Question

I want to use some Jython code as a Groovy closure so I believe I need to import the Jython file into the Groovy script and pass it into Groovy’s MethodClosure() function to generate the closure.

For example, I put this into a Groovy file:

import rand$py 

cl = MethodClosure(rand$py.Rand(), "nextDouble")

Evidently jythonc is deprecated and I couldn’t find it on my system so I generated the rand$py.class by importing it from another .py file and running Jython on the other file. The rand$py.class is located in the same directory as the Groovy file.

Here’s the error I’m getting when I try to execute the Groovy file:

Exception in thread "main" java.lang.NoClassDefFoundError: org/python/core/PyRunnable
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)

        ........

    at com.tinkerpop.gremlin.jsr223.ScriptExecutor.evaluate(ScriptExecutor.java:34)
    at com.tinkerpop.gremlin.jsr223.ScriptExecutor.main(ScriptExecutor.java:20)
Caused by: java.lang.ClassNotFoundException: org.python.core.PyRunnable
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)

It looks like it’s finding it because somehow it knows it’s a Python file (or does it know that because $py is in them name?). I don’t normally work in the JVM so I’m probably missing something fundamental.

EDIT: I changed import rand$py to import bogus$py to see if it generated the same error, and it did not so it looks like some part of it is finding the class file:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Script1.groovy: 80: unable to resolve class bogus$py
 @ line 80, column 1.
   import bogus$py
   ^

1 error

Answer 1

I would guess that the Jython libraries are not on your classpath. Look at the classpath section on Groovy Running