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https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466661
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Jacob Kjome commented on BEANUTILS-268:
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My point about the comparators was that the statement implies that
BeanComparator's default internal comparator doesn't deal with null values and
that one would need to be provided that does if the beans in question might
return null for their properties. Maybe I misinterpreted, but there's no point
in stating it the way it is stated if BeanComparator's default internal
comparator does, in fact, deal with null values. Because in that case, it's
not a necessity to provide a custom comparator to the constructor. Instead, it
should read something like...
"Custom comparators should deal with the possibility of null values returned by
bean properties or risk a NullPointerException"
The above is more to the point and implies that BeanComparator's default
internal comparator deals with null bean property values, which really ought to
be the case, especially in a library that is supposed to be non-brittle....
But then again, after looking at the code, ComparableComparator does *not* deal
with null values. And that's the reason for the NullPointerException I'm
getting. Of course the error message could have been better to point that out
in the first place. I see it has been address in the latest version.
I guess the way to deal with null values is to use the commons-collections
NullComparator. And I suppose when using the ReverseComparator, I'd need to
provide it with the NullComparator in order for it to avoid
NullPointerExceptions. Ok, I think I get it.
Closing as invalid.
Jake
> BeanComparator.compare() doesn't can't handle null values returned by bean
> properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values.
> BeanComparator appears to fail with a NullPointerException. It's difficult
> to tell exactly where because the exception thrown is a ClassCastException
> with a message of e.toString(), so all I know is that a NullPointerException
> happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object)
> method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the
> problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal
> testcase, I'll see if I can narrow down the exception to a particular piece
> of code. In any case, there's no reason why a bean shouldn't be allowed to
> return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed
> to not return null. For instance, if I have a getter called getMyValue(), I
> create a corresponding method called getMyValueNotNul(). I have to take care
> with the value it returns, though. The position in a sort for a null value
> would be different than a literal empty String. So, depending on the Object
> type, I have to make up values which will either come before all other
> non-null values or after all other non-null values (I don't recall what the
> natural order of null values are; whether they come first or last. I know
> when ordering on a SQLcolumn, null values show up last. Hopefully that
> behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
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