How to enable debug in slf4j Logger?

Question

How to globally enable debug for all the slf4j.Logger objects?

Answer 1

exists various capability to switch debug log on:
this article have good explanation all of those. to me good fit is:

Using slf4j with Log4j logger
create file src/main/resources/log4j.properties

log4j.rootLogger=DEBUG, STDOUT
log4j.logger.deng=INFO
log4j.appender.STDOUT=org.apache.log4j.ConsoleAppender
log4j.appender.STDOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.STDOUT.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n