To follow up on my post yesterday about fine tuned suppressions, I thought I would give an example. Below is what I have defined in the Checkstyle rules file: 

  <!-- Look for use of standard out/error. Want to be able
       to suppress this, so define an id.
  -->
  <module name="GenericIllegalRegexp">
    <b><property name="id" value="consoleOutput"/></b>
    <property name="format" value="System\.((out|err))\."/>
    <property name="message" value="Use a logger."/>
  </module>

  <!-- Look for trailing whitespace. IDE's add it all the time,
       causing problems merging branches in Subversion. Never
       want to turn this off.
  -->
  <module name="GenericIllegalRegexp">
    <property name="format" value="\s$"/>
    <property name="message"
              value="Trailing whitespace causes merge HELL!"/>
  </module>

So now it is possible to just suppress the warning about logging to the console, but still check for trailing whitespace. As an example: 

  <!-- allow logging to console in database tools -->
  <suppress id="consoleOutput"
            files="[/\\]db[/\\]src[/\\]java[/\\]"
            />