ERROR:flutter/lib/ui/ui_dart_state.cc(199) Unhandled Exception: Null check operator used on a null value

Question

I am trying to generate through injectable, I done flutter clean also it won't work, I am using stable version flutter 2.2.2, I am facing null check error on this line of code

this code is throwing error

SharedPreferences.getInstance();

also this code

   @module
    abstract class ThemeModule {
      @preResolve
      Future<SharedPreferences> get prefs async =>
           await SharedPreferences.getInstance();
    }

Error Stack

E/flutter (27063): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: Null check operator used on a null value
E/flutter (27063): #0      MethodChannel.binaryMessenger
package:flutter/…/services/platform_channel.dart:142
E/flutter (27063): #1      MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:148
E/flutter (27063): #2      MethodChannel.invokeMethod
package:flutter/…/services/platform_channel.dart:331
E/flutter (27063): #3      MethodChannel.invokeMapMethod
package:flutter/…/services/platform_channel.dart:358
E/flutter (27063): #4      MethodChannelSharedPreferencesStore.getAll
package:shared_preferences_platform_interface/method_channel_shared_preferences.dart:44
E/flutter (27063): #5      SharedPreferences._getSharedPreferencesMap
package:shared_preferences/shared_preferences.dart:180
E/flutter (27063): #6      SharedPreferences.getInstance
package:shared_preferences/shared_preferences.dart:56
E/flutter (27063): #7      main
package:financial/main.dart:12
E/flutter (27063): #8      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:142:25)
E/flutter (27063): #9      _rootRun (dart:async/zone.dart:1354:13)
E/flutter (27063): #10     _CustomZone.run (dart:async/zone.dart:1258:19)
E/flutter (27063): #11     _runZoned (dart:async/zone.dart:1789:10)
E/flutter (27063): #12     runZonedGuarded (dart:async/zone.dart:1777:12)
E/flutter (27063): #13     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:138:5)
E/flutter (27063): #14     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:283:19)
E/flutter (27063): #15     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)

Answer 1

I have the same issue and the solution is adding WidgetsFlutterBinding.ensureInitialized() in main function before run app:

Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
// init your dependency injection here
runApp(MyApp());}

From the docs:

Returns an instance of the WidgetsBinding, creating and initializing it if necessary. If one is created, it will be a WidgetsFlutterBinding. If one was previously initialized, then it will at least implement WidgetsBinding.

You only need to call this method if you need the binding to be initialized before calling runApp.

Answer 2

I also ran into that problem. However, the answer from @badasz was not a solution, because the exception disussed in the github issue was a completely different one. In my case, i ran the codeSharedPreferences.getInstance() before i called runApp(Widget app). That led to the given error.

Answer 3

Instead of this

void main() {
  
  // qrCode.make();
  SharedPreferences.getInstance();
 Firebase.initializeApp();
  // FirebaseApp defaultApp = Firebase.app();
  runApp(const MyApp());
}

Add like this

You must add WidgetsFlutterBinding.ensureInitialized(); starting of main method

    Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // qrCode.make();

  FirebaseApp app = await Firebase.initializeApp();
  // FirebaseApp defaultApp = Firebase.app();
  runApp(const MyApp());
}

Reason: This library depends on the native library(android ,ios etc platofrm). Make sure that you have an instance of the WidgetsBinding, which is required to use platform channels to call the native code.