Useful message about NullPointerException

[kedar mhaswade]

On Mon, Jan 26, 2015 at 11:20 AM, Bernd Eckenfels <ecki at zusammenkunft.net>
wrote:

> Am Wed, 21 Jan 2015 05:45:08 -0700 (MST)
> schrieb pike <pike630 at hotmail.com>:
>
> > We frequently see NullPointerException in our logs. It's really a big
> > headache when we see a NullPointerException and it is encapsulated in
> > another exception as we don't know which object is null and it is
> > throwing an Exception. Is there any way we can get to know the object
> > type or the object variable name where the object is null and it is
> > throwing a NullPointerException? i.e, instead of just saying there is
> > a NullPointerException, can we add some friendly message?
>
> Note that if you keep the stack information in an exception it points
> (most of the time) exactly to the location where the null access
> happens.
>
>
​Maybe the objects in question are not talking only to their immediate
friends <https://en.wikipedia.org/wiki/Law_of_Demeter>?
This happens when we tend to do something like *a.getB().getC()* and we
can't tell by looking at the NPE stack trace (which works on lines of
source code) if *a* was null or what *a.getB()* returned was null.

I can imagine it is rather hard for the VM to add more informations.
> Your best bet is to avoid the NPEs and log the exceptions properly.


> Gruss
> Bernd
>