Introducing jbang-fmt

I really did not want to do this, but after I and others tried to convince google-java-format one too many times to not mess with JBang directives like //DEPS or the ///usr/bin/env lines, I finally gave up and made my own.

While I’m a fan of tools like Spotless, their command-line usage is still too cumbersome. This prompted me to create an improved solution called jbang-fmt, in the hope that its key features will be adopted by competing programs and ultimately render itself obsolete

So here it is: https://github.com/jbangdev/jbang-fmt

I would have called it java-fmt as it is not tied to JBang - you can use it as-is with any Java code; but I don’t like visits from lawyers.

Why jbang-fmt?

• Simple: One command to format any Java file or directory

• Fast: Built for command-line usage and using virtual threads

• Flexible: All the options you need (but probably shouldn’t use)

• JBang-aware: Respects //DEPS and ///usr/bin/env directives

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.

Installation

jbang app install jbang-fmt@jbangdev

One more thing…​

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.

--check

This is a really simple flag that will check if the code is formatted without making any changes.

jbang-fmt --check .

If the code is not formatted it will exit with a non-zero code. Useful in CI pipelines to fail the build if the code is not formatted and as git pre-commit hooks - see Git Integration for an example of the latter.

Maven and Gradle integration

You can use it from Maven and Gradle using their jbang support - no additional plugins needed. See Maven and Gradle in documentation for more details.

Shortcuts for common "debates"

• Tabs vs spaces? Use --indent-with=tab or --indent-with=space

• Big vs small monitor? Use --line-length=120 or --line-length=40

• Java version nostalgia? Use --java-version=4 for the good old days or --java-version=25 for living on the edge

• Compact docs? Use --indent-size=2 etc.

…​and if you want full control you can use -Skey=val to override any Eclipse formatter property.

But again, remember I told you to just use one format - above is not meant to be used unless you are ready for war.

In addition it also supports using @-files in case you ignored my advice and want to go crazy on shared formatting.

Conclusion

So - what are you waiting for? Install it and start formatting your code today!

And if you have any feedback, suggestions, or want to contribute, please open an issue on GitHub!

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1. I wanted to offer both Google Java Format and Eclipse but Google Java Format even on API level seems to have no consistent ability to ignore lines.