code: public final void errorf(String message, Object... args)
      {
          logf(Level.ERROR, null, message, args);
      }
docs: Logs a formatted message if ERROR logging is enabled.
  
  @param message a <a href="http://download.oracle.com/javase/6/docs/api/java/util/Formatter.html#syntax">format string</a>
  @param args    arguments referenced by the format specifiers in the format string.