On Tue, 9 Oct 2018 at 21:12, <JRusling@xxxxxxxxxxx> wrote:

I don't know how the interface to Java works. I don't know if you can
just change the declarations on the RPG end without screwing up the
parameter passing.
John Y.

Thanks John. I don't either :-(

I'm an RPG II geezer. If I can get going with it, that's a good sign
for the rest of the group.
My 'Aha!' moment came when I stopped trying to use these Java wrappers
'by rote'.
Spoiler: they aren't a black box. They are wrappers for Java functions
written by a Java open source team.
I wasn't running RPG code that I could dissect and decipher - I was
running Java code that was... well, not so easy for me.
So I dropped back to basics and started reading the documentation. In
the Java world, that's called Javadoc. You can find the HSSF Javadoc
at the HSSF project home page:
http://poi.apache.org/components/spreadsheet/index.html Click the
Javadoc link in the nav menu at the left.

Dropping back to Java has benefits that I greatly enjoyed.
1) Examples of how to use the HSSF classes and methods are plentiful - in Java.
2) Tutorials of how to use them are available - in Java.
3) I was able to understand the Javadoc and match up Scott's RPG work
to the Javadoc, which is foundational for understanding how the
interface works, and for writing my own wrappers for things Scott
hadn't got to.

This leads to my advice. Find a Java example of what business
thing/function you want to accomplish. Copy/paste that (do it by rote,
without understanding). You'll work out CLASSPATH issues, you'll work
out Javadoc issues, if you run into problems there are literally
millions of Java programmers on Stack Overflow who can help you. In
short, you'll start out as a beginner, and progress naturally toward
understanding. That time spent in the Java world is not wasted because
you aren't running RPG code. You are running Java code.

When I started, I was learning two things at the same time - RPG to
Java mapping, and the Java implementation of HSSF. It turns out that
for me, anyway, learning one at a time was easier.

I never documented HSSFR4 in the midrange wiki because I feel weird
doing it. I'm not speaking authoritatively, but it seems to me that
HSSFR4 is a chimera; part open source, part of Giovanni's CGIDEV2,
part of a copyrighted magazine series... I just feel odd putting
information in the wiki. But perhaps I'm overthinking it (who, me?).
After all, we routinely swap information on the mailing list... I'll
try to get a page started. It's my experience that people are
reluctant to work with a blank page, and having something to edit /
add to is easier.


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