Frustrations with ArcObjects

I've been working on the project mentioned last week, and found something interesting in ArcObjects for Java.  It comes out looking like a bug, but it is just bad code that is hard to detect (partly because it involves setting a value a programmer would never expect to set).

The problem manifests itself in an error like this:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x60e9f090, pid=6184, tid=3704
#
# JRE version: Java(TM) SE Runtime Environment (8.0_05-b13) (build 1.8.0_05-b13)
# Java VM: Java HotSpot(TM) Client VM (25.5-b02 mixed mode windows-x86 )
# Problematic frame:
# C  [GdbCoreLib.dll+0x14f090]
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
# C:\Users\arohne\workspace\GPS HHTS Analysis Esri Export\hs_err_pid6184.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

I poured over this for days, and even considered sending this to ESRI Support.  As I continued looking into it, I found the problem:

int fieldCount=0;
for(java.lang.reflect.Field f:GPSData.class.getDeclaredFields())
if(Modifier.isPublic(f.getModifiers()))
fieldCount++;

fieldCount+=2; //FIXME: Trying to @&#$ things up
fieldsEdit.setFieldCount(2+fieldCount);

Previously, I didn't have the loop and instead had fieldsEdit.setFieldCount(2+GPSData.class.getDeclaredFields()+2);.  The problem was that it was returning all the fields (both public and private), but I only defined public fields.  This caused that error.  I tested this by adding the fieldCount+=2; to the code (hence the FIXME tag) and was able to get things to work without intentionally changing the field count and break it when I have an incorrect field count.

I hope this helps someone out, as it isn't documented elsewhere that I could find.

-A-

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