I've let loose a new version of JKstat, also available from the jkstat project page.
This is version 0.19, and represents real progress. I'll start with some of the fiddly stuff: I've got rid of all the individual utility scripts (they were breeding out of control) and replaced them with a single jkstat script that takes subcommands. I've removed the native methods for looking up individual statistics, as there was no possibility of error checking (like to see if the value returned was valid). There's an client for nfsstat and the start of one to emulate the kstat(1M) perl client. I've got a swing widget that allows you to add a menu to any java client from which you can launch some of the demos.
The big feature is that I can now detect changes in the underlying kstat chain. I've added another class to handle this, so it's responsible for working out whether something has changed, and which kstats have been added and removed. This wasn't quite as big a job as I had feared.
Getting the demos to use this was somewhat more difficult. In particular, the browser took far more work than I ever expected. The kstats are in a tree, they're presented using a JTree, so you just update the tree, right. Wrong! I had originally placed the kstats into a Hashtable (it's a natural things to do), passed that to the JTree. Then Tom Erickson helped me out by creating a sorted Map, and a revised JTree that could take a Map. (And why some of the java swing components haven't moved into the 21st century and become aware of the Collections framework is beyond me.) I wasted a lot of time thinking I could update the Map and get the tree to refresh its view of the world, but it just didn't work. In the end I had to get rid of that and construct my own model, doing everything manually. Ugh.
It's not finished. Not all the demos handle updates. (Those using tables do - that was easy.) And the browser has a couple of cosmetic flaws: the newly added kstats aren't currently sorted correctly, and if you're watching a kstat that gets removed it doesn't tell you that anything has happened. But it's a major step forward and I'm going to take a deep breath and use this for a while before diving back in.