import org.apache.log4j.Logger; import org.apache.log4j.Level; public class ExampleLogger { private static final Logger logger = Logger.getLogger(ExampleLogger.class.getName()); public static void main(String[] args) { logger.setLevel(Level.WARN); logger.warn("This is a warning log statement."); logger.error("This is an error log statement."); } }This code sets the log level to WARN, so only log statements with a level of WARN or higher (i.e. ERROR) will be output. The package library for org.apache.log4j is Apache Log4j, a logging utility for Java. It is an open source package that provides logging functionality for a wide range of applications.