Re: How to mimic a subfile with java? -- JAVA400-L

The guys at Linoma Software have put something like what you describe in
their product, Surveyor/400.  I use their product to edit multiple records
in a "sub-file" style, it works pretty much as you've described.  There are
buttons to jump to the beginning or end of the file as well as buttons to
scroll by page.  I couldn't tell you how they do it but I know that some of
their developers subscribe to the midrange-L lists, so maybe someone is
listening.

Jack Mullins
Sun Ergoline, Inc.
www.sunergoline.com





Hundreds of thousands of records?  Yes, that would take a long time to load,
no matter where you did it.  But remember that an AS/400 subfile is limited
to 9,999 records.  (At least it was the last time I checked, that limit
could have been changed.)  That's a practical limit anyway, people are not
going to scroll through over 10,000 records, or if they do, they will
probably be cursing you for not giving them a search option.

The way people got around the huge-startup-time problem in RPG was to load
the subfile a page at a time.  You've probably seen that technique; just
display the first page, and load additional pages each time the user presses
page-down.  You could likely do the same thing in Java, but not with a JList
out of the box.  Normally a JList is wrapped in a scroller that claims to
show the current cursor position in the list; you wouldn't want a scroll
bar, since you don't actually know how big the list is if you only load part
of it.  Instead you'd want to wrap it with some other component that
provides, for example, a Next-Page and a Prev-Page button, and uses those
buttons to load the visible list with the appropriate page of data.

Hope these random thoughts help.

PC2

-----Original Message-----
From: Robert Upshall [mailto:rupshall@psasoft.com]
Sent: October 2, 2001 12:05
To: java400-l@midrange.com
Subject: How to mimic a subfile with java?


I am attempting to write a java application that would display a customer
list loaded from a db2 file.  When the uses selects a customer it will then
bring them to a customer detail screen.

My question is, what is the best way to load this list.  The method I used
was just a dow not eof loop that appended items to a JList.  This worked
fine for my testing, with minimum records, but when you start to get into
thousands and even hundreds of thousands of records it takes quite a long
time to load.

I don't expect to be able to get subfile load speeds(can I?) but there must
be methods to allow the speeding up of this process.  Has anybody ever done
anything like this?

Any help would be greatly appreciated

Robert Upshall
Professional Software of Amarillo
(806) 358-8928
rupshall@psasoft.com