1
0
mirror of https://github.com/flutter/samples.git synced 2025-11-09 06:18:49 +00:00
Files
samples/null_safety/null_unsafe_app/lib/main.dart
2022-03-08 10:58:41 +10:00

89 lines
2.6 KiB
Dart
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
// Copyright 2020, the Flutter project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:window_size/window_size.dart';
void main() {
setupWindow();
runApp(const MyApp());
}
const double windowWidth = 400;
const double windowHeight = 400;
void setupWindow() {
if (!kIsWeb && (Platform.isWindows || Platform.isLinux || Platform.isMacOS)) {
WidgetsFlutterBinding.ensureInitialized();
setWindowTitle('Weather');
setWindowMinSize(const Size(windowWidth, windowHeight));
}
}
// This app simulates possible null errors. Try running it and see if it fails.
// You can then try to hot reload a few times; you should see it occasionally
// failing and occasionally succeeding.
class MyApp extends StatelessWidget {
const MyApp({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
// Get data from services. Note: in a real application,
// these would be async calls, but were using sync calls
// for simplicity.
final localizedAppName = Config.getAppName();
final temperatures = WeatherService.getTemperatures();
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: Text(localizedAppName)),
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
const Text('Temperature next 3 days:'),
for (final t in temperatures) Text(t.round().toString()),
],
),
),
),
);
}
}
class Config {
static String getAppName() {
// Imagine this looks up a localized version of the app name. We're using
// the current time to simulate a variance in responses.
if (DateTime.now().second.isEven) {
return 'Weather forecast';
} else {
// Oops, we don't have a localization.
return null;
}
}
}
class WeatherService {
static List<double> getTemperatures() {
// Imagine this makes a network call to get the current temperature.
// We're using the current time to simulate a variance in responses.
if (DateTime.now().millisecond.isEven) {
return [32.2, 34.5, 31.0];
} else {
if ((DateTime.now().second / 10).round().isEven) {
// Oops, we couldn't get any temperatures.
return null;
} else {
// Oops, we couldn't get one of the temperatures.
return [32.2, 34.5, null, 31.0];
}
}
}
}