Click this link → Run Java in your browser - wait a moment and you have a running Java environment, showing Hibernate example in your browser. No JDK or IDE to install, no account, just works.

Or scroll down and click "Activate" below to run Java code right here in this blog post:

That is real Java. With real Maven dependencies. Output rendered in your browser with no additional install.

For those curious - above is using Jeamlit to render the chart in your browser. It should look something like this:

Jeamlit is a new library similar to Streamlit for Python, not done by us but inspired by JBang that allows building interactive web apps in Java with zero friction - do check it out!

I’ve been wanting to use //DEPS in Jupyter Notebooks for a long time, but it has been a pain to set up, so I talked with maintainers of JJava and Rapaio kernels and explored options. Each has their own way of dealing with dependencies - and I prefer to minimize the friction thus I created a JJava derived kernel that supports //DEPS directives in notebooks.

And in doing so I discovered that we could use Python’s existing infrastructure (Jupyter Notebooks, MyBinder and Thebe) to go some steps further.

There is a shockingly small amount of code to make this all work - and its in its infancy still; there is a lot more one can do with this - and I’m hoping you all will help make it better to make Java something you can share and use with zero friction.

Here’s what we’ve built:

Put it all together and you have a way to run Java code in your browser with no additional install.

Note: This is not just for browser-based notebooks - it also works in IntelliJ, VSCode, Cursor and other IDEs that support Jupyter Notebooks.

The fastest way is our new jbang.dev/try page.

In your browser (no install):

Locally (with Jupyter):

Works in IntelliJ, VSCode, Cursor, and any IDE with Jupyter support! If not - let us know!

Instant workshops — A browser tab replaces a 45-minute install session.

Runnable documentation — Stop making readers imagine the output. Let them press Run.

Shareable bug reproductions — "Can you reproduce this?" becomes a link, not a setup guide.

API exploration — Test a library with //DEPS, not pom.xml.

This is not about data science or competing with Python.

This is about making Java something you can share with zero friction — all in line with JBang’s mission.

Ready to experience zero-friction Java?

Get started:

This is still new and evolving - we have more ideas and plans for this, so stay tuned!

This is about making Java something you can share with zero friction — all in line with JBang’s mission.

Enjoy!

It is a simple tool that formats Java code using Eclipse Formatter!^[1] but by default does not mess with JBang directives like //DEPS or the ///usr/bin/env lines.

In its simplest form you just do:

jbang-fmt .

And it will format all the Java files recursively in the current directory.

If you want to format specific set of files and directories you can do:

jbang-fmt myscript.java src/main

That’s it - you don’t need to read more, just install it and use it.

jbang app install jbang-fmt@jbangdev

Since I made this in like 30 minutes as I was being nerd sniped I couldn’t resist adding a few more bell and whistles.

Before I show them - please know - that I really highly recommend you use one format in your project and in many ways I fully agree with google-java-format faq on locking down the formatting rules.

That said - the world is a messy place and we all have different needs - so I like to make formatting easy to do and enable easy experimentation - so I added all the ways I can think of a simple formatting tool could be useful.

You can run it directly using jbang mf@jbangdev or install it using jbang install mf@jbangdev to get it as a standalone tool.

You’ll notice keys like Import-Package and Export-Package are very long and hard to read. mf allows enabling structured output (-s or --structured) that supports certain well-known keys and when enabled will print the values as lists or maps.

Still long, but much easier to read.

mf supports filtering the manifest keys using a regex.

In its simplest form it lets you substring on keys

but you can also use a regex to filter the keys.

Finally, mf supports JSON(--json) and YAML(--yaml) output.

and they can be combined with the other options:

The decision to include JBang in a foundation stems from a desire to ensure its long-term sustainability and growth. Being part of a foundation, especially CommonHaus, provides JBang with a stable, independent home that supports its development and promotes collaboration. This move also opens up new opportunities for funding and contributions, further securing the project’s future and fostering an environment where JBang can thrive alongside other like minded open-source projects.

The guiding principles of CommonHaus summarizes it well:

These are important things for JBang - having a place to be hosted for ensuring continuity while still allowing individuality.

JBang will stay JBang. If you as a user notice it has moved, I will be surprised.

Maybe the about text of the CLI will change; that is about it.

The exact onboarding implication is still being defined, but it is expected to have minimal impact as we do most of the recommended things anyways.

Try out JBang if you haven’t already. If you see something that could need improvement or have a question, join the development on GitHub, open issues and discussions, and let’s help make Java truly available to anyone.

Have fun!

We made a jbang-catalog template available that setups of a jbang-catalog with automatic renovate bot based updates.

All repos in JBangHub uses this to ensure any Maven referenced artifacts will get updates, but anyone can use this in their own jbang-catalog outside JBangHub too.

Just start it using jbang init -t jbang-catalog <reponame> and add aliases to your jbang-catalog.

The latest release (0.116) of JBang adds jbanghub as a default jbang catalog so when you do jbang catalog list you get something like:

This list is not intended to be every jbang-catalog on the planet - but more a teaser on what is available out there. We encourage and accept edits/updates to that list at https://github.com/jbanghub/jbang-catalog.

Think something is missing - come contribute your favourite tool at JBangHub.

Have fun!

In your requirements.txt add:

jbang-python

or install it using pip install jbang

Then in your python code you can do:

With a hello.java that contains:

When you run this it will automatically install JBang and Java if necessary and then run the requested alias and java code.

Besides using it in your python code locally you can also use it from Jupyter Notebooks.

The jbang-python package is available on pypi and the source code is available on https://github.com/jbangdev/jbang-python.

Have fun!

Given you have a script name test.js:

And in package.json:

With a hello.java that contains:

When you run this using npm run test it will automatically install JBang and Java if necessary and you get an output like:

In this case JBang was already installed but it did go transparently and downloaded Java 18 as one of the scripts was called with --java 18.

The opportunities are endless!

jbang-npm was contributed by Peter Thomas and Pallafor Yodis from Karate hall of fame.

Very much appreciated and looking forward to see what you make happen with Java Script in your JavaScript!

Have fun!

Then in top we are going to add a few dependencies:

The first line is the magic "shebang" line that bash and other shells will interpret but for java it is just a comment. This is what allows you to run the script directly using ./grab-avatar

The dependencies used are as follows:

When you run ./grabavatars.java or jbang grabavatars.java these starting lines with //DEPS in them will be parsed and JBang fetches the dependencies to use during compilation and execution of your script.

The next is the class declaration which is mainly just annotations to define the main picocli command.

Then the meat of the code is to run git log --pretty=format:%ae|%an" which will return a line for every commit with email and author, like:

To do this I use zt-exec which has this great "one-liner" to run the process and for every line output let me process it.

And finally for every identified email and author - generates MD5 and download the url.

Now to run this when I have it locally is just: ./grab-avatars in root of a git repository.

But you can also run this directly from a url using:

jbang https://github.com/jbangdev/jbang/blob/HEAD/examples/grab-avatars

And then you can go full out and render with gource - notice the --user-image-dir .git/avatar:

Then you get a video which with a little bit of magic of video editing that looks something like this:

{#youtube "da0CuVbvWLg" /}

And that is about it - showed how to get started with jbang to port an existing perl script to java using a few dependencies.

See you next time!