sbt-java-formatter

An sbt plugin for formatting Java code. This plugin began as a combination of ideas from this blog post and this maven plugin, though it has evolved since.

Usage

Add the plugin to project/plugins.sbt:

// Default plugin:
addSbtPlugin("com.github.sbt" % "sbt-java-formatter" % --latest version---)

// Alternative for Java 17+: wraps formatter commands in a fresh sbt JVM,
// so you do not need to configure `--add-opens` manually, see below.
addSbtPlugin("com.github.sbt" % "sbt-java-formatter-add-opens" % --latest version---)

For available versions see releases.

The following commands are available:

• javafmt formats Java files
• javafmtAll formats Java files for all configurations (Compile and Test by default)
• javafmtCheck fails if files need reformatting
• javafmtCheckAll fails if files need reformatting in any configuration (Compile and Test by default)

The sbt-java-formatter-add-opens plugin wraps the above commands and, on Java 17+, runs them in a fresh sbt JVM with the required jdk.compiler module access flags. From a user perspective, the commands stay the same and no manual JVM flags need to be configured.

• The javafmtOnCompile setting controls whether the formatter kicks in on compile (false by default).
• The javafmtStyle setting defines the formatting style: Google Java Style (by default) or AOSP style.

This plugin requires sbt 1.3.0+.

Java 17+

google-java-format relies on internal jdk.compiler APIs. On Java 17 and newer, access to those APIs is strongly encapsulated by the module system.

If you depend on sbt-java-formatter-add-opens, the formatter commands (javafmt, javafmtAll, javafmtCheck, javafmtCheckAll) automatically relaunch in a JVM with the required module flags, instead of requiring manual -J--add-opens=... setup.

Enable in other scopes (eg IntegrationTest)

The sbt plugin is enabled by default for the Test and Compile configurations. Use JavaFormatterPlugin.toBeScopedSettings to enable the plugin for the IntegrationTest scope and then use It/javafmt to format.

inConfig(IntegrationTest)(JavaFormatterPlugin.toBeScopedSettings)

Configuration

This plugin uses the Google Java Format library, which makes it quite opinionated and not particularly configurable.

If you want to tweak the format, take a minute to consider whether it is really worth it, and have a look at the motivations in the Google Java Style Guide. If you decide you really need more flexibility, you could consider other plugins such as the sbt-checkstyle-plugin

Contributing

Yes, we'll happily accept PRs to improve the plugin.

Take a look at the contributors graph if you want to contact any of the contributors directly.

License

Apache v2