Questions tagged [nullability]
The nullability tag has no usage guidance.
nullability
32
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Issue with nullability specifiers in Xcode when developing Flutter app
I'm developing a Flutter application and encountering an issue with nullability specifiers in Xcode. Specifically, I have methods in my Objective-C files where Xcode is reporting conflicts with ...
- 11
1
vote
1
answer
115
views
How to avoid the "type test cannot be checked" waring in pattern matches of nullable types?
The intention of the following method is to remove null values
def filterOutNulls[T](items: Iterable[T | Null]): Iterable[T] =
items.collect { case element: T => element }
The code works at ...
- 1,216
0
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1
answer
71
views
How to get unknown nullability function return type in Kotlin?
What I want to achieve is to get Any! return type from function, so I can determine myself whether to handle nullability or not. The only way to get this type I found is to call a Java function.
For ...
3
votes
1
answer
115
views
how to force that a generic method never returns a null value
In the following example:
async Task Main()
{
// data can actually NEVER be null, but here it is of type Response?
var data1 = GetResponseData();
var data2 = await GetResponseDataAsync();
}...
- 51
-2
votes
1
answer
41
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Kotlin - Issue with Elvis operator
Why the below code gives error? It should print "Bonjour" as output
fun main()
{
var a:String? = null
var b:String? = "Hello"
var result1 = a?:"Gracias"
...
- 7
2
votes
4
answers
342
views
Is it possible to create a String extension `isEmptyOrNull` in dart?
First off let's define some criteria for this extension:
It should return true if the object is null or an empty string.
I should be able to use it on a chained nullable object.
I should not have to ...
- 3,910
0
votes
1
answer
66
views
Filtering for Non-Nullable Strings in C# Lists
I'm trying to create a list of non-nullable string values by filtering, but I always end up with a list of nullable strings.
var list = new List<string?> {"Cars", "Audi", &...
- 9
1
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1
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81
views
Nullability Check: Difference between literals and objects, or: "Why does "if(is null) [..]" work for object? but not for int?/long?/.. ?"
I stumbled across an interesting issue where I do not have any explanation for, hoping someone could explain.
When dealing with nullable objects (pseudo) code like the following works (Note: working ...
- 33
-1
votes
1
answer
110
views
Vector of 'nullable' HashMaps in rust
I am finding extremely difficult to deal with vectors of HashMaps in rust. I want to use vectors of HashMaps as an implementation of a sparse matrix container according to constraints that I, ...
- 202
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224
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Nullability of generic type arguments
So far I've worked with Nullable.GetUnderlyingType and even NullabilityInfo.WriteState to determine the nullability of types. This worked well - sometimes.
I'd like to know the nullability of the ...
- 131
2
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1
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149
views
Making the C# compiler aware that a null-oblivious method may return null?
AutoMapper's T IMapper.Map<T>(object) is null-oblivious for historical reasons. If you pass null, the result is null. The C# compiler does not warn about the possible null return when returning ...
- 10.2k
0
votes
1
answer
394
views
Stop nullability warnings from entity framework queries that include nullable navigation properties
Consider an entity framework core model with the following two entities:
public class RiskAssessment {
public string Title { get; set; } = string.Empty;
public Guid? ActivityID { get; set; }
...
- 1,659
0
votes
2
answers
573
views
What is the difference between LiveData<String>() and LiveData<String?>()
I am new to LiveData thing in general and I am having a hard time understanding the difference between LiveData<String>() and LiveData<String?>(). I used them interchangeably and nothing ...
0
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1
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42
views
Is there a way to indicate to C# nullability analysis that an instance variable will never be null after a certain method runs?
I've got a class with an instance var that can be null, and that class has a method that initializes that var. Broadly simplified, it looks a bit like this
#nullable enable
class SomeClass
{
...
- 1,073
0
votes
1
answer
316
views
Make the Intellisense nullability warning conditional, similar to Dictionary<string, string>.TryGetValue(...)
In Visual Studio, Intellisense is smart enough to know that the 'out' variable value in Dictionary<string, string>.TryGetValue(string key, out string value) is not null if the method returns ...
- 3,295