dart-null-safety Questions
2
Solved
Dart compiler does not understand that the variable can not be null when I use it inside an if (x != null) statement. It still requires to use conditional ? or null check ! operators to access one ...
Trefoil asked 22/4, 2022 at 8:49
2
This Dart official video states that Dart's so-called "sound null safety" is better than Kotlin's null safety design, because it can optimise the code based on whether a variable is decla...
Salsify asked 3/12, 2020 at 8:35
6
Solved
I don't really understand how required works. For example I've seen this code:
class Test{
final String x;
Test({
required this.x
});
factory Test.initial(){
return Test(x: "");
}...
Dedication asked 14/1, 2019 at 12:46
5
Solved
I had code similar to this example code (never mind that it makes no sense):
void foo(Map<int, String> myMap) {
String s = myMap[1];
}
The dart analyzer warns me about the line String s = m...
Specialize asked 10/12, 2020 at 13:53
4
Solved
Why List() constructor is not accessible after Dart's null safety?
// Compile time error: 'List' is deprecated and shouldn't be used.
// The default 'List' constructor isn't available when null saf...
Lapland asked 17/8, 2020 at 13:9
3
I want to create an app which has a TabBarView with two tabs. On the first Tab there is a Textfield and on the other tab there is a text widget which should display the text which you entered into ...
Doley asked 27/1, 2019 at 11:24
3
Solved
I've started getting a warning every time I create a new class.
Use key in widget constructors.
Prefer const with constant constructor.
and so on. Where these errors are coming from and how do...
Assentor asked 29/5, 2021 at 15:48
4
Solved
class StudentValidationMixin {
String validateFirstName(String value) {
if(value.length<2){
return 'İsim en az iki karakter olmalıdır';
}
}
}
The body might complete normally, causing 'nu...
Ruthven asked 9/7, 2021 at 19:48
1
Solved
I have a simple class like this:
class Restaurant{
final String id;
final String name;
List<Serving> servingList;
Restaurant({
required this.id,
required this.name,
this.servingList =...
Hennery asked 13/11, 2021 at 16:11
2
After upgrading to flutter 2.0.0 I can't build the app anymore. this is the output. My problem is I have heavy usage of libraries and a lot of them are not null safe and I can't upgrade all of my d...
Marcasite asked 4/3, 2021 at 8:22
4
Solved
I have this class which takes some parameters by using the factory constructor, if instance is null, a new object will be created; if it's not null, the value of instance will be returned so we alw...
Paoting asked 6/3, 2021 at 20:12
2
Solved
I often use .firstWhere((E element) -> bool) -> E in my project. When porting it to support null safety I couldn't cleanly handle a scenario when an element is not found in a List instance.
....
Amoebocyte asked 13/9, 2021 at 10:49
6
In dart sdk greater than 2.12.0 we are often using '?' to make sure that argument can have null values also, but how to convert datatype with ? to datatype without ? or vice versa. what can be the ...
Mishnah asked 11/5, 2021 at 23:22
2
Its a general question. Not coding related. Everywhere I follow flutter tutorials I see the simple variable declarations. But when I write the same code (I think because of updating) it requires to...
Optimism asked 28/8, 2021 at 15:14
2
I was learning flutter about year ago and now im coming back after a break but i counter a problem, it's probalby pretty simple but i dont really understand it.
Im following a tutorial on Flutter C...
Capriola asked 25/6, 2021 at 13:5
2
Solved
I have an object that extends Equatable and contains optional parameters. If I try to add that parameter into the props getter, I get an error The element type 'String?' can't be assigned to the li...
Vega asked 14/8, 2021 at 21:0
2
Solved
Before the null safety I could simply mock up the sendRequest(...) method like that:
void stubBaseRepositorySendRequestResponse(String response) {
when(baseRepository.sendRequest(onGetData: anyNa...
Sweeting asked 27/4, 2021 at 20:51
1
Solved
When I run "dart migrate" for enabling null-safety, it gives me following output.
Before migrating your package, we recommend ensuring that every library it
imports (either directly or i...
Rainstorm asked 6/7, 2021 at 4:17
4
Solved
I have migrated my Dart code to NNBD / Null Safety. Some of it looks like this:
class Foo {
String? _a;
void foo() {
if (_a != null) {
_a += 'a';
}
}
}
class Bar {
Bar() {
_a = 'a';
...
Hennery asked 26/12, 2020 at 13:39
1
Solved
I upgrade my flutter sdk to flutter 2.0.0. After updating sdk I have changed almost all libraries to null safety version:
environment:
sdk: '>=2.12.0 <3.0.0'
dependencies:
flutter:
sdk: f...
Leyes asked 4/3, 2021 at 11:40
4
Solved
After migrate to null-safety showing this error. What should I do now?
Widget chatMessages() {
return StreamBuilder(
stream: messageStream,
builder: (context, snapshot) {
return snapshot.hasDa...
Eligible asked 17/3, 2021 at 9:25
1
Solved
For my debut with Dart/Flutter I created a very simple demo app with a localized text within a Drawer. The app compiles and starts in the Android Emulator, but only to abort shortly after with the ...
Theophylline asked 27/5, 2021 at 13:35
2
Solved
While I know this may look like a duplicate with how many different posts there are about this error but I am getting this error for (which I assume) are different reasons on four different screens...
Lemmy asked 19/3, 2021 at 16:29
2
Solved
I declared a callback method inside a Stateful class like:
final void Function(int index)? onSelected;
MyBottomNavigationBar({@required this.onSelected});
and called using widget.onselected inside...
Tia asked 24/5, 2021 at 5:31
2
The following code does not compile with sound null safety because it is possible to pass null to the constructor which initializes a non-nullable field myString.
class MyClass {
String myString;
...
Arrogate asked 24/5, 2021 at 12:6
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