r - Frustration using rJava to call a third party Java jar

Question

I'm trying to use R to hook the Java code from the GSRad project. The GSRad Java code is available online and comes as a One-Jar project jar (I was not familiar with One-Jar until today). I can run the One-Jar file just dandy using the following command (after unzipping the file from the above link):

 java -jar gsrad_sample.jar

When I pop open the gsrad_sample.jar file I see a jar titled clima_GSRAD-1.0.0.jar in the /lib/ directory which contains the class files I want to hook with R. I've pulled out the jar of my affection and tried the following, to no avail:

library(rJava)
.jinit()
.jaddClassPath( "/home/jal/Documents/DSSAT/gsrad/clima_GSRAD-1.0.0.jar" )
.jnew( "cra/clima/gsrad/GSRBristowCampbellStrategy" )

Any tips on how I might hook the classes inside the clima_GSRAD-1.0.0.jar? I'm flummoxed.

EDIT

The GSRad site requires registration which is annoying. The full zip file which contains the Doxygen documentation for the Java package as well as the One-Jar jar file is available here and if you pop that open the jar that has the classes I want to hook is this one.

Answer 1

Let me preface my answer by saying that I'm no expert in Java / rJava, so apologies if this isn't 100% correct. I hope it's a step in the right direction though.

Start by unzipping gsrad_sample.jar to C:/gsrad (or adjust your paths based on where you unzip it). Then add all the contents of C:/gsrad/lib to your class path:

library(rJava)
.jinit()
.jaddClassPath(dir( "C:/gsrad/lib", full.names=TRUE ))
.jclassPath()
.jnew( "cra/clima/gsrad/GSRBristowCampbellStrategy" )