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CheckStyle plug-in for IntelliJ IDEA
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© Copyright 2006-2015 CheckStyle-IDEA Contributors

Hosted on GitHub

A plug-in for JetBrains' IntelliJ IDEA 14.1 which provides real-time feedback against a given CheckStyle profile by way of an inspection.

Released under a BSD-style licence - please see the LICENCE file for details.

OS X users please note - CheckStyle 6.2 and above require Java 8. As the default IDEA package for OS X runs on Java 6, please make use of the versions with the bundled JDK, e.g.

or, for Brew Cask users,

  • brew cask install intellij-idea-ce-bundled-jdk
  • brew cask install intellij-idea-bundled-jdk

All other users please note - we require IDEA to be running on JDK 8.


Once installed, a new inspection will be available in the group 'CheckStyle'. The 'Inspections' item in the preferences panel will allow you to turn this on and to configure it.

Project exceptions are treated a little oddly. Because CheckStyle demands these to be on the current classpath errors will appear if these have not as yet been compiled. Further, because we cache the real-time checkers for performance reasons, real-time scans may continue to show the errors after a compilation. A static scan will force a reload of the Checker and should resolve this.


Configuration is available under the Settings dialogue. This controls configuration for both the inspection and static scanning.

Configuration Files

The main configuration option is that of the CheckStyle file. Multiple CheckStyle file may be added, and swapped between by using the checkbox. Files may be added using the 'Add' button.

The Scan Test Classes checkbox will enable scanning of Java files under test source roots. If disabled, these files will be ignored.

If a custom file is being used and properties are available for definition then these will accessible using the 'Edit Properties' button.

Third Party Checks

This tab allows you to specify any third-party checks which your configuration file makes use of. All selected directories/JAR files will be added to CheckStyle's classpath.


If an error occurs during the check an exception will be thrown, which IDEA will then catch and display in the standard exceptions dialogue. If you're unsure as to why things are awry this would be your best bet - chances are it's a missing property or classpath pre-requisite.

Notable Extensions


sevntu.checkstyle offers a number of useful checks written by students of the Sevastopol National Technical University (SevNTU). They're also kind enough to offer instructions on setting them up with this plugin.

Checkstyle Addons

Checkstyle Addons offers additional Checkstyle checks not found in other Checkstyle extensions, and it's easy to set up in Checkstyle-IDEA.


Note that the plugin has been entirely developed on OS X - while it should be fine on Linux, I've no idea what result you'd get with Windows. YMMV.

The pre-requisites for the plugin are fairly light - you'll need Git; JDK 1.8.x and IntelliJ 14.

git clone checkstyle-idea
cd checkstyle-idea

Then edit gradle.properites to point at your local installation of IDEA and at your plugin directory. The defaults should be suitable for IDEA 14 on OS X.

You can then easily build and install the plugin via Gradle:

./gradlew clean installPlugin

This will build the plugin to build/distributions/checkstyle-idea-<version>.zip and install the plugin to your local IDEA.

You can also build (and more importantly work on) the plugin via IDEA. There is a project file supplied, however it is targetted at OS X so some paths may be incorrect. You'll also need to have set up an IntelliJ Platform Plugin SDK if you haven't before - you can do this in Project Structure, under SDKs, just as you would for a JVM.

Frequently Asked Questions

I see a Cannot Load Project error stating Unsupported major.minor version 52.0.

The plugin is compiled using language level 1.8, and hence must be run on Java 8. This is because CheckStyle 6.2 and above require at least JVM 1.7, and because I like lambdas.

If you're on OS X, use IDEA with the bundled JVM. Otherwise, please ensure IDEA is running using Java 8 or later. Jetbrains offer a support document on this subject.

I see 'Got an exception - java.lang.RuntimeException: Unable to get class information for . (0:0)'

CheckStyle is unable to retrieve information on exceptions in your project until you have built it. Build your project in IDEA and then rescan.


  • The plugin will throw exceptions if used with class files targeted at a later version than that of the JDK used by IDEA. Please run IDEA on the latest available JVM, ideally the bundled version from JetBrains where available. Thanks to J. G. Christopher.
  • If you change the configuration options the real-time scan will not be updated until the file is either changed or reopened.
  • We do not check if a property definition is required for a given file. Hence you can exit configuration without setting required properties. Given, however, that CheckStyle files can change without the plug-in being aware this is something we'll always have to live with to some degree.
  • CheckStyle errors and warnings from the inspection are both shown at a single level, as IDEA will only allow one warning level for an inspection.


The following are potential features which are likely to be investigated for future releases.

  • Scan selected files/folder in the project panel.
  • Better error feedback.


