Newbie Question about NoClassDefFoundError

I am new at this (first time using Java routines from RPGLE) but I have a problem that I have not been able to find in the archives.

I am attempting to demonstrate the feasibility of using Java routines to create XLS spreadsheets to replace many of the reports that we deliver to the users as CSV now. I got Scott Klement's "Excel Spreadsheets from RPG" article with the source code (Thanks Scott). I am trying to compile and run the XLCRTDEMO program. When I run it, it is attempting to define a formula when the Java Machine throws this error

Additional Message Information

Message ID . . . . . . : RNX0301 Severity . . . . . . . : 50
Message type . . . . . : Escape
Date sent . . . . . . : 10/06/08 Time sent . . . . . . : 08:59:46

Message . . . . : Java exception received when calling Java method.
Cause . . . . . : RPG procedure HSSF_FORMU in program MR0473/HSSFR4 received
Java exception "java.lang.NoClassDefFoundError: java/util/regex/Pattern"
when calling method "setCellFormula" with signature "(Ljava.lang.String;)V"
in class "org.apache.poi.hssf.usermodel.HSSFCell".
Recovery . . . : Contact the person responsible for program maintenance to
determine the cause of the problem.
Technical description . . . . . . . . : If the exception indicates that the
Java class was not found, ensure the class for the method is in the class
path. If the exception indicates that the Java method was not found, check
the method name and signature. If the signature is not correct, change the
RPG prototype for the method, or change the Java method, so that the return
type and parameter types match. You can determine the signatures for all the
methods in class XYZ using command QSH CMD('javap -s XYZ').


It looks to me like I am missing a JAR file but I don't know which one has the Pattern method. (Do I have that right?). Can anyone tell me if I understand the problem correctly and what I need to do to correct it?

Thanks,

Marvin