See Checkstyle in Action

Configure a rule, run Checkstyle against your Java source, and get a precise violation.

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN" "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStarImport"/>
  </module>
</module>

import java.util..*;
class Test {
  List names;
}

$ java -jar checkstyle-13.11.0-all.jar
    -c config.xml Test.java
[ERROR] Test.java:1:1: Using the '.*' form
    of import should be avoided - java.util.*.
    [AvoidStarImport]

Learn more about configuration and running Checkstyle.

What can Checkstyle check?

View all checks →

class myClass {}

class MyClass {
  public void method() {}
}

if (retries > 3) {
  throw new RuntimeException();
}

// Missing javadoc
public void method() {}

public void method()
{
  // code
}

Make Checkstyle yours

Adopt an established configuration as a practical starting point, or define exactly which rules apply to your codebase.

Use it in your workflow

One configuration, everywhere it needs to run — your build, your terminal, and your CI pipeline.

Checkstyle also plugs into your CI/CD pipeline. See the Active Tools.

Ready to try Checkstyle?

Choose an integration above, adopt a supplied configuration or write your own, and run Checkstyle against your Java sources. Current release is 13.11.0.

Get Started Configuration Browse Checks

Download the latest release from the GitHub releases page or Maven Central . To build from source, check out the development code on GitHub or use jitpack.io to build artifacts directly, even from your own fork.

Previous Version Documentation

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.

Development Cycle

• happens at the end of each month if functional changes exist in the master branch of our repo
• can happen by request by any user who is impacted, but it is not always guaranteed.

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.

JRE and JDK

Runtime of Checkstyle is limited only by minimal version or JRE.

Checkstyle currently is confirmed to be buildable by all JDKs from 21 through 25. Most recent JDKs may be supported. Please report an issue if there are any problems with recent JDKs.

Supported Java Language Version

Checkstyle can parse all Java language features introduced in Java 22 and below. We may support preview features depending on community demand.

Please report an issue if you encounter any issues with the support of the latest Java language features.

Limitations

Checkstyle is a single file static analysis tool, for more details please read the full list of limitations.

Additional Checks

There are other projects that provide additional checks:

Related Tools

Checkstyle is most useful if you integrate it into your build process or your development environment. The distribution includes:

• An Ant task.
• A command line interface (CLI).

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:

Active Tools

Inactive or Old Tools