Non urgent question on https://bugs.openjdk.java.net/browse/JDK-4834738 (Adding which Object is null to an NPE) (original) (raw)

Martijn Verburg martijnverburg at gmail.com
Mon Feb 27 13:06:08 UTC 2017

Hi David,

Thanks for the explanation, much appreciated!

Cheers, Martijn

On 27 February 2017 at 12:45, David Holmes <david.holmes at oracle.com> wrote:

Hi Martijn,

On 27/02/2017 10:03 PM, Martijn Verburg wrote:

Hi all,

The topic of adding more useful information to an NPE came up on the Java Champions list and after some digging we discovered some implementations elsewhere (SAP VM for example) and some historical conversations / issues. https://bugs.openjdk.java.net/browse/JDK-4834738 http://mail.openjdk.java.net/pipermail/hotspot-dev/2014-April/013535.html As I state in that linked topic that request was almost the inverse of other requests in this area - it wanted to report the method invoked on the null reference, whereas other requests were seeking more information on where the null arose eg in: a().b().c(); which invocation produced the NPE. But thinking about it again, perhaps reporting the member access that triggered the NPE is the most generally useful information to provide. The bug is listed as won't fix but didn't have any explanation added to it as to why. Is it just a case that the JIT and/or other mechanisms strips away that sort of information at runtime? The bug was closed as "won't fix" as part of a general cleanup up of old issues for which there are no active plans to address the issue. As I've commented in some of the issues where this was raised (and they are all quite old) there is a general lack of context available to give a meaningful error message about the NPE. Cheers, David Cheers, Martijn

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