import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class MyLibraryClass { private static final Logger logger = LoggerFactory.getLogger(MyLibraryClass.class); // ... } logger.debug("This is a debug message."); logger.info("This is an info message."); logger.warn("This is a warning message."); logger.error("This is an error message."); String username = "John"; logger.info("User {} logged in.", username); try { // code that may throw an exception } catch (Exception e) { logger.error("An error occurred.", e); }