has anybody found a library that works well with large spreadsheets?
I've tried apache's POI but it fails miserably working with large files - both reading and writing. It uses massive amounts of memory leaving you needing a supercomputer to parse or create a 20+mb spreadsheet.
Surely there is a more memory efficient way and someone has written it?!
Have you tried JExcelAPI as an alternative to POI ? I confess I can't comment on it's memory efficiency.
I cannot really recommend a library to you. But when you need the best performance, it might be worth a try to go to the people who came up with Excel in the first place. I guess the APIs that are available from .NET are much more efficient in handling Excel files. So the idea would be to implement a web service or similiar component in .NET that does most of the Excel-related grunt work for you and just invoke that from Java.
at time of posting, there is no pure java scalable solution for reading and writing large excel files.
This is basically the same idea as Jannik's, but you use the Java COM Bridge to access the Excel APIs directly from Java. We have had good success doing this with Word. Obvious downside is that it only works on Windows.
May be CSV file format can help you. You just need to seperate each value by comma and save file with .csv extension.
@pstanton.. I was working on a similar solution and was able to write large excel 2007 files with hundreds of rows exported from database. Here is the link to it: http://vikramvkamath.blogspot.com/2010/07/writing-large-excel-files-excel-2007.html
My solution is an extension on Yegor Koslov's SheetWriter class follow this http link: svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/BigGridDemo.java and it works very well for me. Let me know in case you face any issues.
~Vikram