Just a heads up Java access to FGDB can be tricky because the FGDB library has ZERO support for threads. In fact the thread support is so bad that certain operations (involving XML) have to always be done in the same thread. If that thread no longer exists then the api will cause a crash if you try and do any operation involving XML (e.g. creating a new table, opening a FGDB etc).
Also make sure you implement careful synchronization to any static methods and access to methods on each FGDB that you open.
