One of the nicest things about JRuby (apart from performance and stability) is that you get easy access to all the wonderful Java libraries out there, which you can use with Ruby style syntax. These are often far higher quality than the Ruby equivalent, if that Ruby equivalent exists in the first place.
I've heard this argument a few times. As someone that's not new to Ruby but hasn't touched Java, can you elaborate as to what these awesome Java libraries are?
There's basically a library for everything. Creating or rendering PDFs? Several choices. Converting document formats? Choose the one with the license you like the most. Extracting data? Any format you want.
Then there's algorithms, support for just about any protocol under the sun. And the Java standard library is surprisingly complete as well - what you need might even be installed with your JVM.
Try googling for a Java library next time you think of something you want to do.
Our app sells to the finance vertical, so we deliver a lot of data in Excel. There is a really great project called Apache POI that does just what we need. Yes, there is also the Ruby spreadsheet gem, but while the gem itself works fine most of the time, the underlying reverse-engineering of the BIFF8 (Excel 97-2000) format is sketchy at best. Spreadsheets generated with the spreadsheet gem don't behave as expected in Excel. For example, if you click the '%' format button, you get an error message. This ends up making our product look unpolished.
This kind of turned in to a spreadsheet gem rant, but if you step back, it's typical of a greater problem. The Ruby community is relatively small when compared with the Java community. It's also significantly less "enterprisey". This means that you'll see a lot of effort put in to things that developers like -- clever libraries, syntactic "sugar", etc -- but you're less likely to see mature libraries like Apache POI. Who the hell wants to sit around and figure out BIFF8, anyway? A lot of the enterprise stuff just isn't fun, but there are plenty of Java devs who get paid to do it for their day jobs.
