Thanks for the answers, it's becoming more clear.
The possibility suggested by Kalle makes sense, however I made some test about
it and I don't think it's the cause of my problem. This grid column was being
sorted without exceptions with Java 7 + Tapestry 5.3.7, plus I checked and none
of the values in the column is null. I have also tested calling Arrays.sort
with some null elements and it throws a null pointer both with Java 7 and Java
8.
My problem has most probably to do with the fact that that column is not part
of the grid data source, as Cezary suggested, and it was so also when we were
using Java 7.
About Cezary's hypothesis, I think my problem is definitely in that area, but
there is probably also something going on related to the different Tapestry
version because the column was defined in the same way when using 5.3.7 and in
that case there was no exception.
The column is defined like this:
- In the page template, one param of the grid tag is
t:add="prop:gridAdd"
- In the page Java code, there is the corresponding
public String getGridAdd() {
return " myColumn1, myColumn2, myColumn3, myColumn4";
}
where let's say that "myColumn3" is the column whose sorting fails.
- In the page template, within the t:grid tag there is the definition of the
customized content of that column:
<p: myColumn3Cell>${ myColumn3}</p: myColumn3Cell>
- In the page Java code, there is the method returning the value for that
column:
public String getMyColumn3()
{
return aStringThatIsNeverNull;
}
So I'm trying to find out if this way of defining my column is not right in
5.3.8 although it was not failing in 5.3.7, in order to rectify it.
-----Original Message-----
From: Cezary Biernacki [mailto:[email protected]]
Sent: Monday, June 27, 2016 18:10
To: Tapestry users <[email protected]>
Subject: Re: Null pointer on sort with 5.3.8 that didn't occur with 5.3.7
Your stack trace seems to indicate that conduit (a mechanism connecting
Tapestry with a column) is not available. It can happen if the column is
manually added to the model. Was the column sortable with Tapestry 5.3.7?
How is this column defined?
Best regards,
Cezary
On Mon, Jun 27, 2016 at 4:43 PM, Davide Vecchi <[email protected]> wrote:
> Hi everybody
>
> For now I cannot post code to reproduce this problem because it only
> occurs with one columns of a specific grid from a big application and
> so far I wasn't able to extract the code to reproduce the error into a
> runnable example. But after posting this I will keep trying and if I
> manage I will post that.
>
> We migrated this web application from Java 1.7 + Tapestry 5.3.7 to
> Java
> 1.8 with Tapestry 5.3.8 .
>
> Clicking on the column header of this column - which contains String
> values - causes the exception below.
>
> While I'm investigating this error I was wondering if someone is aware
> of differences in the grid sorting of Tapestry 5.3.8 that might cause
> it to throw a null-pointer where Tapestry 5.3.7 wouldn't (and maybe
> should; it's likely that there is a mistake of mine that was somehow
> being "forgiven" by 5.3.7).
>
> Stacktrace:
>
> java.lang.NullPointerException
> ?
> org.apache.tapestry5.internal.grid.CollectionGridDataSource$2.compare(
> CollectionGridDataSource.java:78)
> ?
> org.apache.tapestry5.internal.grid.CollectionGridDataSource$3.compare(
> CollectionGridDataSource.java:91) ?
> java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
> ? java.util.TimSort.sort(TimSort.java:234)
> ? java.util.Arrays.sort(Arrays.java:1512)
> ? java.util.ArrayList.sort(ArrayList.java:1454)
> ? java.util.Collections.sort(Collections.java:175)
> ?
> org.apache.tapestry5.internal.grid.CollectionGridDataSource.prepare(Co
> llectionGridDataSource.java:97)
> ?
> my.package.gui.tapestry.components.AMCGridEmbedded$CachingDataSource.p
> repare(AMCGridEmbedded.java:853)
> ?
> my.package.gui.tapestry.components.AMCGridEmbedded.setupDataSource(AMC
> GridEmbedded.java:1174)
> ?
> my.package.gui.tapestry.components.AMCGridEmbedded.setupRender(AMCGrid
> Embedded.java:655)
> ?
> my.package.gui.tapestry.components.AMCGridEmbedded.advised$setupRender
> _1a14d3f8fd924(AMCGridEmbedded.java)
> ?
> my.package.gui.tapestry.components.AMCGridEmbedded$Invocation_setupRen
> der_1a14d3f8fd923.proceedToAdvisedMethod(Unknown
> Source)
> ?
> org.apache.tapestry5.internal.plastic.AbstractMethodInvocation.proceed(AbstractMethodInvocation.java:84)
> ? ....
> ? ....
>
>
