[英]Error: Android studio Flutter BlocBuilder builder not detecting return statement from a switch case statement
The switch-case statement from a flutter blocbuilder is not recognising the return statement.来自 flutter blocbuilder 的 switch-case 语句无法识别 return 语句。 I dont understand why this is happening.我不明白为什么会这样。
The body might complete normally, causing 'null' to be returned, but the return type, 'Widget', is a potentially non-nullable type. (Documentation) Try adding either a return or a throw statement at the end.
This is the code这是代码
WelcomeScreenNavigationState>(
builder: (context, state) { <= error appears after this opening bracket
switch (state.runtimeType) {
case OnSignInScreenState:
return const SignInScreen();
case OnSignUpScreenState:
return const SignUpScreen();
default:
const SignInScreen();
break;
}
},
),
Flutter doctor returns this: Flutter 医生返回:
flutter doctor -v
[√] Flutter (Channel stable, 3.3.10, on Microsoft Windows [Version 10.0.22621.1105],
locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.1)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2022 17.4.4)
[!] Android Studio (version 2022.1)
• Android Studio at
C:\Users\user\AppData\Local\JetBrains\Toolbox\apps\AndroidStudio\ch-0\221.6008.13.2
211.9477386
• Flutter plugin version 71.2.4
• Dart plugin version 221.6096
X Unable to find bundled Java version.
• Try updating or re-installing Android Studio.
[√] VS Code
[√] Connected device (3 available)
[√] HTTP Host Availability
! Doctor found issues in 1 category.
If I check for Java I get this:如果我检查 Java 我得到这个:
java -v Unrecognized option: -v Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. PS C:\Users\user> java --version java 19.0.2 2023-01-17 Java(TM) SE Runtime Environment (build 19.0.2+7-44) Java HotSpot(TM) 64-Bit Server VM (build 19.0.2+7-44, mixed mode, sharing)
In default state you do not add return before "const SingInScreen();"默认情况下 state 你不在“const SingInScreen();”之前添加 return
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