Trouble with running java using Popen

[Edward Grefenstette]

I have a java prog I need to run at some point during the execution of
a python module.

The path to the folder containing the all the relevant java stuff
(which runs fine from the command line) is stored in pkgpath. The
relevant code is this:

>>> os.chdir(pkgpath)
>>> arglist = "java -Xmx1024m SemanticVectorsEvaluator ." + indexpath
>>> SemVectPackage = Popen(arglist, stdout=PIPE, shell=True)
>>> SemVectPackage.wait()

Here indexpath is the path to a particular index file (usually
indexpath = "./indexfolder/fileindex"), so that effectively Popen
should be running the equivalent of the shell command:
-
java -Xmx1024m SemanticVectorsEvaluator ../indexfolder/fileindex
-
which, again, runs fine in the terminal.

However running the program returns the following error (echoed from
shell, doesn't interrupt prog):
-
Exception in thread "main" java.lang.NoClassDefFoundError:
SemanticVectorsEvaluator
-

I have no idea why this isn't working. Anyone have any suggestions as
to how I might troubleshoot this?

Best,
Edward