Returning python list to Java

Question

I have a Java application which calls some Python code. I have some problem in understanding how returning lists from Python to java.

Let's assume I have a very simple python module as follow:

def myFunc(param):
    print param
    return [ ["a","b"] , ["c","d"] , ["e","f"] ]

And a java piece of code that call this function:

String funcName = "myFunc";
try {
    PythonInterpreter interpreter = new PythonInterpreter();
    interpreter.exec("from myModule import * \n");
    PyObject someFunc = interpreter.get(funcName);
    someFunc.__call__(new PyString(workspacePath),new PyString(deployName));
}
catch(Exception e){
    e.printStackTrace();
    throw new Exception("Error while generating client resources.", e);
}

How can I transform the returned object to something that i can easily iterate over? How can I extract the string which are present in the list?

I tried messing around a bit with PyList or Iterable PyObject but with no success so far. Any idea?

Thanks

First you need to keep the returned PyList, PyList pl = someFunc.__call__(etc) — Hugh Bothwell
– Hugh Bothwell, Commented Jan 23, 2015 at 14:47
the problem is that the returnd type for the moment is PyNone that i cannot directly cast to PyList. someFunc.__call__(new PyString(deployPath)).asIterable() also does not return an Iterable object. — Stefano
– Stefano, Commented Jan 23, 2015 at 15:02

davidrmcharles · Accepted Answer · 2015-01-23 18:13:21Z

1

You can construct Java objects. If the intended consumer is a Java program, that may be the thing to do.

import java.util.ArrayList as ArrayList
import java.lang.String as String
...
javaList = ArrayList()
for subList in [ ["a","b"] , ["c","d"] , ["e","f"] ]:
    javaSubList = ArrayList()
    for s in subList:
        javaSubList.add(String(s))
    javaList.add(javaSubList)
return javaList

edited Jan 23, 2015 at 18:13

answered Jan 23, 2015 at 18:02

davidrmcharles

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