fix screen adapter

example/lib/main.dart

@@ -9,44 +9,28 @@ void main() {
 class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
-    ScreenUtil.init(context,
-        designSize: Size(750, 1334), allowFontScaling: false);
     return MaterialApp(
       title: 'Flutter Demo',
       theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // Try running your application with "flutter run". You'll see the
-        // application has a blue toolbar. Then, without quitting the app, try
-        // changing the primarySwatch below to Colors.green and then invoke
-        // "hot reload" (press "r" in the console where you ran "flutter run",
-        // or simply save your changes to "hot reload" in a Flutter IDE).
-        // Notice that the counter didn't reset back to zero; the application
-        // is not restarted.
         primarySwatch: Colors.blue,
-        // This makes the visual density adapt to the platform that you run
-        // the app on. For desktop platforms, the controls will be smaller and
-        // closer together (more dense) than on mobile platforms.
         visualDensity: VisualDensity.adaptivePlatformDensity,
       ),
-      home: MyHomePage(title: 'Flutter Demo Home Page'),
+      home: _ScreenAdapter(),
     );
   }
 }
 
-class MyHomePage extends StatefulWidget {
+class _ScreenAdapter extends StatelessWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  @override
-
+  Widget build(BuildContext context) {
-  // This widget is the home page of your application. It is stateful, meaning
+    ScreenUtil.init(context,
-  // that it has a State object (defined below) that contains fields that affect
+        designSize: Size(750, 1334), allowFontScaling: false);
-  // how it looks.
+    return MyHomePage();
-
+  }
-  // This class is the configuration for the state. It holds the values (in this
+}
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
 
-  final String title;
+class MyHomePage extends StatefulWidget {
+  MyHomePage({Key key}) : super(key: key);
 
   @override
   _MyHomePageState createState() => _MyHomePageState();
@@ -57,7 +41,7 @@ class _MyHomePageState extends State<MyHomePage> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text(widget.title),
+        title: Text('title'),
       ),
       body: ListView(
         children: [