Configuring log4j involves assigning the Level, defining Appender, and specifying Layout objects in a configuration file. The log4j.properties file is a log4j configuration file which keeps properties in key-value pairs. By default, the LogManager looks for a file named log4j.properties in the CLASSPATH. The level of the root logger is defined. So also, we can say that Slf4j and log4j are like abstraction class and interface in Java.. Sep 26, 2012 · Simple Logging Facade for Java (SLF4J) is an abstraction of different logging frameworks (eg. log4j, java.util.logging, commons logging etc.). This tutorial describes how to configure SLF4J with log4j as underlying logging framework. . So also, we can say that Slf4j and log4j are like abstraction class and interface in Java.. Sep 26, 2012 · Simple Logging Facade for Java (SLF4J) is an abstraction of different logging frameworks (eg. log4j, java.util.logging, commons logging etc.). This tutorial describes how to configure SLF4J with log4j as underlying logging framework.