What is the significance of log4j.rootLogger property in log4j.properties file? What happens if i don't use this property?

Question

What is the significance of log4j.rootLogger property in log4j.properties file? What happens if I don\'t use this property?

Example

Answer 1

To answer

What happens if I don't use this property?

If you don't set the rootLogger to a level and an appender, you will get a warning.

For example, if you omit or comment out the line log4j.rootLogger=DEBUG, stdout, i.e. say your log4j.properties file contains only the rootlogger and no additional loggers, here the root logger being commented out:

#log4j.rootLogger=DEBUG, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout

You will get something like the following output:

log4j:WARN No appenders could be found for logger (log4jtests.Log4jHelloWorld).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.