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Questions tagged [dart-null-safety]

Tag for questions regarding Dart code involving non-nullable types. This should only be used in combination with the Dart tag.

With the announcement of null safety, there are two types of Dart code:

  • Code with only nullable types.
  • Code with null safety enabled → with non-nullable types.

The tag covers questions involving the latter. Question with this tag should be subset of .

1185 questions
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_TypeError (type 'Null' is not a subtype of type 'FutureOr')

Have recently installed Flutter null safety and having fixed most of the code I am having trouble with an API call. It returns _TypeError (type 'Null' is not a subtype of type 'FutureOr') I haven't found a SO answer that seems to line up…
al246
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I am trying to save the notification title and body using shared preference but i am unable to

#I am trying to save the notification title and body locally and fetch the title and body inside my app to show all the sent notification in a listview but i am unable to #this is the code i am running this code in my main.dart inside initstate and…
Saurav
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The function call is not returning null but still giving "null" to be returned error

I'm migrating my old version flutter code to latest version with null safety feature. In a function call I am getting the error "The body might complete normally, causing 'null' to be returned, but the return type is a potentially non-nullable…
Dev94
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The method '[]' was called on null. Receiver: null Tried calling: []("main") console error

Hi i am working on a weather app i learnt from a course, everything was working fine till i start with the refactoring and it just got complicated the code show no error but when i hot restart the app it crash showing The method '[]' was called on…
Olamilekan Adeyemi
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Flutter Null Safety and Firebase authentication error

I am using flutter and firebase for my app. I don't know why I am getting error in below code. With degrade version of flutter(Without null safety) it is working fine but after migrating over null safety, I am facing problem here. class…
Harry
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Error: The argument type 'User?' can't be assigned to the parameter type 'User' because 'User?' is nullable and 'User' isn't. *(NullSafety)*

I'm taking a course for Flutter and I think the course is a bit old, I'm trying to upgrade an old code to null safety, but since I'm just starting to learn null safety, I'm encountering errors and I couldn't figure out why, I would be glad if you…
Levent Demirci
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Dart check if many variable is null

Hello im new in dart language, is someone can help me to write this condition better, it works but it's a lot repetitive and i feel theres a better ways to write it : if (var1 != null || var2 != null || var3 != null || var4 != null || var5 !=…
Pierre Huret
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Dart null safety !. vs ?-

what is the difference exactly between String id = folderInfo!.first.id; //this works and String id = folderInfo?.first.id; //this is an error I know ?. returns null when the value object is null but what does the !. return?
Paul Cbt
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json.decode to List> issue in flutter

snap shot from the code Hello I am trying to get Data from API And put it inside List> I use a several ways but they doesn't work In the image the data saved in the variable but when i use foreach it ignore the index 0 I try to…
Muhammed Attas
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flutter geolocator: ^8.0.1 not working properly

I was trying to use geolocator in my flutter project but i keep getting the following error code when i restart the app: This is my flutter code below: import 'package:flutter/material.dart'; import 'package:geolocator/geolocator.dart'; class…
Olamilekan Adeyemi
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+ isn't defined for the type 'Object

I keep getting this error => "The operator '+' isn't defined for the type 'Object'. (view docs). Try defining the operator '+'." How could I define it? import 'dart:math'; bool isArmstrongNumber(int number) { var numberString =…
Carlos
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type 'Null' is not a subtype of type 'AuthViewModel' in type cast

Im trying to build a Google sign in page and i got this error : type 'Null' is not a subtype of type 'AuthViewModel' in type cast , i dont know what to doh ere I tried to solve it but nothing worked and vscode didnt thro any errors till i run the…
Yousif 304
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Why is Flutter building without sound null safety

My pubspec.yaml has environment: sdk: '>=2.15.0-116.0.dev <3.0.0' When I run flutter build appbundle/apk it prints Building without sound null safety For more information see https://dart.dev/null-safety/unsound-null-safety Running Gradle task…
iDecode
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how to create draggable scrolling bottom sheet inside google maps scaffold in flutter?

I want to create a draggable scrolling bottom sheet like this! here is the design there will be a button on the top left to go back, there will be a button on the top left to go back, and there is a draggable bottom sheet should I use the…
Max
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I have a problem in my flutter app. For some reason I can't run any of my flutter files. Every time I try to run it keeps giving me an error message

C:\Users\omar\src\flutter.pub-cache\hosted\pub.dartlang.org\geolocator_android-3.0.1\android\src\main\java\com\baseflow\geolocator\location\LocationMapper.java:29: error: cannot find symbol if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S)…
Omar Mohamed
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