Questions tagged [non-nullable]
232 questions
4
votes
2 answers
What are the differences between null analysis annotations packages?
The question Which @NotNull Java annotation should I use? is outdated and somewhat opinion based. Since then Java 8 came, along with newer IDEs.
While Java 8 allows type annotations by integration of JSR 308, it does not come with any. From JSR 308…
user1803551
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4
votes
3 answers
Android: NullPointerException despite @NonNull
I'm using annotations to ensure that parameter will be not null, assuming this would cause compiler check.
public @Nullable ApplicationAccount accountForKey(@NonNull String key) {
return accounts.get(key);
}
However, by running this code I…
Arnie Schwarzvogel
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4
votes
1 answer
How to use Objective-C __nonnull in a backwards-compatible way?
Xcode has recently added __nonnull, __nullable, etc. attributes. However, they're not supported by older versions of clang and other compilers.
How can I use these attributes in a compatible way?
I hoped something like this would work:
#ifndef…
Kornel
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- 309
4
votes
0 answers
"Value '' could not be converted." error when clearing ComboBox selection
I am trying to clear the selection in a ComboBox but get an error
"Value '' could not be converted."
The ComboBox's ItemSource is bound to a key-value pair list. The SelectedValue is the Key and the DisplayMemberPath is bound to the Value.
If…
TechBang
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4
votes
2 answers
Is it possible to define a "not Nullable" constraint in a C# generic method?
In C#, the Nullable type does not satisfy the where struct generic constraint (while AFAK this is techically a struct). This can be used to specify that the generic argument has to be a non-nullable value type :
T DoSomething() where T :…
tigrou
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4
votes
1 answer
Django 1.7: Makemigration: non-nullable field
I am trying to use django-orderedmodel (https://github.com/kirelagin/django-orderedmodel) in my project.
Running makemigrations doesn't work:
You are trying to add a non-nullable field 'order' to slide without a default; we can't do that (the…
cgwid
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4
votes
2 answers
Eclipse null type safety is wrong on return value
Eclipse seems to do wrong analisys , method test1 is ok, but method test2 give the error:
Null type safety: The expression of type String needs unchecked conversion to conform to @NonNull
public class TestCase {
public Object o;
@NonNull
…
user2735261
- 71
- 3
3
votes
2 answers
Is it possible in C# to write an implicit conversion operator for both nullable and non-nullable values?
I am trying to write an Alias class which enables me to:
int n = new Count(1);
That is, it encapsulates an int in this case as a Count, which gives some type safety and domain meaning, while it automatically converts back to the underlying…
Thomas Eyde
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3
votes
2 answers
Can't assign to NonNullable even though I checked that value is defined
Trying to reach peak TypeScript performance I'm currently getting into some of the niche areas of the language, and there's something I don't get.
With strict-null-checks and strict mode and that stuff enabled, I don't understand why this code gives…
NoBullsh1t
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3
votes
4 answers
The parameter 'id' can't have a value of 'null' because of its type, but the implicit default value is 'null'
I am following a Flutter tutorial that has such a following code, but code doesn't work on my computer, and I don't know how to fix it:
import 'package:flutter/foundation.dart';
class CartItem {
final String id;
CartItem({
@required…
user11874694
3
votes
1 answer
EF Core conversion and non nullable type converted to a nullable primitive
I have a class MyClass that has a non nullable property Maybe MyMproperty.
#nullable enable
public class MyClass
{
public long Id { get; set; }
public Maybe MyProperty { get; set; }
}
#nullable restore
I declare and use en EF…
François
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3
votes
2 answers
C# Compiler's null state static analysis when validating objects
I have enabled Nullable check in my project and in a lot of places in the code I check input object and its properties and throw exception if something is wrong. But if everything is all right then I'm certain that input object is not null. Is there…
Frodo Baggins
- 51
- 5
3
votes
1 answer
Are there any reasons not to always use the non-nullable reference types of C# 8.0?
Context
C# 8.0 has this features of non-nullable reference types.
string notNull = "Hello";
string? nullable = default;
notNull = nullable!; // null forgiveness
Question
What reasons are there to not always enable non-nullability in the *.csproj…
Lernkurve
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3
votes
1 answer
Whats wrong with non nullable objects?
I have been looking at DbC lately and Spec# which seem to have support for non nullable objects. Unfortunately Spec# seem to have been abandoned.
Spec# seemed to have lots of nice language features built in so why was it abandoned?
Would there be…
terjetyl
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3
votes
1 answer
Are Objective-C function results nonnull by default?
In this thread on implementing a UITextInput delegate method, the poster says that when they run static analysis on their code, they get an error on this function:
- (NSArray *)selectionRectsForRange:(UITextRange *)range
{
return nil;
}
The…
Duncan C
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