How to find the name of a failing checkstyle rule

Question

Checkstyle is balking at some code and I want to add a suppression rule. How do I find the name of the rule that is failing so I can specifically suppress that rule for this section of code?

Answer 1

If you are using the command line version of Checkstyle, the easiest way would be to look at the XML output report. Use -f xml to tell Checkstyle to output XML. Violation messages in XML look like this:

<error line="0" severity="error" message="Missing package-info.java file."
    source="com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocPackageCheck"/>

So here, the check name for use by the suppression filter is JavadocPackage.

For manual lookup, you have some further options:

• You could manually go to the list of available checks and search it for keywords from your violation message. (Thanks @crasp for pointing this out in the comments.)
• If you are using Eclipse, you can check the "Include rule names in violation messages" checkbox as described here to see the rule name in Eclipse.
• If you are using SonarQube, you can see the rule name by clicking on the issue.