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Calling python module from Java

I want to call a function from a python module from Java using "PythonInterpreter" and here's my Java code

PythonInterpreter interpreter = new PythonInterpreter();

interpreter.exec("import sys\nsys.path.append('C:\\Python27\\Lib\\site-packages')\nimport helloworld");

PyObject someFunc = interpreter.get("helloworld.getName");

PyObject result = someFunc.__call__();

String realResult = (String) result.__tojava__(String.class);

System.out.println(realResult);

and the Python code (helloworld.py) is below:

    from faker import Factory
    fake = Factory.create()

    def getName():
       name = fake.name()
       return name

The problem I'm facing is while I'm calling interpreter.get when it returns a null PyObject.

Any idea what's going wrong? The python code runs fine from IDLE

EDIT

I just did a bit of change in the code as below

PythonInterpreter interpreter = new PythonInterpreter();

interpreter.exec("import sys\nsys.path.append('C:\\Python27\\Lib\\site-packages')\nimport helloworld");


PyInstance wrapper = (PyInstance)interpreter.eval("helloworld" + "(" + ")");  

PyObject result = wrapper.invoke("getName()");

String realResult = (String) result.__tojava__(String.class);

System.out.println(realResult);

and I introduced a class in my python module

from faker import Factory

class helloworld:

def init(self):
    fake = Factory.create()

def getName():
    name = fake.name()
    return name

Now am getting the error below

Exception in thread "main" Traceback (innermost last):
  File "<string>", line 1, in ?
TypeError: call of non-function (java package 'helloworld')

Answer*

1. You cannot use python attribute access in [`PythonInterpreter.get`](http://www.jython.org/javadoc/org/python/util/PythonInterpreter.html#get(java.lang.String)). Just use attribute name to get the module, and retrieve attribute from it.
 2. (EDIT PART) Python code is totally broken. Please see the proper example below. And, of course, [www.python.org](http://www.python.org).
 3. (EDIT PART) First parameter of [`PyInstance.invoke`](http://www.jython.org/javadoc/org/python/core/PyInstance.html#invoke(java.lang.String)) should be method name.
 4. Below you can find working code sample for both cases

Main.java

    import org.python.core.*;
    import org.python.util.PythonInterpreter;

    public class Main {

        public static void main(String[] args) {
            test1();
            test2();
        }

        private static void test1() {
            PythonInterpreter interpreter = new PythonInterpreter();
            interpreter.exec("import hello_world1");
            PyObject func = interpreter.get("hello_world1").__getattr__("get_name");
            System.out.println(func.__call__().__tojava__(String.class));
        }

        private static void test2() {
            PythonInterpreter interpreter = new PythonInterpreter();
            interpreter.exec("from hello_world2 import HelloWorld");
            PyInstance obj = (PyInstance)interpreter.eval("HelloWorld()");
            System.out.println(obj.invoke("get_name").__tojava__(String.class));
        }
    }

hello_world1.py

	def get_name():
	    return "world"


hello_world2.py

	class HelloWorld:
	    def __init__(self):
	        self.world = "world"

	    def get_name(self):
	        return self.world

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Edit Summary*

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in your solution how could you pass arguments to get_name(self, something)?

Paulo Oliveira
– Paulo Oliveira

2021-11-15 17:10:57 +00:00
Commented Nov 15, 2021 at 17:10

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