Use the following to automatically use the current class name for the log category (example is for commons-logging, works with log4j, too):

   1  
   2  class Foo {
   3     private final Log log = LogFactory.getLog(getClass());
   4  }

Compare to the following where the class name is refered to explicitely. If the class is renamed or parts of the codes are copied ("reused") the logging will by misleading.

   1  
   2  class Foo {
   3     private static final Log log = LogFactory.getLog(Foo.class);
   4  }