log4jlogging
I am using log4j to log error and other system information. but come of the info logged twice at INFO level.
public static void main(final String... args) throws Exception {
LOGGER.info("program started");
try {
// try body codes
} catch (Exception ex) {
LOGGER.info("program start-up failed.",ex);
}
}
however when the program starts or failed the information logged twice, any one can help me to find what could be the reason of that.
In this particular case, Option 1 is better.
The guard statement (checking isDebugEnabled()) is there to prevent potentially expensive computation of the log message when it involves invocation of the toString() methods of various objects and concatenating the results.
In the given example, the log message is a constant string, so letting the logger discard it is just as efficient as checking whether the logger is enabled, and it lowers the complexity of the code because there are fewer branches.
Better yet is to use a more up-to-date logging framework where the log statements take a format specification and a list of arguments to be substituted by the logger—but "lazily," only if the logger is enabled. This is the approach taken by slf4j.
See my answer to a related question for more information, and an example of doing something like this with log4j.
This table might be helpful for you:
Going down the first column, you will see how the log works in each level. i.e for WARN, (FATAL, ERROR and WARN) will be visible. For OFF, nothing will be visible.
Best Answer
Looks like your messages are being logged once by the root logger and again by the specific logger as you may have both the appenders configured (may be at different places -in a properties file and then in code).
This can be solved by setting additivity to false on your logger. Log4j manual mentions additivity in the Appenders and Layout section.Check that out