Easy way to use log4j

Installation

1. Get log4j: http://logging.apache.org/site/binindex.cgi
2. Unzip or untar the jarfile log4j-x.x.x.jar from the downloaded archive to the directory lib/ext/ of your Java installation.

Usage

1. Import log4j to any class file that needs logging:
   import org.apache.log4j.*;
   
   
2. Initialize the Logger once by setting the file name, the pattern and the log level:
   
   Logger.getRootLogger().addAppender(
    new WriterAppender(
        new PatternLayout("%d %8r [%t] %-5p %c %x - %m%n"),
        new FileWriter("[Put the name of the log file here.]", true)
    )
);
Logger.getRootLogger().setLevel(Level.toLevel(log level));

log level might be one of the following: "all", "trace", "debug", "info", "warn", "error", "fatal"
   
   
3. Use the logger whereever you need it:
   Logger.getRootLogger().trace("[Place your trace message here.]") or
   Logger.getRootLogger().debug("[Place your debug message here.]") or
   Logger.getRootLogger().info("[Place your info message here.]") or
   Logger.getRootLogger().warn("[Place your warn message here.]") or
   Logger.getRootLogger().error("[Place your error message here.]") or
   Logger.getRootLogger().fatal("[Place your fatal message here.]")

More information

• http://de.wikipedia.org/wiki/Log4j
• http://logging.apache.org/log4j/docs/api/index.html