Comments on: Using JavaGD in Java applications

By: Zoe

Zoe — Thu, 20 Oct 2011 18:02:30 +0000

Thanks for the helpful post.
I am not very familar with R. I have just tried your example, it doesn’t work on my PC (Windows). I am wondering if it is because of the way to environment variable in Windows should be different than the code in your example as following:
engine.eval(“.setenv <- if (exists(\"Sys.setenv\")) Sys.setenv else Sys.putenv");
engine.eval(".setenv(\"JAVAGD_CLASS_NAME\"=\"JavaGDExample\")");

How could I set the environment variable in PC?

Thanks a lot,
Zoe

By: Kornelius Rohmeyer

Kornelius Rohmeyer — Thu, 08 Sep 2011 21:07:00 +0000

Hi Michael,
yes of course the extensibility is the goal! Of course you can just write a main method with the following lines and nothing else in the class:

Rengine engine = new Rengine(new String[] {"--vanilla"}, true, null);
engine.eval("library(JavaGD)");
engine.eval("JavaGD()");
engine.eval("plot(rnorm(100))");

But that’s not the point.

Best regards, Kornelius.

By: Michael Theobald

Michael Theobald — Thu, 08 Sep 2011 19:58:31 +0000

Eliminating the import statements for the java.awt and javax.swing classes as well as the doOpen() and doClose() methods and the WindowListener code makes no difference in the function of this class as published. Only the code in the main() method appears to be used. Therefore, in my opinion, the code example could either be made more complete or made shorter.

It does work!
Michael

By: Kornelius Rohmeyer

Kornelius Rohmeyer — Thu, 14 Jul 2011 10:41:50 +0000

Dear Michelle, please try to add the directory where the file JavaGDExample.class is found to the CLASSPATH. If you call java directly in the directory, it is simply the following in the bash on unix machines: export CLASSPATH=\$CLASSPATH:.

By: Michelle

Michelle — Wed, 13 Jul 2011 20:56:35 +0000

Hi there,

Thanks for the helpful post. When I run your example, I get this error:

Exception in thread “Thread-1″ java.lang.NoClassDefFoundError: JavaGDExample
at org.rosuda.JRI.Rengine.rniEval(Native Method)
at org.rosuda.JRI.Rengine.eval(Rengine.java:549)
at org.rosuda.JRI.Rengine.eval(Rengine.java:527)
at gov.pnl.mpv.views.JavaGDExample.main(JavaGDExample.java:42)
Caused by: java.lang.ClassNotFoundException: JavaGDExample
at java.net.URLClassLoader[latex cssclass="latex-inline"]1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher[/latex]AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
… 4 more

Do you have any suggestions?