This is the development repository of Jython, the implementation of Python in Java. Only version 2.7 of Python can be supported at present (but watch this space for a 3.x version).

Jython provides good compatibility with Python 2.7 the language. Also, a high proportion of the standard library is included, taken from late versions of CPython (around 2.7.13). Some standard library modules have a Jython-specific implementation that has not kept pace with its CPython counterpart.

Jython 2.7 support for the Python ecosystem includes built-in support of pip/setuptools. You can use bin/pip if the targets do not include C extensions. There is a native launcher for Windows (bin/jython.exe) that works essentially like the python command.

Jim Baker presented a talk at PyCon 2015 about Jython 2.7, including demos of new features: https://www.youtube.com/watch?v=hLm3garVQFo

Python 2.7 (the language) is no longer supported by the PSF. Running on Jython should not be considered an alternative to porting your application to Python 3, due to the limitations cited here and the small amount of effort available to support 2.7.x. Jython 2.7 is offered for continuity because a 3.x is not yet available.

See ACKNOWLEDGMENTS for details about Jython's copyright, license, contributors, and mailing lists. Consult NEWS for detailed release notes, including bugs fixed, backward breaking changes, and new features. We sincerely thank all who contribute to Jython, by bug reports, patches, pull requests, documentation changes and e-mail discussions.

Binary downloads are available from https://www.jython.org/download along with Maven and Gradle dependency information.

The project uses Git for version-control, and the master repository is at https://github.com/jython/jython, You should clone this repository to create a buildable copy of the latest state of the Jython source. Start a new branch for any bug-fix or experimentation you plan.

The previously authoritative repository at https://hg.python.org/jython is not now in use, remaining frozen at v2.7.2.

Jython is normally built using ant. It is necessary to have Ant and at least a Java 8 SDK on the path. To build Jython in development, we generally use the command:

ant

This leaves an executable in dist/bin that you may run from the check-out root with:

dist/bin/jython

Other ant targets exist, notably clean, javatest and jar.

You can test your build of Jython (by running the regression tests), with the command:

dist/bin/jython -m test.regrtest -e -m regrtest_memo.txt

or by invoking the Ant target regrtest.

If you want to install a snapshot build of Jython, use the command:

ant installer

This will leave you with a snapshot installer JAR in dist, that you can run with:

java -jar jython-installer.jar

for the graphical installer, or:

java -jar jython-installer.jar --console

For the console version. (A --help option gives you the full story.)

We have a Gradle build that results in a family of JARs and a POM. This is intended to provide the Jython core in a form that Gradle and Maven users can consume as a dependency. Invoke this with:

PS> .\gradlew publish

and a JAR and POM are delivered to .build2\repo

Whereas the JARs delivered by the installer are somewhat "fat", embedding certain dependencies in shaded (renamed) form, the JAR from the Gradle build is "spare" and cites its dependencies externally through a POM.