The Simple Logging Facade for Java or is intended to serve as a simple facade for various logging APIs allowing to the end-user to plug in the desired implementation at deployment time. SLF4J also allows for a gradual migration path away from Jakarta Commons Logging . Logging API implementations can either choose to implement the SLF4J interfaces directly, e.g. NLOG4J or SimpleLogger. Alternatively, it is possible to write SLF4J adapters for the given API implementation, e.g. Log4jLoggerAdapter or JDK14LoggerAdapter..