try-with-resources and null resource

[Bruce Chapman]

On 27/01/2011 4:53 a.m., Jesper Öqvist wrote:
> Rémi Forax wrote:
>> On 01/21/2011 07:24 PM, Paul Benedict wrote:
>>
>>> The NPE is more useful than the language silently doing nothing with a
>>> null pointer. While your idea is convenient, I believe it assumes too
>>> much. If anything, perhaps the language shouldn't allow an explicit
>>> null assignment in a try-with-resources block.
>>>
>> Hi Paul,
>> the null assignement is just an example. Perhaps, you prefer this one:
>>
>> 4. try(AutoCloseable c = getAnAutoCloseableThatMayBeNull()) {
>> 5.     // nothing
>> 6. }
>>
>> Rémi
>>
> I am concerned about the consistency between what the programmer expects
> and what the compiler produces.
>
> It seems to me that the following code should be legal, and execute
> without throwing an NPE:
>
> try (Resource r = null) {
>      r = new SomeResource();
> }

Jesper,

you missed the point that the resource variable is effectively final, so 
you are not allowed to assign another value to it later (that would 
cause another whole can of worms)


Bruce
> However with a null check in the try part of the try-with-resource
> statement, or an NPE, execution might not pass through the statement as
> the programmer expects it to.
>
> Jesper
>
>