Any comments or bug reports are most welcome - please visit the project website on GitHub.


This plug-in owes its existence to both the style-overlords at work mandating compliance with a CheckStyle configuration, and the Eclipse-CS authors for making me jealous of the real-time scan support available for Eclipse.

Thanks to those who have contributed work and effort directly to this project:

  • J. G. Christopher
  • jicken
  • Jonas Bergvall
  • Edward Campbell
  • LightGuard.JP
  • Gerhard Radatz
  • Benjy W
  • Yuri
  • Kristin Young
  • Simon Billingsley
  • Miel Donkers
  • Dmitrij (zherebjatjew)
  • Thomas Jensen

And also thanks are due to the authors and contributors of:

  • Eclipse-CS, for inspiration and solutions to coding problems.
  • JetStyle, for filling the area of static scanning and also giving me inspirations on coding solutions.
  • CheckStyle, for without them we'd have merely void and chaos.
  • JetBrains, for an IDE which is worth every penny and then some.

And a big thank-you to everyone who's sent me feedback or bug reports - both are much appreciated!


This code is released under a BSD licence, as specified in the accompanying LICENCE file.

Version History

  • 4.21.2 Fixed: Fixed thread access issue with module lookup in inspection (#200).
  • 4.21.1 Fixed: Now properly swallows parse errors from Checkstyle 6.12.
  • 4.21.0 New: Updated to CheckStyle 6.12.1.
  • 4.20.1 Fixed: Inspection now checks for cancellation (#192).
  • 4.20.1 Fixed: Rules accessed via HTTP no longer use temporary files (#67).
  • 4.20.0 New: Updated to CheckStyle 6.11.2 (#189).
  • 4.19.1 Fixed: Improved handling of unparsable files (#185).
  • 4.19.0 New: Updated to CheckStyle 6.10.1.
  • 4.18.1 Fixed: Prefix added to inspection messages (#181).
  • 4.18.0 New: Updated to CheckStyle 6.9.
  • 4.17.3 Fixed: Temporary suppression of exception in #127 until it's fixed in CheckStyle.
  • 4.17.3 Fixed: Started reducing the embarrassing amount of duplicated code.
  • 4.17.2 Fixed: Errors are also now entered in the event log, so they can be read after the balloon popup closes.
  • 4.17.2 Fixed: Modernised how notifications are raised.
  • 4.17.1 Fixed: Java source files that are marked as generated are no longer scanned (#172).
  • 4.17.1 Fixed: Properties are properly reloaded after hitting previous in the add file wizard (#170).
  • 4.17.0 New: Updated to CheckStyle 6.8.1.
  • 4.17.0 Fixed: TreeWalker logs are now suppressed, reducing event log spam when editing files (#169).
  • 4.17.0 Fixed: Inspection no longer overrides getShortName as per the IDEA source docs - this has resulted in a ShortName change (#173).
  • 4.17.0 Fixed: Only files in the project content source are scanned (#172).
  • 4.17.0 Fixed: Mirrored JAR files are now used when available (#141).
  • 4.17.0 Fixed: Modernised resource bundle usage.
  • 4.16.0 New: Updated to CheckStyle 6.7 (#168).
  • 4.15.0 New: Updated to CheckStyle 6.6 (#150).
  • 4.14.2 Fixed: Cached checkers are now cleaned by a background task (#141).
  • 4.14.2 Fixed: Updated icons to more closely resemble current CheckStyle icon.
  • 4.14.2 Fixed: File writes are now forced to UTF-8 (#84).
  • 4.14.1 Fixed: HTTP rules files should result in fewer temporary files (#149).
  • 4.14.1 Fixed: findFile now uses ReadAction (#140).
  • 4.14.0 New: Moved to CheckStyle 6.5, which requires Java 7 or above.
  • 4.14.0 New: Moved to Java 8. Please make sure IDEA is running on JDK 8. OS X users must use the 14.1 build with the bundled JDK.
  • 4.14.0 New: As such, we now use the IDEA 14.1 SDK.
  • 4.13.2 New: Reverted to IDEA 13 SDK, as when IDEA 14.1 drops with Java 8 for OS X users there's going to be an SDK update anyway.
  • 4.13.2 Fixed: Third party classes were not available in dialogue editors. (#133).
  • 4.13.1 Fixed: Became paranoid about ToolWindow implementation classes to avoid ClassCastExceptions (#131).
  • 4.13.0 New: Moved to IDEA 14 SDK.
  • 4.12.0 New: Files can now be selected from within JAR files (#125).
  • 4.11.2 Fixed: Changed configuration storage to use a sorted map, to stop silly changes to project files.
