[ERROR:flutter/lib/ui/ui_dart_state.cc(171)] Unhandled Exception: NoSuchMethodError: The getter 'modalBarrierDismissLabel' was called on null.

[siddheshjungade]

💬 Questions and Help

I am new to flutter I am facing bug App is working properly but alert box is not showing

ERROR:flutter/lib/ui/ui_dart_state.cc(171)] Unhandled Exception: NoSuchMethodError: The getter 'modalBarrierDismissLabel' was called on null.
E/flutter ( 9979): Receiver: null
E/flutter ( 9979): Tried calling: modalBarrierDismissLabel
E/flutter ( 9979): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
E/flutter ( 9979): #1 Alert.show (package:rflutter_alert/src/alert.dart:54:55)
E/flutter ( 9979): #2 _QuizzlerState.checkAnswer. (package:quizzler/main.dart:49:11)
E/flutter ( 9979): #3 State.setState (package:flutter/src/widgets/framework.dart:1244:30)
E/flutter ( 9979): #4 _QuizzlerState.checkAnswer (package:quizzler/main.dart:20:5)
E/flutter ( 9979): #5 _QuizzlerState.build. (package:quizzler/main.dart:116:23)
E/flutter ( 9979): #6 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:989:19)
E/flutter ( 9979): #7 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:1098:38)
E/flutter ( 9979): #8 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:183:24)
E/flutter ( 9979): #9 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:528:11)
E/flutter ( 9979): #10 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:287:5)
E/flutter ( 9979): #11 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:222:7)
E/flutter ( 9979): #12 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:476:9)
E/flutter ( 9979): #13 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:77:12)
E/flutter ( 9979): #14 PointerRouter._dispatchEventToRoutes. (package:flutter/src/gestures/pointer_router.dart:122:9)
E/flutter ( 9979): #15 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 9979): #16 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:120:18)
E/flutter ( 9979): #17 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:106:7)
E/flutter ( 9979): #18 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:219:19)
E/flutter ( 9979): #19 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:199:22)
E/flutter ( 9979): #20 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:157:7)
E/flutter ( 9979): #21 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:103:7)
E/flutter ( 9979): #22 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:87:7)
E/flutter ( 9979): #23 _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter ( 9979): #24 _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 9979): #25 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 9979): #26 _invoke1 (dart:ui/hooks.dart:265:10)
E/flutter ( 9979): #27 _dispatchPointerDataPacket (dart:ui/hooks.dart:174:5)
E/flutter ( 9979):

[siddheshjungade]

this is code

void checkAnswer(bool userPickedAns){
setState(() {
if(quizBrain.isFinish() == true){
print('allert');
Alert(
context: context,
type: AlertType.warning,
title: "RFLUTTER ALERT",
desc: "Flutter is more awesome with RFlutter Alert.",
buttons: [
DialogButton(
child: Text(
"FLAT",
style: TextStyle(color: Colors.white, fontSize: 20),
),
onPressed: () => Navigator.pop(context),
color: Color.fromRGBO(0, 179, 134, 1.0),
),
DialogButton(
child: Text(
"GRADIENT",
style: TextStyle(color: Colors.white, fontSize: 20),
),
onPressed: () => Navigator.pop(context),
gradient: LinearGradient(colors: [
Color.fromRGBO(116, 116, 191, 1.0),
Color.fromRGBO(52, 138, 199, 1.0)
]),
)
],
).show();

    quizBrain.reset();

    scoreKeeper = [];
  }
  else{
    if(quizBrain.getQuestionAns() == userPickedAns){
      scoreKeeper.add(
          Icon(
            Icons.check,
            color: Colors.green,
          )
      );
    }
    else{
      scoreKeeper.add(
          Icon(
            Icons.close,
            color: Colors.red,
          )
      );
    }
    quizBrain.nextQuestion();
  }

});

}

[renefloor]

Sorry for the late response, but this has nothing to do with flutter_cache_manager. For generic Flutter questions it is better to use StackOverflow.

But I also don't understand how Alert.show() would work within setState. You can have a look at the AlertDialog example to show dialogs: https://api.flutter.dev/flutter/material/AlertDialog-class.html