A modern, lambda-friendly, 120-character Java formatter — built in the open.
Documentation: openjavaformat.dev
open-java-format is released and developed independently. It began as a community fork of palantir-java-format, which is itself a fork of google-java-format, and every artifact is now built and published from this repository.
| Where | What |
|---|---|
| Maven Central | dev.openjavaformat:open-java-format, with -spi, -native and -jdk-bootstrap, and the Maven plugin dev.openjavaformat:fmt-maven-plugin from its own repository |
| Gradle Plugin Portal | dev.openjavaformat.java-format |
| JetBrains Marketplace | the IntelliJ IDEA plugin |
| GitHub Releases | native binaries, a runnable jar, the Gradle, IntelliJ and Eclipse plugins, every file signed |
Why the project exists is in the manifesto.
Each page is short and every command on it was run against the published artifacts.
- Gradle plugin
- Maven plugin
- Command line: a native binary, or a runnable jar
- IntelliJ IDEA
- Eclipse
- GitHub Action and pre-commit hook
Lines are up to 120 characters wide. A lambda stays on the line where it starts, and a long call chain breaks into one call per line.
google-java-format:
private static void configureResolvedVersionsWithVersionMapping(Project project) {
project.getPluginManager()
.withPlugin(
"maven-publish",
plugin -> {
project.getExtensions()
.getByType(PublishingExtension.class)
.getPublications()
.withType(MavenPublication.class)
.configureEach(
publication ->
publication.versionMapping(
mapping -> {
mapping.allVariants(
VariantVersionMappingStrategy
::fromResolutionResult);
}));
});
}open-java-format:
private static void configureResolvedVersionsWithVersionMapping(Project project) {
project.getPluginManager().withPlugin("maven-publish", plugin -> {
project.getExtensions()
.getByType(PublishingExtension.class)
.getPublications()
.withType(MavenPublication.class)
.configureEach(publication -> publication.versionMapping(mapping -> {
mapping.allVariants(VariantVersionMappingStrategy::fromResolutionResult);
}));
});
}- Same output, except for bug fixes. The formatter is the code of palantir-java-format 2.98.0, renamed and rebuilt in the open. Its output is the same except where it fixes a bug, and Migrate lists those fixes. Any later change to the output comes with a new minor version, see Versions.
- Identical Java packages.
com.palantir.javaformat.*stays, so your code and the SPI keep working. - One-line migration. Change the coordinates below. Nothing else.
A version is three numbers, <java>.<minor>.<build>, and each one answers a question of its own.
- The first is the Java version the formatter is built for, 21 today. It moves when the minimum Java version moves.
- The second moves with every change to the output: a fix in wrapping or alignment, a new rule, a new feature. A newer minor version can reformat code that the previous one left alone.
- The third moves with fixes that leave the output alone: a crash, a regression, an internal bug, a dependency update. A newer build formats every file exactly as the previous one did.
The line between the last two numbers is the output, not the kind of change: a fix that changes the output raises the second number, a fix that does not raises the third.
Up to 2.98.0.6 the version was palantir-java-format's with a build number appended. Once the bug fixes made the output differ from upstream, that numbering lost its meaning.
mise pins the tooling: mise.toml installs Temurin 21 and
act.
mise trust && mise install
./gradlew test # what the CI build job runs-PjavaRuntime=25 runs the same tests on JDK 25, as CI's jdk jobs do for 25, 26 and 27, and for
the early-access builds of 28, where value classes are a preview feature and the value modifier
tests run. The code is compiled for Java 21 either way. Gradle has to find that JDK: installed with
mise, or named with -Porg.gradle.java.installations.paths=/path/to/jdk.
The Gradle plugins' tests build their projects with Gradle 9.3.1, the oldest the plugins support.
-PtestkitGradleVersion=9.8.0 builds them with another, as CI's JDK 27 leg does: 9.3.1 does not run
on Java 27, and 9.8.0 is the oldest release that does.
Nothing inside the build downloads a JDK. gradle.properties turns toolchain auto-download off and
reads the installations from JDK21_HOME and GRAALVM_HOME, so a missing JDK is an error you can
read rather than a silent download.
The native image needs a GraalVM 25 behind GRAALVM_HOME. CI installs it with
graalvm/setup-graalvm and builds the image in a job of its own:
./gradlew -PnativeImage=true :open-java-format-native:nativeCompileGraalVM has to come from outside Gradle: unpacking a JDK that Gradle downloaded itself does not
preserve the symlink GraalVM ships at bin/native-image, and nativeCompile then fails on an empty,
unexecutable file.
The workflows run under act in Docker, so a change to .github/workflows can be checked before it
is pushed:
mise run ci:list # what jobs exist
mise run ci:lint # dry-run every job: resolves images, actions and steps, executes nothing
mise run ci:build # actually run the linux jar+native build job
mise run ci:native # actually run the linux-aarch64 native jobTwo caveats:
- act cannot containerise macOS, so the
macos-aarch64leg has to be checked by building the native image on a Mac. - On an Apple Silicon host the
ubuntu-24.04container runs as arm64, so the job labelledlinux-x86-64produces an aarch64 binary locally. Fine for exercising the workflow, not a substitute for real CI.
This project is a fork of palantir-java-format, which is itself a fork of google-java-format. It is distributed under the same Apache 2.0 License, and it keeps every upstream copyright notice — from both projects — permanently.
Neither Palantir Technologies Inc. nor Google LLC endorses, sponsors or is affiliated with this fork. "Palantir" and "Google" are trademarks of their respective owners, and Apache 2.0 §6 grants no rights to them; the rename described in this README exists in part for that reason.
(c) Copyright 2019 Palantir Technologies Inc. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.
Original work copyrighted by Google under the same license:
Copyright 2015 Google Inc.
Licensed under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.