On 2/12/20 2:04 PM, fo...@univ-mlv.fr wrote:
I don't disagree with the fact that having the index may help,
I disagree with the fact that chaining the IOOBE to the NSEE is the right way
to expose that index, crafting an error message with the index is IMO a better
idea because you have no idea if the exception thrown by all implementation of
List.get() will provide this index (and only this index).
It /seems/ like AbstractList has enough information to do the checks itself and
to formuate a reasonable error message, but it really doesn't. It does need to
delegate to the subclass's get() implementation to do the actual work. The get()
method has only two choices: it can return a valid element, or it can throw
IOOBE. AbstractList can guess at why get() failed, but the knowledge of that
belongs to the subclass, and it's the subclass's responsibility to put that
information into the IOOBE.
Of course it's possible that some subclass hasn't provided useful information in
the exception, but that shouldn't be a reason to penalize subclasses that have
done so.
It depends how List.get() is implemented, if there is a bound check before
accessing the value in the implementation, you have the same issue, one turtle
down :)
It's a subclass implementation choice as to whether it wants to do a bounds
check and throw explicitly or to let the VM generate the exception implicitly.
Either way results in an IOOBE (or some subtype). Which of these is done is
irrelevant to AbstractList; all it knows is that get() reported an error by
throwing an exception of this type, so it should be chained into the resulting NSEE.
s'marks
s'marks
Rémi
On 2/5/20 2:05 PM, Remi Forax wrote:
Stuart, Martin, Kiran,
I think this "bug" should not be fixed because it's one of the cases where
providing more information is actually bad from a user POV.
The current code throws NoSuchElementException when the iterator reach the end
so from the user POV, this is the right exception because of the right issue,
so from the user POV there is no need to change the actual code.
If we chain the exception,
- it's less clear from a user POV
- the user may think that there is an error in the AbstractList implementation
but it's not the case, it's just that AbstractList iterators next method is
implemented weirdly, it prefers to go out of bound instead of checking the
bound.
I'm okay with NoSuchElementException having a new constructor that takes a
chained exception but i really think that in this specific case, it's a bad
idea(TM) to use it to propagate an exception to the user that it should not
care about.
BTW, perhaps, those method next() should be re-written to test the bound instead
of catching the IOOBE because i'm not sure this "optimization" make sense
nowadays.
regards,
Rémi
----- Mail original -----
De: "Kiran Ravikumar" <kiran.sidhartha.raviku...@oracle.com>
À: "core-libs-dev" <core-libs-dev@openjdk.java.net>
Envoyé: Mercredi 5 Février 2020 20:49:09
Objet: Re: RFR [15] 8161558: ListIterator should not discard cause on exception
Thanks Stuart and Martin,
Here is an updated webrev with the changes.
http://cr.openjdk.java.net/~kravikumar/8161558/webrev.01/
JBS: https://bugs.openjdk.java.net/browse/JDK-8161558
Thanks,
Kiran
On 15/01/2020 12:46, Martin Buchholz wrote:
Hi Kiran,
Looks good to me, but I always nitpick ...
Stray semicolon?
var iterator = list.listIterator(list.size());; // position at end
I would have documented whitebox test assumptions: that nCopies
iterators are implemented via AbstractList, and that
AbstractList's list iterator inherits behavior from iterator.
I probably would have added a plain iterator test, and might have
refactored the code that tests the exception.
On Wed, Jan 15, 2020 at 4:07 AM Kiran Ravikumar
<kiran.sidhartha.raviku...@oracle.com
<mailto:kiran.sidhartha.raviku...@oracle.com>> wrote:
Hi Guys,
Could someone please review my fix to add missing standard
constructor
overloads to NoSuchElementException class and update the AbstractList
class to use them.
A CSR was filed and approved. Along with the code change a new
test is
added to verify the behavior.
Please find the webrev at -
http://cr.openjdk.java.net/~kravikumar/8161558/webrev.00/
JBS: https://bugs.openjdk.java.net/browse/JDK-8161558
Thanks,
Kiran
