在使用不包含 MediaQuery 的上下文调用的 flutter MediaQuery.of() 中出现错误

Question

I didn't understand what the error is. I am returning a Scaffold widget. There are no syntax errors detected by visual studio code. I am getting an error while running the app.

void main() {
runApp(MyApp());
}

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
   appBar: AppBar(title: Text("here is my text")),
   body: Text(
     'No, we need bold strokes. We need this plan.',
     style: TextStyle(
         fontWeight: FontWeight.bold,
         color: Colors.blue.withOpacity(0.7),
         height: 1,
         fontSize: 20,
         decoration: TextDecoration.underline,
         decorationColor: Colors.green,
         decorationStyle: TextDecorationStyle.wavy,
         backgroundColor: Colors.red),
   ),
 );
}
}

If I wrap the scaffold widget in the material app it is working. Can anyone explain to me the reason?

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("here is my text")),
        body: Text(
          'No, we need bold strokes. We need this plan.',
          style: TextStyle(
              fontWeight: FontWeight.bold,
              color: Colors.blue.withOpacity(0.7),
              height: 1,
              fontSize: 20,
              decoration: TextDecoration.underline,
              decorationColor: Colors.green,
              decorationStyle: TextDecorationStyle.wavy,
              backgroundColor: Colors.red),
        ),
      ),
    );
  }
}

Answer 1

The top most widget must be wrapped in a MaterialApp widget. This is what generates the context chain that it's looking for.

Answer 2

Media Query is a property of MaterialApp so if you don't use the MaterialApp, you can't access media query. The proper way is to use it in your main class.