Why do we declare Loggers static final?

Question

In Java, why is it best practice to declare a logger static final?

private static final Logger S_LOGGER

Answer 1

Actually static loggers can be "harmful" as they are supposed to work in a static context. When having a dynamic environment eg. OSGi it might help to use non-static loggers. As some logging implementations do a caching of loggers internally (AFAIK at least log4j) the performance impact might negligible.

One drawback of static loggers is eg. garbage collection (when a class is used only once eg. during initialization the logger will be still kept around).

For more details check:

• http://slf4j.org/faq.html#declared_static
• https://cwiki.apache.org/confluence/display/COMMONS/Logging+StaticLog

See also:

• Should logger be private static or not