logging the stacktrace

logging the stacktrace with log4j:

import org.apache.log4j.Logger;

import org.apache.log4j.PropertyConfigurator;

// ......

static Logger logger = Logger.getLogger(MyClass.class);

// ......

public static void debugException(Exception ex) {

    //ex.printStackTrace();

    logger.error("An error occurred in MyClass.", ex);

}

a simple log4j example

the properties file is something like that:

log4j.rootLogger=DEBUG


log4j.appender.SampleAppender =org.apache.log4j.FileAppender
log4j.appender.SampleAppender .File=Sample.log
log4j.appender.SampleAppender .layout=org.apache.log4j.PatternLayout
log4j.appender.SampleAppender .layout.ConversionPattern= [%t] %-5p %c{2} %d %x - %m%n


log4j.logger.org.sample=,SampleAppender 





import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;


public class Sample {


    static Logger logger = Logger.getLogger(Sample.class);



    public static void debug(String message, boolean debugModeOn) {
        if (debugModeOn) {
            PropertyConfigurator.configure("log4j.properties");
            logger.debug( message);
        }
    }




log4j.properties file must be in classpath..
for log format: http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/PatternLayout.html

logging in java apps

for starter, lets begin with java.util.logging..

http://www.java-tips.org/java-se-tips/java.util.logging/how-to-use-logger.html
http://www.rgagnon.com/javadetails/java-0501.html
http://www.roseindia.net/java/example/java/util/quintessential-logging-program.shtml

and log4j..
http://logging.apache.org/log4j/1.2/manual.html
http://www.basilv.com/psd/blog/2006/tips-for-using-log4j
http://homepage.mac.com/kelleherk/iblog/C1837526061/E2136921646/index.html

the interface:

package org.apache.log4j;

 public class Logger {

   // Creation & retrieval methods:
   public static Logger getRootLogger();
   public static Logger getLogger(String name);

   // printing methods:
   public void trace(Object message);
   public void debug(Object message);
   public void info(Object message);
   public void warn(Object message);
   public void error(Object message);
   public void fatal(Object message);

   // generic printing method:
   public void log(Level l, Object message);
}