I know the last implemented version of Java for Mac OS 9 is Java 1.1.8. Is there any way to use Swing with it? What should I be aware of? Are there any caveats/compatibility issues?
It is my understanding that on Windows at least, JRE 1.1.8 does not come with Swing, and in order to use Swing for JRE 1.1.8 you need to download a separate .jar file with the appropriate classes in it.
So, I speculate that on a Mac, JRE 1.1.8 also does not support Swing. I further guess that Apple did not write the Swing classes and place them in a separate .jar file to run with JRE 1.1.8.
Given the above, to run Swing, you probably need to be in Mac OS X. Also, it is my general understanding that Mac JRE 1.1.8 is not very stable, so that would be another motivation to update to Mac OS X and use JRE 1.4.
Swing does run on MacOS, at least the later versions of OS9 and maybe OS8. You will want to hunt down the last release of MRJ and the last release of JFC for MacOS. I looked on VersionTracker, and it looks like both of these are still available.
Of course, many applications now require later versions of Swing and/or Java, and there are certainly potential stability and performance issues.