checkstyle

Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard. By default it supports the Google Java Style Guide and Sun Code Conventions, but is highly configurable. It can be invoked with an ANT task and a command line program. http://checkstyle.sourceforge.net/

Checkstyle is a tool for checking Java source code for adherence to a Code Standard or set of validation rules (best practices).

The latest release version can be found at SourceForge downloads or at Maven repo.

Each-commit builds of maven artifacts can be found at Maven Snapshot repository .

Documentation is available in HTML format, see http://checkstyle.sourceforge.net/checks.html. 
 
from https://github.com/checkstyle/checkstyle