Re: Handling a change in system date
james wrote:
Hi all,
I'm relatively new to java so I apologise if this is a simple
question. I am trying to detect when the system date changes so that I
can start a new log file for each day. I have setup the code to create
a new log file etc. however I can't seem to find any information on
how to detect changes in the system date. I am only interested in when
the day changes (not the time etc.) and I have looked into change
listeners however I'm not sure if this is the right approach or not?
One way is to insert the date check in the logging code:
Each time you log a new message, first check for a date change
and possibly start a new log. This method is simple, but may
not be appropriate if the change-the-log code writes log messages
of its own, or if the logging code is mostly a "black box" whose
innards are hard to get at. (If you're using the java.util.logging
package, consider doing this by extending FileHandler.)
Another way is to use a separate thread to manage the change.
Each time you open a log file (at program start or when switching
log files), calculate the amount of time remaining until the next
midnight and set up a Timer to run the log-change activity then.
This separates the log-change from the rest of the logging, but
requires that you be careful about synchronizing things. Also,
Timer is not guaranteed to be 100% accurate, and you may switch
logs a few seconds early or late.
A variation on the second method: Use a repeating Timer to
wake up and check the date every minute or so, either changing
the log file or sticking with the old one.
--
Eric Sosman
esosman@ieee-dot-org.invalid