Question

My program crashes due to a null pointer exception.

Snip of Stack Trace:

java.lang.NullPointerException
at com.my.GRTRecTimeSortComparator.compare(SourceFile:15)

That’s well and good. But my problem is that line 15 is the class declaration:

15 public class GRTRecTimeSortComparator   implements Comparator<GRTRecord> {
16    @Override
17    public int compare(GRTRecord rec1, GRTRecord rec2) {
18      
19      int returnVal=rec1.getRecordCalendar().compareTo(rec2.getRecordCalendar());
20        return returnVal;
21    }
22}

It’s calling out the Compare function, but I don’t see an issue with that either. Every record has a Unique Calendar assigned to it as well.

Any ideas? What have I done wrong here?

Edit: in response to queries:

No, there is nothing strange about the class itself, other than the fact I wrote it.

I AM using Proguard. Maybe the Obfuscation is replacing things incorrectly?

I’m writing up tests for the records right now. They SHOULDN’T be null, nor should the Calendars; I use them immediately before, and get good results.

Maybe I’m just passing the ArrayList incorrectly.

EDIT 2:

Logging lines inserted into the class never get run.
No matter what I add or do to the class, the null pointer always resolves to the class declaration line.

Removed Proguard Obfuscation, and still no dice.

I’m REALLY frustrated.

Edit 3:

For Future Users:

Proguard ruins your stack trace. That was the cause of the Above. Remove proguard if you run into issues.

The CAUSE was actually a corrupted record in the dataset.

Answer 1

I strongly suspect that the debug information is just out of sync. Put logging into your compare method. I would log (in order):

• rec1
• rec2
• rec1.getRecordCalendar()
• rec2.getRecordCalendar()

If this isn’t the problem, is there anything “odd” about the class in any other way? For example:

• Are you using Hibernate or something similar which may be creating proxies for you?
• Is this an inner class?