  • 4.11.2 Fixed: Configuration files are now sorted by description in the configuration panel.
  • 4.11.2 Fixed: Filename defaults should now be taken into account (#119).
  • 4.11.2 Fixed: Cell edits in properties table are now directly committed on action (#119).
  • 4.11.1 Fixed: ClassCast on ToolWindow via presumed race condition (#82).
  • 4.11.0 New: Updated to CheckStyle 6.1.1 (#124).
  • 4.11.0 Fixed: Made DTDs for import_control 1.1 and packages 1.0 available for offline access (#123).
  • 4.10.0 New: Updated to CheckStyle 6.1 (#120).
  • 4.9.0 New: Updated to CheckStyle 6.0 (#116).
  • 4.8.0 New: Updated to CheckStyle 5.9 (#115).
  • 4.7.0 New: Updated to CheckStyle 5.8 (#114).
  • 4.6.2 Removed commons-logging from plugin classpath (#113).
  • 4.6.1 Rules files may now have extension 'checkstyle' (#112).
  • 4.6.0 Fixed caching of project relative locations between projects (#106).
  • 4.6.0 Moved to IDEA SDK 133.696 (13.0.2).
  • 4.5.5 Fixed: Project base directory is no longer permanently cached (#106).
  • 4.5.4 Fixed: Null check for view; thanks to Miel Donkers (#104).
  • 4.5.3 Fixed: Added range check for line numbers (#100).
  • 4.5.2 New: When adding a HTTPS location you can now choose to ignore certificate errors (#99).
  • 4.5.2 Fixed: HTTP basic auth is now supported for URLs with a username/password (#93).
  • 4.5.2 Fixed: Better handling of NPE case (#97).
  • 4.5.1 Fixed: NPE on new project (#97).
  • 4.5.0 New: Updated to CheckStyle 5.7 (#95).
  • 4.5.0 New: Build is now performed via Gradle and hence should be consistent.
  • 4.5.0 Improved: Temporary file paths are now built relative to the module rather than just the package (#92).
  • 4.4.3 Fixed: Clash with IDEA's project path encoding (#88).
  • 4.4.2 Fixed: NPE when DoubleCheckedLocking file is added via config panel (#86).
  • 4.4.2 Fixed: Rules files are now blacklisted for 60s if they fail on load (#76).
  • 4.4.2 New: No default rules file is applied by default (#83).
  • 4.4.1 Fixed: Added a work-around for the API not respecting focus for split editors (#78).
  • 4.4.1 Fixed: ScanCurrentFile now works from the editor if the tool window has not yet been shown (#82).
  • 4.4.1 Fixed: File paths in ImportControl statements are now filtered (#77).
  • 4.4.1 Fixed: File choosers now work with Darcula; thanks to Simon Billingsley (#74).
  • 4.4.1 Fixed: Use configured third-party classpath when creating a test checker to validate the configuration; thanks to Simon Billingsley (#79).
  • 4.4 Improved: Adding rules files now validates the file before committing.
  • 4.4 Improved: Preferences UI improved.
  • 4.4 New: Scan toolwindow now allows quick selection of a configured rules file.
  • 4.3.1 Fixed: Error with ToolWindows on project load.
  • 4.3 New: IDEA build 129.677 or above is required, due to breaking changes in the API (ProblemDescriptor in 99b786ddb if you're nosy).
  • 4.3 Fixed: Scan option should now appear but once in the check-in dialogue (#68).
  • 4.3 Fixed: Better handling of IDEA exceptions during background scanning (#62).
  • 4.3 Plug-in modernisation work.
  • 4.2 New: There is now a specific option to make rules files project relative (#60).
  • 4.2 Fixed: Suppression files accessed via HTTP(S) now work again; thanks to Kristin Young (#61).
  • 4.1 New: There is now a configuration option to stop CheckStyle errors being display as IDEA errors (#50).
  • 4.1 New: A warning is now displayed for rules files using DoubleCheckedLocking.
  • 4.1 Fixed: Case of file prefix should now no longer randomly change (#59).
  • 4.0.2 Fixed: Module classpath should only expose classes, not resources (#56).
  • 4.0.2 Fixed: IllegalArgumentException sometimes thrown by CheckerFactory.getConfig (#55).
  • 4.0.2 Fixed: ToolWindow icon is now 13x13 pixels (#52).
  • 4.0.1 Fixed: NPE on Checker lookup (#49).
  • 4.0.1 Fixed: Read Access error (#39).
  • 4.0 New: You can now specify template CheckStyle configuration in the Default Project (#33).
  • 4.0 New: CheckStyle errors will now be marked as errors by the inspection.
  • 4.0 New: Updated to IDEA 12 API. . This means we now require IDEA 12.0.1 or above.
