Checkstyle

Checkstyle examines Java source code against a chosen coding standard and flags code that breaks its rules. It automates the repetitive review work involved in keeping formatting and coding practices consistent across a project. Programmers can use its findings to bring individual files or an entire codebase into line with shared conventions. Its configurable checks can be adjusted to support many different Java coding standards.

Ready-made configuration files cover the Sun Code Conventions and Google Java Style, giving teams established rule sets to use as starting points. Projects can also tailor those checks to match their own standards instead of defining every rule from scratch. The tool is intended for Java developers and teams that need consistent source-code practices across collaborative or long-lived projects.

Checkstyle is distributed as a JAR and runs through the Java command. On Windows, the supplied checkstyle.bat file illustrates how to invoke that JAR with the command, while changes in the Java 8 package may mean setting the JAVA_HOME environment variable so the Java installation can be located. Published by checkstyle, version 6.18 is freeware for Windows.