Use Objects.requireNonNull(Object) for that. Checks that the specified object reference is not null. This method is designed primarily for doing parameter validation in methods and constructors, […] In your case that would be: public void useObject(CustomObject customObject) { object = customObject.getObject(); Objects.requireNonNull(object); // throws NPE if object is null // do stuff with object } … Read more
Use nullable types: List<int, SomeStruct?> You can’t assign null to an element of the list because structs are value types, while null means an empty pointer, and so can only be assigned to reference type variables. Also note that List as you’re using it doesn’t exist in .NET! Perhaps you want Dictionary?
Well firstly, Nullable<T> is a struct, so there isn’t an object as such. You can’t call GetType(), as that will box the value (at which point you either get null and thus an exception, or a boxed non-nullable value and therefore not the type you want). (Boxing is what’s messing up your assertion here – … Read more
The direct answer, use the !! operator to assert that you trust a value is NOT null and therefore changing its type to the non null equivalent. A simple sample showing the assertion allowing the conversion (which applies to any nullable type, not just Int?) val nullableInt: Int? = 1 val nonNullableInt: Int = nullableInt!! … Read more
There are two things going on: 1) The compiler treats “null” not as a null reference but as a null value… the null value for whatever type it needs to convert to. In the case of a Nullable<T> it’s just the value which has False for the HasValue field/property. So if you have a variable … Read more
The point here is that int? i = null; does not create a variable i which is null, but (by performing an implicit cast) a Nullable<int> instance which does not have a value. This means the object/instance is not null (and as Nullable<T> is a struct/value type it actually can’t be null) and therefore has … Read more
Embeddable components (or composite elements, whatever you want to call them) usually contain more than one property and thus are mapped to more than one column. The entire component being null can therefore be treated in different ways; J2EE spec does not dictate one way or another. Hibernate considers component to be NULL if all … Read more
It is possible to use PropTypes.oneOf([null]).isRequired. It should allow null, and nothing else. You can combine that with any other type: PropTypes.oneOfType([ PropTypes.string.isRequired, PropTypes.oneOf([null]).isRequired, ]).isRequired Edit: I just had this prop type fail for me when given a null prop using prop-types 15.7.2, so I’m not sure this works anymore (if it ever did?). I … Read more
Re: your latest update: This is a bug in the nullable arithmetic optimizer. The nullable optimizer will remove the unnecessary conversion to int? when you do something like: short? s = null; int? x = s + 1; The unoptimized codegen does the equivalent of: short? s = null; int? x; int? temp = s.HasValue … Read more
The LINQ to DataSets chapter of LINQ in Action is a good read. One thing you’ll see is the Field<T> extension method, which is used as follows:- int? x = dr.Field<int?>( “Field” ); Or int y = dr.Field<int?>( “Field” ) ?? 0; Or var z = dr.Field<int?>( “Field” );