The short answer: You can't.
The long answer: You can, but it's a pain, and I would suggest trying to write reports in
Jasper Reports or some other Java-based reporting tool.
If you (or your boss) insist on Crystal, you will need to write C functions accessing Crystal's C API and then wrapping that in a JNI shell. This is not an easy task. Oh, and the CRPE API is no longer supported -- use the newer API -- although the newer API may not work for desktop-based applications.
Crystal does have a Java API, but that's only if you use their Crystal Reports Server in a distributed environment. You can't use it with Java in Swing apps.
IN short, Crystal seems to be pusing its reports as web-based reports instead of desktop-based reports. Support for the desktop-reporting is dwindling at Crystal. Unless your reports are already written, I urrge you to look at other reporting solutions. And even if they are already written, it may be easier to re-write them rather than trying to integrate Crystal. (I had Crystal integraed, but then it broke for some reason
Instead of fixing it, I switched to Jasper reports....)