What is Log4J?

What is Log4j?

 It is an open source logging tool, given by apache to use as an alternative for System.out.println (““) statements in a java project.

It has 3 main components to work with Log4j

1) Logger Object

2) Appender Object

3) Layout Object

Logger:

Logger Object is responsible for capturing logging messages generated at execution time of an application.

•         Logger is a class, in org.apache.log4j.*

•         We need to create Logger object one per java class.

•         Logger class methods are used to generate log statements in a java class instead of System.out.println(“”) statements;

static Logger logger=Logger.getLogger (String classname);

static Logger logger=Logger.getLogger (Class clazz);

getLogger () method is a static factory methods .its returns a class object.

Logger object has some methods; actually we used to print the status of our application by using these methods only

We have a method in Logger class

•         debug()

•         info()

•         warn()

•         error()

•         fetal()

As a programmer it’s our responsibility to know where we need to use what method.