Run Jython Standalone Jar On Windows

This tutorial will show you how you can run jython-standalone.2.7.2.jar on a Windows machine. Using Jython standalone, you will be able to execute Python scripts, or use Python REPL.

Pip install for Jython is not covered.


  • Basic knowlege of Windows PowerShell

Guide outline

  1. Install OpenJDK 17
    1. Download Java
    2. Add Path Java variable
    3. Verify Java Installation
  2. Download Jython.jar and Guide Stub
  3. Run Jython Standalone
    1. Verify Jython Installation
    2. Run Jython REPL
    3. Run Jython Script
  4. Summary

Install OpenJDK 17

Download Java

  1. Download Windows 10 x64 JDK jdk-screen
  2. From zip extract, jdk-17 folder to disk C:\.

Absolute path to the JDK installation should be C:\jdk-17

Add Path Java variable

This part assumes you have installed OpenJDK in C:\jdk-17 folder.

  1. In Windows search type "Edit environment variables for your account"
  2. Double click [Path]
  3. Click [New]
  4. Enter this: C:\jdk-17\bin; press Enter key
  5. Click [OK] env variable menu

Verify Java Installation

In PowerShell run:

java -version

Assert Java version is correct:

openjdk version "17.0.1" 2021-10-19
OpenJDK Runtime Environment (build 17.0.1+12-39)
OpenJDK 64-Bit Server VM (build 17.0.1+12-39, mixed mode, sharing)

If you see OpenJDK 64-Bit Server VM your installation was successful.

Download Jython.jar and Guide Stub

This tutorial includes a zip file containing folder structure and a test script.

  1. Download the stub and extract it on your PC.
  2. Download jython-standalone.2.7.2.jar, and save it to jythonstub/lib folder.

Run Jython Standalone

PowerShell commands below are executed in folder jythonstub/

Verify Jython Installation

Assert that Jython runs inside JRE:

java -jar ./lib/jython-standalone-2.7.2.jar --help

expected result:

usage: jython [option] ... [-c cmd | -m mod | file | -] [arg] ...
Options and arguments:
-B       : don't write bytecode files on import
-c cmd   : program passed in as string (terminates option list)

Run Jython REPL

Assert that Jython REPL is working:

java -jar ./lib/jython-standalone-2.7.2.jar

Expected result:

Jython 2.7.2 (v2.7.2:925a3cc3b49d, Mar 21 2020, 10:03:58)
[OpenJDK 64-Bit Server VM (Oracle Corporation)] on java17.0.1
Type "help", "copyright", "credits" or "license" for more information.

Run Jython Script

Assert that Jython script is working, th:

java -classpath ./lib/* org.python.util.jython ./

It should print:

PYTHON: Hello World!
JAVA: Hello World!

Command explanation:

  • java: Is OpenJDK, we installed.
  • -classpath ./lib/*: tells your java runtime to scan all .jar files inside the lib/ folder, i.e. makes them available for import inside Jython.
  • org.python.util.jython : reverse URL notation to jython class containing a main() method(notice the class name is jython, not Jython)
  • ./ Name of the Jython script executed.


If you managed to run a Jython script using this guide, good news. Now you have a clean environment to work on your Jython projects. Do not forget to place additional jar files to the lib/ folder!