My general advice when using Inline is to keep data passed between Perl and the other language as simple as possible. Passing a Perl object to a Java object as a method parameter is doable, but seems advisable. I tried to make sure I was only passing strings through to Java.

Clearly some Java classes expect more complex data structures to be passed to them - but you write wrappers for those, and do (for example) JSON encoding/decoding at each end.