A simple example of log4j

This Example shows you how to create a log in a program.

A simple example of log4j

A simple example of log4j

     

This Example shows you how to create a log in a program.

Description of the code:
  1. Logger.getLogger(): Logger class is used for handling the majority of log operations and getLogger method is used for return a logger according to the value of the parameter. If the logger already exists, then the existing instance will be returned. If the logger is not already exist, then create a new instance.
       
  2. Logger.debug(): This method is used to check that the specified category is DEBUG enabled or not, if yes then it converts the massage passed as a string argument to a string by using appropriate object renderer of class ObjectRenderer.
      
  3. Logger.info(): This method is used to check that the specified category is INFO enabled or not, if yes then it converts the massage passed as a string argument to a string by using appropriate object renderer of class ObjectRenderer.
      
  4. Logger.warn(): This method is used to check that the specified category is WARN enabled or not, if yes then it converts the massage passed as a string argument to a string by using appropriate object renderer of class ObjectRenderer.
      
  5. Logger.error(): This method is used to check that the specified category is ERROR enabled or not, if yes then it converts the massage passed as a string argument to a string by using appropriate object renderer of class ObjectRenderer.
      
  6. Logger.fatal(): This method is used to check that the specified category is FATAL enabled or not, if yes then it converts the massage passed as a string argument to a string by using appropriate object renderer of class ObjectRenderer.

LogExample.java


import org.apache.log4j.Logger;

public class LogExample {

  public LogExample() {
  }
  static Logger log = Logger.getLogger(LogExample.class);

  public static void main(String argsp[]) {

  log.debug("Here is some DEBUG");
  log.info("Here is some INFO");
  log.warn("Here is some WARN");
  log.error("Here is some ERROR");
  log.fatal("Here is some FATAL");
  }
}

log4j.properties


log4j.rootLogger=debug, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%5p] %d{mm:ss} 
(%F:%M:%L)%n%m%n%n


Output:
[DEBUG] 55:17 (LogExample.java:main:11)
Here is some DEBUG

[ INFO] 55:17 (LogExample.java:main:12)
Here is some INFO

[ WARN] 55:17 (LogExample.java:main:13)
Here is some WARN

[ERROR] 55:17 (LogExample.java:main:14)
Here is some ERROR

[FATAL] 55:17 (LogExample.java:main:15)
Here is some FATAL

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