Re: [jdt-core-dev] Can IParent.getChildren() return null

[Markus Keller <markus_keller@xxxxxxxxxx>]

> I see that IParent.getChildren() is implemented in BinaryType, which
> returns ClassFileInfo.binaryChildren.
> Now ClassFileInfo.binaryChildren seems to be initialized with a null.
> 
> Does that mean that everywhere getChildren() is used, there needs to
> be a null check?

IParent.getChildren() is API and guarantees that it does not return null, 
so adding null checks at references to that method would be wrong. You 
should only write your code against the API, not against a particular 
implementation. And if the API is broken, please file a bug.

A better question is: Why is the implementation sound, i.e. does it really 
guarantee the API contract?

AFACIS, it's fine: BinaryType#getChildren() calls getClassFileInfo() 
before accessing the field. If you follow the implementation, you see that 
JavaElement#getElementInfo(IProgressMonitor) either gets the initialized 
info from the model manager, or it calls openWhenClosed(..), which calls 
generateInfos(..), which calls Openable#generateInfos(..), which calls 
ClassFile#buildStructure(..), which calls 
ClassFileInfo#readBinaryChildren(..), which initializes 
ClassFileInfo#binaryChildren.

HTH,
Markus