log4j

This is the way of using log4j in java.

import org.apache.log4j.Logger;

private static Logger log = Logger.getLogger(ExternalAdvertiserAccountAssembler.class);

if (log.isDebugEnabled()) {
log.debug("User [id:"+ currentUser.getId() + "] is authorized to set the Trusted state.");
}

Links:
http://logging.apache.org/log4j/1.2/index.html