  • 4.0 Improved: Updated plugin structure to something a little more modern, allowing goodies such as #33.
  • 4.0 Fixed: Dependent modules are now probably included when searching for custom exceptions (#42).
  • 3.9.1 Fixed: Default rules are invalid with CS5.6.
  • 3.9 Fixed: Match on leading project path causes tokenisation silliness (#9).
  • 3.9 New: Updated CheckStyle to 5.6.
  • 3.8.4 Fixed: IDE error on pre-check-in scan (#39).
  • 3.8.3 Fixed: Synchronisation issue introduced by earlier fix (#36).
  • 3.8.2 Fixed: Library classes are now included in the Checkstyle classpath (#34).
  • 3.8.2 Fixed: Removed actions not specific to the current editor from the popup menu (#31).
  • 3.8.2 Fixed: Changed text to match IDEA by removing full-stops (#30).
  • 3.8.1 Fixed: Inline regexp header defs no longer cause an exception (#29).
  • 3.8 New: An option has been added to scan all (i.e. non-Java) files.
  • 3.8 New: A button has been added to scan the current change list.
  • 3.8 New: Modules can now be excluded from scans.
  • 3.8 New: Add File dialogue now sets the base directory to the project directory.
  • 3.8 Improved: RegexpHeader.headerFile is now resolved in the same manner as the suppression file.
  • 3.8 Improved: Rewrote file tokenisation to hopefully help with #9.
  • 3.7 New: Updated CheckStyle to 5.5.
  • 3.7 New: Added button to trigger rules refresh (#25).
  • 3.7 Fixed: Assertion errors from IDEA are now ignored during Inspections executions (#22).
  • 3.7 Fixed: Scan on check-in broken in IDEA 11 (#24).
  • 3.6.2 Improved: Scan results are now sorted alphabetically.
  • 3.6.2 Fixed: Duplicate errors reported during project scans (#16).
  • 3.6.2 Fixed: Edited rule file properties are now properly saved.
  • 3.6.1 Fixed: Deadlock when trying to access editor information with IDEA 11.
  • 3.6 New: Changed to work with IDEA 11. Thanks to Yuri.
  • 3.5 New: Updated CheckStyle to 5.4.
  • 3.5 Fixed: NPE during property handling.
  • 3.5 Fixed: Property change detection improved.
  • 3.5 Improved: General cleanup and deprecation removals.
  • 3.4.1 Fixed: Intermittent NPE on check-in handler registration.
  • 3.4 New: Support for IDEA 10.5. Older versions are no longer supported.
  • 3.3.2 Fixed: Relative paths for suppression filters were not working.
  • 3.3.1 Fixed: StringIndexOutOfBoundsException when creating temporary files under Windows.
  • 3.3 Improved: Suppression filters now work on package paths.
  • 3.3 Improved: Closed and saved files are no longer copied to temporary files.
  • 3.2 New: Updated CheckStyle to 5.3.
  • 3.2 Improved: Temporary files now use original filename. Thanks to Benjy W.
  • 3.2 Improved: Removed deprecated calls to IDEA SDK. This may break compatibility with older versions, but as the SDK isn't annotated with @since, who knows?
  • 3.2 Improved: Introduced setup thread to project scans to improve responsiveness.
  • 3.1.2 Fixed: Property names trimmed.
  • 3.1.2 Fixed: Cache is now invalidated when settings are changed.
  • 3.1.2 Fixed: Files downloaded via HTTP are now scheduled for deletion of JVM termination.
  • 3.1.1 Fixed: NPE on notifications.
  • 3.1 New: Upgraded to CheckStyle 5.1.
  • 3.1 Improved: Suppression files are now searched for relative to the project if they are not present relative to the config file.
  • 3.1 Improved: If a suppression file is not found then it will be ignored and the user will be warned.
  • 3.1 Fixed: Concurrency issues. Thanks to Gerhard Radatz.
  • 3.0.13 Fixed: File location fixes galore! Thanks to Gerhard Radatz.
  • 3.0.13 Fixed: Removing active configuration no longer causes an exception. Thanks to Gerhard Radatz.
  • 3.0.12 Fixed: Inspection ID now correctly conforms to rules. Apologies if this breaks inspection config.
  • 3.0.11 Improved: Module/Project scans are properly batched and a lot faster. Progress feedback is more limited, however.
  • 3.0.10 Fixed: Partial property detection. Thanks to LightGuard.JP.
  • 3.0.9 Fixed: Cache sychronisation problem.
  • 3.0.8 Fixed: Null property in configuration hash-table resulting in NPE.
