Session2 :Log4j Examples

How to use log4j for you application ….
Try with following example(for running following example you need jar file)

First see main class

public class Main {

/** Creates a new instance of Main */
public Main() {
}

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
Sample sample = new Sample();
sample.doLogging();
}

}

Now see Sample class which has doLogging();

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

/**
*
* @author Administrator
*/
public class Sample {
Logger logger = Logger.getLogger(Sample.class.getName());

Logger logger1 = Logger.getLogger("Logger1");

/** Creates a new instance of Sample */
public Sample() {
}

public void doLogging() {
logger.debug("Test Logging logger1 DEBUG");
logger.info("Test Logging logger1 INFO");
logger.warn("Test Logging logger1 WARN");
logger.error("Test Logging logger1 ERROR");
logger.fatal("Test Logging logger1 FATAL");

logger1.debug("Test Logging logger1 DEBUG");
logger1.info("Test Logging logger1 INFO");
logger1.warn("Test Logging logger1 WARN");
logger1.error("Test Logging logger1 ERROR");
logger1.fatal("Test Logging logger1 FATAL");
}
}

Lets see” log4j.properties” file
Here two appenders(X and Y ) for ConsoleAppender and RollingFileAppender you can specify conversionPattern(This show patten for logging) as preferd(Ex: %d %C{2} %l %c %m %n)

The syntax for configuring the root logger is:
log4j.rootLogger=[level], appenderName, appenderName, ...

This syntax means that an optional level can be supplied followed by appender names separated by commas.
The level value can consist of the string values OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL or a custom level value. A custom level value can be specified in the form level#classname.

log4j.properties file

log4j.rootLogger = All,X
# Logger1 is a customLogger
log4j.logger.Logger1 = INFO,Y


log4j.appender.X=org.apache.log4j.ConsoleAppender
log4j.appender.X.layout=org.apache.log4j.PatternLayout
log4j.appender.X.layout.conversionPattern=%p %d %C{2} %l %c %m %n

log4j.appender.Y=org.apache.log4j.RollingFileAppender
log4j.appender.Y.layout=org.apache.log4j.PatternLayout
log4j.appender.Y.layout.conversionPattern=%p--%d - %C{2} - %l - %c %m %n
log4j.appender.Y.threshold=All
log4j.appender.Y.append=true
log4j.appender.Y.MaxFileSize=1KB
log4j.appender.Y.File=C:/Log.out

Try with above Example
END

java code for Autoboxing/Unboxing of Wrappers and Foreach and Generics

java code for Autoboxing/Unboxing of Wrappers

import java.util.List;
import java.util.LinkedList;

public class WorkOut1 {
private void test(final Integer[] intArray){
List myIntList = new LinkedList();

for (Integer integer : intArray) {
double dRandval = Math.random()*100;
Double dRandValWrapper = dRandval;//inboxing
myIntList.add(dRandValWrapper.intValue() + integer);

}

for (Integer integer : myIntList) {
System.out.println("Value : " +integer);
}

}

public static void main(String[] args) {
WorkOut1 workOut1 = new WorkOut1();
workOut1.test(new Integer[]{4,5,2,8,6,3,9,2});

}

}
--------------------------------------------------------------------------
Foreach and Generics

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.LinkedList;

public class WorkOut1 {
private void test(final Integer[] intArray){
List myIntList = new LinkedList();

for (Integer integer : intArray) {

Double dRandValWrapper =Math.random()*100;
myIntList.add(dRandValWrapper.intValue() + integer);

}

for (Integer integer : myIntList) {
System.out.println("Value : "+integer);
}

List ls = new ArrayList();


}

void printCollection(Collection c){

for (Object object : c) {
System.out.println(object);
}

}
// Collection c =new ArrayList();

public static void main(String[] args) {
WorkOut1 workOut1 = new WorkOut1();
//workOut1.test(new Integer[]{4,5,2,8,6,3,9,2});
List ls = new ArrayList();
ls.add("aaaa1");
ls.add("aaaa2");
ls.add("aaaa3");
ls.add("aaaa4");

workOut1.printCollection(ls);

}

}