I created a skeleton R package:
lib
jarFileHere.jar
R
r_code_file.R
The r_code_file.R tries to references a class file in j
Make your structure like:
inst
java
jarFileHere.jar
R
r_code_file.R
For examples on how to include java in your package look at the helloJavaWorld package.
Also take a look at the source of Deducer and DeducerplugInExample. There is a tutorial on including java code in your package available on Deducer's web manual: http://www.deducer.org/pmwiki/pmwiki.php?n=Main.Development#suaptijc