  • 3.0.7 Fixed: Module scan results are no longer shared between files.
  • 3.0.6 Fixed: IDEA 9 compatibility.
  • 3.0.5 Fixed: Filters (e.g. SuppressionCommentFilter) now work correctly.
  • 3.0.5 Fixed: JavadocPackage now respects allowLegacy. Thanks to Edward Campbell.
  • 3.0.4 Fixed: CheckStyle DTD 1.3 added. Thanks to Jonas Bergvall.
  • 3.0.3 Fixed: Removed dependency on Apache commons-lang to restore compatibility with IDEA 7.0.x/Linux.
  • 3.0.2 Fixed: File configuration column headings were incorrect.
  • 3.0.1 Fixed: Rule files added with no description cause an exception.
  • 3.0 New: Module-specific configuration support.
  • 3.0 New: CheckStyle 5.0 support. Thanks to jicken. Note that CheckStyle 5.0 is not entirely backwards compatible. A quick guide to many of the changes can be found here:
  • 3.0 New: Result list may be filtered on severity.
  • 3.0 New: Back-end re-written to support multiple CheckStyle files. You will need to set your configuration once again I'm afraid.
  • 2.4 New: Default CheckStyle file now has generics patch applied.
  • 2.4 New: Scans in progress may be aborted.
  • 2.4 Fixed: Null Pointer Exception with package HTML check.
  • 2.4 Fixed: Null Pointer Exception when files have no module.
  • 2.4 Fixed: Background scan thread does not wait on event thread.
  • 2.3 Fixed: Property values are not lost on configuration commit.
  • 2.3 Fixed: Exceptions in JAR files are not picked up.
  • 2.3 Fixed: Scan Modified Files is now disabled while other scans are active.
  • 2.3 Fixed: Background scan thread is now lower priority.
  • 2.3 Fixed: Module scan now works again.
  • 2.2 Fixed: Now works with IDEA8.0.
  • 2.2 New: Ability to scan on check-in. Thanks to J. G. Christopher.
  • 2.2 Experimental: Ability to load CheckStyle configuration from a URL. This is NOT robust at present.
  • 2.1 New: Ability to scan only modified files if project uses VCS. If the project does not use VCS then this action will have no effect. Thanks to J. G. Christopher for this patch.
  • 2.1 New: Ability to suppress checks on test classes.
  • 2.1 New: Updated CheckStyle to 4.4.
  • 2.1 Fixed: Suppression filters with relative paths now load correctly.
  • 2.1 Fixed: NewlineAtEndOfFile now works on Windows.
  • 2.1 Fixed: PackageHtml test will now work.
  • 2.0.1 WARNING: Due to persistence changes you will need to reconfigure the plug-in after upgrading.
  • 2.0.1 Fixed: Configuration dialogue now enables 'apply' when moving to default scheme from a configuration file.
  • 2.0.1 Changed: Remove deprecated API calls to [hopefully] ensure forward 7.0 compatibility.
  • 2.0.1 Changed: Icons improved.
  • 2.0.0 This version offers no new features. However, 2.x versions will only work with IDEA 7M2 or above.
  • 2.0.0 Fixed: API changes for IDEA 7M2.
  • 1.0.2 Improved: Error handling
  • 1.0.2 Fixed: Exception when settings opened while no project loaded.
  • 1.0.2 Fixed: Exception if inspection cancelled during results processing.
  • 1.0.2 Fixed: Exception if configuration panel opened while could not be accessed.
  • 1.0.1 Fixed: Potentially IllegalState if project path cannot be retrieved within IDEA 7M1.
  • 1.0 New: Static scanning for current module implemented.
  • 1.0 New: Ability to add third-party checks.
  • 1.0 New: Ability to define external properties.
  • 1.0 New: Now works with IDEA 7M1.
  • 1.0 Fixed: Exceptions defined in project will no longer generate a CheckStyle error once they have been compiled.
  • 0.5.2 New: Settings are now stored in project, not workspace.
  • 0.5.1 Fixed: NullPointer when a null PSI element is encountered during scanning.
  • 0.5 Improved: Localisation support.
  • 0.5 Improved: Config file locations under the project root are now stored as relative rather than the system-specific absolute path.
  • 0.5 New: CheckStyle icons added.
  • 0.4 New: Added static scanning support.
  • 0.4 New: Updated CheckStyle to 4.3.
  • 0.3 Improved: CheckStyle caching improved.
  • 0.3 Improved: Temporary file deletion.
  • 0.2 Fix: File browser for configuration file filters out directories.
  • 0.1 Initial release.
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