How to use Logger in our JAVA simple projects / Programs

Simple way to use logger in our project

Steps to use :

1.) Download log4j jars link is lo4j.jars
2.) Try sample project in Eclipse or run normally link to download is Sample Logger Project


Sample program looks like :-

package TestLogger;
import java.io.IOException;
import Logger.LoggerInstance;

public class SampleClass {

public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
LoggerInstance loggerObj = new LoggerInstance();
System.out.println("Hello World");
LoggerInstance.logger.info("Hello World");
}
}

To use these Logger Instance we need to define separate class that you can find in dummy project or refer below class :-

package Logger;

import java.io.File;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;

public class LoggerInstance {

public static Logger logger;
File directory = new File ("");
String absolutepath = directory.getAbsolutePath();
//This is to get location for creating log file. This value is comming from build.xml
String str_logFilePath = absolutepath+File.separator+"log";


public LoggerInstance() throws IOException
{
DateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
Date date = new Date();
System.out.println(date);
String current_dateTime = dateFormat.format(date);
System.out.println(current_dateTime);
current_dateTime = current_dateTime.replace("-", "_");
current_dateTime = current_dateTime.replace(" ", "_") ;
current_dateTime = current_dateTime.replace(":", "_") ;

File f1 = new File(str_logFilePath) ;
if(!f1.exists()){
f1.mkdir();
}
//System.out.println("00 " + str_logFilePath);

String str_logFilePath1 = str_logFilePath+File.separator+"LogFile_created_by_ASJ_"+current_dateTime+".log";
//System.out.println("11 " + str_logFilePath1);

File f2 =  new File(str_logFilePath1);
f2.createNewFile();


if(logger==null)
{
try{
logger = Logger.getLogger("ASJ");
FileAppender apndr = new FileAppender(new PatternLayout("%p %t %c - %m%n"),str_logFilePath1,true);
//apndr.setAppend(true);
logger.addAppender(apndr);
}
catch(Exception e)
{
System.out.println("Log file is not initialized");
}
}
}

}

So it is easy to run :-)