Looking at your code; your python code defines a class and a member method:

class JythonHello:
  def __init__(self, name): ...
  def sayHello(self): ...

And it seems that you intend to call that method:

 PyObject callFunction = interpreter.get("sayHello");
 PyObject result = callFunction.__call__(new PyString("Boban"));

But please note: sayHello() doesn't take any arguments. That self parameter is an indication that you have to call it on an object; but without any other parameters!

So, in pure python you would say:

helloVar = JythonHello("Boban")
helloVar.sayHello()

But your java code tries to call it like

sayHello("Boban")

So, the real answer is: step back; and re-think what you really intend to do; and then write code that works that way.

I would start by not adding the "class" part on the python side; instead try to simply invoke a function that takes a string argument for example!

And finally: could it be that you are on the wrong path altogether? The main point of jython is to write simply python code to do "debug" work within a running JVM. You are writing complicated Java code to use a bit of python code on the other hand ...