Regardless of the logging framework in use (logback, log4j, commons-logging, java.util.logging, ...), loggers should be:
private
: never be accessible outside of its parent class. If another class needs to log something, it should instantiate its own
logger. static
: not be dependent on an instance of a class (an object). When logging something, contextual information can of course be
provided in the messages but the logger should be created at class level to prevent creating a logger along with each object. final
: be created once and only once per class. With a default regular expression of LOG(?:GER)?
:
public Logger logger = LoggerFactory.getLogger(Foo.class); // Noncompliant
private static final Logger LOGGER = LoggerFactory.getLogger(Foo.class);
Variables of type org.apache.maven.plugin.logging.Log
are ignored.