orgslf4jsimpleLoggerdefaultLogLevel

org.slf4j.simple, commonly referred to as the SLF4J SimpleLogger, is the lightweight logging backend provided by the slf4j-simple module for the Simple Logging Facade for Java (SLF4J). It offers a compact, dependency-free implementation that writes log messages to standard error and is designed for small applications, prototyping, or testing environments where a full-featured logging framework is unnecessary.

Configuration and usage are performed via system properties at startup. The global log level can be set with org.slf4j.simpleLogger.defaultLogLevel, using values such as TRACE, DEBUG, INFO, WARN, ERROR, or OFF, with INFO being the default if not specified. Per-logger levels can be configured using org.slf4j.simpleLogger.log.<logger-name>, allowing finer control over logging output for specific packages or classes. Formatting options include org.slf4j.simpleLogger.showDateTime and org.slf4j.simpleLogger.dateTimeFormat to include timestamps, as well as org.slf4j.simpleLogger.showThreadName and org.slf4j.simpleLogger.showLogName to control the inclusion of thread and logger names in the output. The default output destination is standard error.

Binding and classpath considerations are important when using SLF4J. To utilize SimpleLogger, the slf4j-simple module must be on the classpath and should be the only SLF4J binding present; having multiple bindings on the classpath can trigger startup warnings or binding conflicts.

Advantages of this backend include ease of use and minimal dependencies, making it suitable for simple projects or quick tests. Limitations include a lack of advanced features found in other bindings (such as external configuration files, multiple appenders, or extensive formatting options). It is compatible with any code that uses the SLF4J API and requires careful management of classpath bindings to avoid conflicts.