Odd stack trace

Question

I'm not expecting anybody to solve my problem (though it'd be nice if you could) - I just found this a bit wierd and thought I'd get a sanity check - its Friday, so maybe I'm going slightly crazy.
I've had a few occurances lately of the same stack trace on a live system; Although it always occurs in exactly the same piece of code, I haven't been able to systematically reproduce it, either in a development environment or on the live system.
It looks like this:
java.lang.NullPointerException
      at com.mycompany.mypackage.MyClass.myMethod(Compiled Code)
      at com.mycompany.mypackage.MyOtherClass.myOtherMethod(Compiled Code)
      at ...etc...Now, as far as I'm aware, that stack trace indicates that a NullPointerException occured somewhere inside a method called myMethod in the class com.mycompany.mypackage.MyClass
But (and here's the wierd bit), the relevant code in MyClass looks like this:
private Integer myInteger;
public Integer myMethod() {
  return myInteger;
}How can that possibly throw a NullPointerException ???
Am I wrong on what the stack trace is indicating? - I'm not aware of any formal specification of what exactly a stack trace means - in fact, the API docs say "The format of this information depends on the implementation", so I'm just going off experience...
Does anybody else find this a little wierd? Has anybody else seen it before?

Answer 1

The real location causing the thrown exception can be muddied by the JIT compiler. Try to run your program with Java in interpreted mode and see what it does...
java -Xint <usual arguments> YourProgram <its arguments>
Chuck