Log for java aka log4j is a library. Its a small software that need to be downloaded an installed. The installation which I am going to illustrate if for Linux and a similar procedure can be followed for windows. It can be downloaded from the following link -
http://www.apache.org/dyn/closer.cgi/logging/log4j/1.2.15/apache-log4j-1.2.15.tar.gz
Download the tar file and extract it using the following command
tar -xvvzf apache-log4j-1.2.15.tar.gz
Move the for apache-log4j-1.2.15 to the a location of your choice. But I recommend you to put it in a folder where you have installed java (say you have moved the extracted the folder to /usr/java/). Now, the jar file log4j is inside the folder. The path should be
/usr/java/apache-log4j-1.2.15/log4j-1.2.15.jar
After this there are two ways to make it recogniseable by you java program. One is you need to set the CLASSPATH. The second and the best alternative is, you could import that jar file. I guess most of you use NetBeans or Eclipse for java programming. So all you need to do is to imort this jar file and it will be recognised by you package. If you want to know how to use logger function, read the following manual
