Bonjour,
je veux extraire les données de ce fichier xml:

<?xml version="1.0" encoding="UTF-8"?>
<log>
<record>
  <date>2012-05-18T16:32:12</date>
  <millis>1337351532521</millis>
  <sequence>0</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>main</method>
  <thread>10</thread>
  <message>message1</message>
</record>
<record>
  <date>2012-05-18T16:32:12</date>
  <millis>1337351532557</millis>
  <sequence>1</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>fonction1</method>
  <thread>10</thread>
  <message>voila le message2 de la fonction1</message>
</record>
<record>
  <date>2012-05-18T18:15:33</date>
  <millis>1337357733396</millis>
  <sequence>0</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>main</method>
  <thread>10</thread>
  <message>message1</message>
</record>
<record>
  <date>2012-05-18T18:15:33</date>
  <millis>1337357733431</millis>
  <sequence>1</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>fonction1</method>
  <thread>10</thread>
  <message>voila le message2 de la fonction1</message>
</record>
<record>
  <date>2012-05-18T18:46:09</date>
  <millis>1337359569682</millis>
  <sequence>1</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>fonction1</method>
  <thread>10</thread>
  <message>voila le message2 de la fonction1</message>
</record>
<record>
  <date>2012-05-18T18:46:22</date>
  <millis>1337359582087</millis>
  <sequence>1</sequence>
  <logger>mon_projet</logger>
  <level>INFO</level>
  <class>test1.test1</class>
  <method>fonction1</method>
  <thread>10</thread>
  <message>voila le message2 de la fonction1</message>
</record>
 
</log>

J'ai utilisé ce code:

package convertion2;
import java.io.*;
import org.jdom.*;
import org.jdom.input.*;
import org.jdom.filter.*;
import java.util.List;
import java.util.Iterator;
import org.jdom.input.SAXBuilder;
 
import java.util.*;
 
 
public class convertion2 {
 
	static Document document;
    static Element racine;
    public  convertion2() {};
	public static void main(String[] args) {
 
 
	     SAXBuilder sxb = new SAXBuilder();
	     try
          {
 
	         document = sxb.build(new File("log.xml"));
          }
	      catch(Exception e){}
 
	      racine = document.getRootElement();
 
	      List<?> listEtudiants = racine.getChildren("record");
	      Iterator<?> i = listEtudiants.iterator();
	      while(i.hasNext())
	      {
 
	         Element courant = (Element)i.next();
 
	         System.out.println(courant.getChild("level").getText());
	      }
 
	}
}

Mais il m'affiche ce message d'erreur:
Exception in thread "main" java.lang.NullPointerException
at convertion2.convertion2.main(convertion2.java:41)
Je sais pas c'est quoi le problème.
Merci d'avance.