ThemeData extension method throw exception when the ThemeExtension is null #103313
Description
Steps to Reproduce
- Run code below
- Change themeMode to dark
Expected results: No Exception
Actual results: Exception
Code sample
import 'package:flutter/material.dart';
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
runApp(const App());
}
class App extends StatelessWidget {
const App({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
themeMode: ThemeMode.light,
theme: ThemeData(
brightness: Brightness.light,
extensions: {
const MyTheme(
heading47: TextStyle(
color: Colors.red,
),
),
},
),
darkTheme: ThemeData(
brightness: Brightness.dark,
),
home: const Home(),
);
}
}
class Home extends StatelessWidget {
const Home({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Title'),
),
body: Center(
child: Text(
'Heading47',
style: MyTheme.maybeOf(context)?.heading47,
),
),
);
}
}
@immutable
class MyTheme extends ThemeExtension<MyTheme> {
const MyTheme({
required this.heading47,
});
final TextStyle heading47;
@override
ThemeExtension<MyTheme> copyWith({
TextStyle? heading47,
}) {
return MyTheme(heading47: heading47 ?? this.heading47);
}
@override
ThemeExtension<MyTheme> lerp(
ThemeExtension<MyTheme>? other,
double t,
) {
if (other is! MyTheme) return this;
return MyTheme(
heading47: TextStyle.lerp(heading47, other.heading47, t)!,
);
}
@override
bool operator ==(Object other) {
if (other is! MyTheme) return false;
return other.heading47 == heading47;
}
@override
int get hashCode => Object.hashAll([heading47]);
static MyTheme? maybeOf(BuildContext context) {
return Theme.of(context).extension<MyTheme>();
}
static MyTheme of(BuildContext context) {
return Theme.of(context).extension<MyTheme>()!;
}
}Logs
_CastError (type 'Null' is not a subtype of type 'MyTheme' in type cast)
[√] Flutter (Channel beta, 2.13.0-0.4.pre, on Microsoft Windows [Version
10.0.22000.613], locale en-ID)
• Flutter version 2.13.0-0.4.pre at C:\flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 25caf1461b (3 days ago), 2022-05-05 14:23:09
-0700
• Engine revision c5caf749fe
• Dart version 2.17.0 (build 2.17.0-266.8.beta)
• DevTools version 2.12.2
[√] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
• Android SDK at C:\Users\andre\AppData\Local\Android\sdk
• Platform android-31, build-tools 31.0.0
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)
• All Android licenses accepted.
[√] Chrome - develop for the web
• Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe
[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.11.9)
• Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community
• Visual Studio Community 2019 version 16.11.32106.194
• Windows 10 SDK version 10.0.19041.0
[√] Android Studio (version 2021.1)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin can be installed from:
https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)
[√] VS Code (version 1.67.0)
• VS Code at C:\Users\andre\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 3.40.0
[√] Connected device (3 available)
• Windows (desktop) • windows • windows-x64 • Microsoft Windows [Version 10.0.22000.613]
• Chrome (web) • chrome • web-javascript • Google Chrome 100.0.4896.127
• Edge (web) • edge • web-javascript • Microsoft Edge 101.0.1210.39
[√] HTTP Host Availability
• All required HTTP hosts are available
This cast should be changed to
as T? instead