By cbeckham on Feb 15, 2005
Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard. It automates the process of checking Java code to spare humans of this boring (but important) task. This makes it ideal for projects that want to enforce a coding standard. Checkstyle is highly configurable and can be made to support almost any coding standard. An example configuration file is supplied supporting the Sun Code Conventions. As well, other sample configuration files are supplied for other well known conventions. A good example of a report that can be produced using Checkstyle and Maven can be seen here.
nbCheckstyle is an installable module for Java Studio Enterprise (NB3.6) and NetBeans which provides integration with Checkstyle. Checkstyle is an excellent tool for helping developers keep to a given coding standard.
Here are the rules that were defined for the Belgian Federal Gov. https://jjguidelines.dev.java.net/.......also you can see Code Conventions for the Java Programming Language from Sun here