mainAxisAlignment: MainAxisAlignment.center, children: children, ); }, ), ), ); } }