Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard. It automates the process of checking Java code to spare humans of this boring (but important) task. This makes it ideal for projects that want to enforce a coding standard.
Checkstyle is highly configurable and can be made to support almost any coding standard. An example configuration files are supplied supporting the Sun Code Conventions, Google Java Style.
A good example of a report that can be produced using Checkstyle and Maven can be seen here .
Checkstyle can check many aspects of your source code. It can find class design problems, method design problems. It also has the ability to check code layout and formatting issues.
For a detailed list of available checks please refer to the Checks page.
The latest release of Checkstyle can be downloaded from the GitHub releases page, or Maven central.
If you want to live on the bleeding edge, you can checkout the current development code from GitHub and compile yourself. Or use jitpack.io to build and get artifacts you need (you can even build your forked repo).
The current website contains the documentation for the latest release only.
We only support this latest version.
You can find documentation for most old versions using a URL format like
https://checkstyle.sourceforge.io/version/X.X where "X.X" is the version number.
Example:
https://checkstyle.sourceforge.io/version/6.18
for version 6.18.
Checkstyle is following its own view of Hybrid Romantic and Semantic Versioning: This is in the form of "First.Second.Third"
First digit is representing Romantic version.
When it is the only number increasing, the maintainers marked it as
a noticeably large breaking compatibility
or major conceptual change which occurred from their perspective.
Second digit is Semantic version which is a combination of major and minor.
When it is the only number increasing, it means that
either some breaking compatibility happened
or new features/modules were introduced.
Third digit is Semantic version which is the patch version.
When it is the only number increasing, it means that only defects are fixed.
Checkstyle is not using Semantic Versioning due to the reason explained at issue #3709.
Runtime of Checkstyle is limited only by minimal version or JRE.
| Checkstyle version | JRE version |
|---|---|
| 10.x | 11 and above |
| 7.x, 8.x, 9.x | 8 and above |
| 6.x | 6 and above |
| 5.x | 5 and above |
Checkstyle currently is confirmed to be buildable by all JDKs from 11 through 17. Most recent JDKs may be supported. Please report an issue if there are any problems with recent JDKs.
Since Checkstyle 7, some users have been unable to continue upgrading to newer versions of the utility because of the new JDK compile requirements. The development team doesn't have the resources to keep updating the utility for older JDKs for those that can't work with the latest version.
However, some members of the community have created an unofficial backport of the latest Checkstyle releases to be run with older JDKs. It is not always an easy process and provided at the same release time as Checkstyle, but it tries to maintain a functional equivalent alternative.
| Backport version | Min. JRE version | Link |
|---|---|---|
| 10.0+ | 8 | github site |
| 7.0 - 8.45 | 6 | github site |
Checkstyle can parse all Java language features introduced in Java 22 and below. We may support preview features depending on community demand, but please note that support for a given preview feature may change at any time.
Please report an issue if you encounter any issues with the support of the latest Java language features.
Checkstyle is a single file static analysis tool, for more details please read the full list of limitations.
There are other projects that provide additional checks:
| Project name | Link | Remarks |
|---|---|---|
| Checkstyle addons | checkstyle-addons | |
| SevNTU checkstyle | sevntu-checkstyle |
Checkstyle is most useful if you integrate it into your build process or your development environment. The distribution includes:
Additionally plug-ins are written by third-parties. Some of them are still based on the Checkstyle 2.4 release, although there have been many improvements since then. The known plug-ins are:
| IDE / Build tool | Main/Initial Author | Available from | Remarks |
|---|---|---|---|
| Codacy | João Machado | codacy-checkstyle | Provides analysis per commit and per pull request. Supports CheckStyle config files. |
| Eclipse/RAD/RDz | Christian Wulf | Lightweight Eclipse Plugin for Quality Assurance Tools | Alternative to the Eclipse-CS plugin. Allows to use custom checks directly without providing an Eclipse Fragment plugin for that purpose. |
| Eclipse/RAD/RDz | David Schneider | Eclipse-CS Home Page | In 2007 was awarded Best Open Source Eclipse-based Developer tool . |
| Gradle | Hans Dockter (initial author) | Checkstyle supported out of the box | Gradle Checkstyle docs |
| IntelliJ IDEA | James Shiell | Checkstyle-idea Project Page | Provides real-time and on-demand scanning. |
| jGRASP | Larry Barowski | jGRASP Home Page | |
| Eclipse/RAD/RDz | Roman Ivanov | Project Page | Extension for Eclipse-CS plugin and also an incubator for Checkstyle checks that are not present in main stream of Checkstyle. See the Wiki and Blog . |
| Eclipse/RAD/RDz | Jan Burkhardt | Project Page | Extension for Eclipse-CS plugin which ensures nullness annotations on methods and constructors (JSR305). |
| Bamboo Checkstyle plug-in | Atlassian (formerly by Ross Rowe and Stephan Paulicke) | Bamboo Checkstyle plug-in Home Page | An add-on that will parse and record CheckStyle reports and report your style violations over time. |
| Code Climate | Sivakumar Kailasam | codeclimate-checkstyle | |
| Checkstyle GitHub Actions | Nikita Savinov | Github-action Marketplace | It runs checkstyle on your Pull Requests using github-actions and reviewdog |
| Jenkins Checkstyle plug-in | Jenkins Checkstyle plug-in Home Page | This plug-in is supported by the Static Analysis Collector plug-in that collects different analysis results and shows the results in aggregated trend graphs. | |
| Maven | Vincent Massol | Checkstyle supported out of the box | example report |
| tIDE | Built in | ||
| NetBeans | Petr Hejl | Checkstyle Beans | Problems with source code are displayed as annotations of the source |
| NetBeans | Software Quality Environment (SQE) | ||
| SonarQube | Freddy Mallet (initial author) | Checkstyle SonarQube repository | Demo site of SonarQube |
| jEdit | Todd Papaioannou | JEdit CheckStylePlugin | |
| IntelliJ IDEA | Jakub Slawinski | QAPlug | Provides quality assurance features. |
| JArchitect | JArchitect Home Page | Imports XML result files from CheckStyle. | |
| SBT | Andrew Johnson | sbt-checkstyle-plugin Project Page | SBT plugin for running Checkstyle on Java source files in an SBT project |
| code-assert | Stefan Niederhauser | code-assert | Assert that the java code of a project satisfies certain checks. Launch checkstyle validation from UTs |
| Emacs JDE | Markus Mohnen | Part of the standard JDEE distribution - | configuration could be seen at jdee-checkstyle.el |
| Visual Studio Code | Sheng Chen | vscode-checkstyle | Checkstyle for Microsoft Visual Studio Code |
| Mega-Linter | Nicolas Vuillamy | Checkstyle supported out of the box | Automatically detect 35 languages, 11 formats, 15 tooling formats and copy-pastes in your repository sources, and apply their related linters. Available as GitHub Action, other CI tools and locally |
| bld | Erik C. Thauvin | Checkstyle Extension for bld | An extension for checking source code in a bld project |
| IDE / Build tool | Main/Initial Author | Available from | Remarks |
|---|---|---|---|
| QALab | Benoit Xhenseval | QALab Home Page | Supports tracking Checkstyle statistics over time. |
| Vim editor | Xandy Johnson | Plugin Homepage | Vim file-type plug-in |
If you have written a plugin for other IDEs, please let us know, so we can provide a link here.
