Jython cant get eval output as String

Question

Im having an issue using Jython, I wish to capture the output of the eval function:

Object Pyoutput = pyEngine.eval("print('Hello World')");
System.out.println(Pyoutput.toString());

This was how i thought it could be done, but instead turns into a reference to the object. After some googling i found ways only to access specific variables etc that have been previously evaluated.

I have also tried exec:

interp.exec("print("hello world")");

But this cannot be assigned to a variable as its type is void. So my question is, is it possible to recover the entire output of eval or exec into a Java string so it can be displayed in another text field?

Answer 1

Pyoutput in the question is null (print does not return anything), so Pyoutput.toString() results in a NullPointerException.

It works with an expression that yields a value. The following program prints 6.

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class Main {
  public static void main(String[] args) throws ScriptException {
    ScriptEngine pyEngine = new ScriptEngineManager().getEngineByName("python");
    Object Pyoutput = pyEngine.eval("2*3");
    System.out.println(Pyoutput.toString());
  }
}