How to call java function from within Jython embedded?

Question

I have created an PythonInterpreter object, and want to call a java function but keep getting the error:

Exception in thread "main" Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'jytest2' is not defined
Java Result: 1

How do you call a java function from a live running system?

public static void main(String args[])
    {      
        ModRet modRet = new ModRet();
        jytest();
    }

public void jytest()
    {
        PythonInterpreter interp = new PythonInterpreter();

        interp.exec("print \'Hello; jython has successfully been embedded!\'");
        interp.exec("print " + FPS);
        interp.exec("jytest2()");

    }

    public void jytest2()
    {
        System.out.println("HIHIHI");
    }

It'd be really helpful if you could post some of the relevant Jython code — Eric Wendelin
– Eric Wendelin, Commented May 12, 2011 at 20:13
I did find one way to accomplish this: by running the constructor in jython. But is there another way? — orkel
– orkel, Commented May 12, 2011 at 20:17
The interp.exec(String) will only interpret in Python/Jython language; did you have the Python function jytest2() created for interpretation? That is what I can understand from the error message as it could not find the function...You may need to import from a library that has the function first before you can use it. — eee
– eee, Commented May 13, 2011 at 1:28

Eric Wendelin · Accepted Answer · 2011-05-12 21:18:30Z

1

I generally find that I need to use the Object Factory pattern and invoke things via an Interface as described in the Jython Book - Chapter 10

I'm still not super-clear on what you're trying to accomplish, so I don't have any code for you; but I'm sure you'll find the book helpful.

answered May 12, 2011 at 21:18

Eric Wendelin

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Comments

Ning Sun · Accepted Answer · 2011-05-13 02:21:27Z

By default, the current classpath is included in jython path. To access any method in the path, you should do an import.

package com.mycompany.jythontest;


import org.python.util.PythonInterpreter;


public class App 
{

  public static void sayHello(String hello) {
    System.out.println(hello);
  }

  public static void main( String[] args )
  {
      PythonInterpreter py = new PythonInterpreter();

      py.exec("from com.mycompany.jythontest import App");
      py.exec("App.sayHello('hello')");
  }
}

And if you want to access a java instance in jython, you can use py.set(string, object) to make it accessible in the context. (Just like javax.scripting)

      App app = new App();
      py.set("appinstance", app);
      py.exec("appinstance.sayHi('hello world')");

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