debug log problem in java programing
old way1:
     System.out.println("LogonAction: User '" + username +
                      "' logged on in session " + sessionId);
*****************************************
old way2:
in java soruce file:
       if (log.isDebugEnabled()) {
            log.debug("LogonAction: User '" + username +
                      "' logged on in session " + sessionId);
        }
*****************************************
log4j: http://logging.apache.org/log4j/
in java source file:
     logger.info("LogonAction: User '" + username +
                      "' logged on in session " + sessionId);
*****************************************
JTracker: http://www.jtracker.net
in java source file:
    /*<<<TPID=TP001>>>*/
in jtracker case file:
   BPoint(TP=TP001){
    var.dis(username,sessionID);
    }
...
which solution does everyone seleted?

I usually use Log4j. You should pick the one that best suits your case.

Personally I always use Log4J. I have been thinking that perhaps I should use the commons-logging interface which enables me to transparently use Log4J or the logging mechanism in J2SEE 1.4, but I have never had any use for it.