Avoding log4j logger statements in log files

We all have used log4j in multiple scenarios and it serves the purpose. There are cases when we don’t want the logger statements from few classes or few packages to clutter the log files. Some other cases, we want the logger statement to be printed in only one log file and not in all log files. These are 2 different cases and I will explain solution for both of the requirements.

Requirement 1: Don’t print the log statements in any of the configured log files. Consider a scenario where we have configured 4 -5 log files at different levels and for different purposes. If we don’t want the logger statement from the classes in a particular package or particular class to appear in any of these log files, we have to use the following syntax.

log4j.category.=OFF

e.g. log4j.category.com.test.welcome=OFF means that all the statements logged from the classes present in com.test.welcome package will not be logged in any of the configured log files.

Requirement 2: Don’t print the same log statements in all of the configured log files. It should be printed in the more specific log file only. Consider the scenario like this

log4j.category.com.pack1.pack2 = INFO, appender1

log4j.category.com.pack1 = INFO, appender2

The statements logged from the classes present in the package com.pack1 will be printed in the appender2 as well as appender1 log files as both of them satisfy the category. Now if we don’t want the logger statements from the pack2 not to print in appender1, then we can use the additivity clause.

# set additivity to false to ensure that the parent appenders do not log these statements
log4j.additivity.pack2 =false

The above line means that the logger statement from pack2 will be present only in appender1 log file and not in appender2 log file. This is because the logger file is configured for appender2 as well as appender1. That means the logger statement got printed only in the specific log file and not in its parent appenders.