Java.lang.NullPointerException

import java.sql.*;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import javax.swing.JFormattedTextField;
import javax.swing.JOptionPane;
import javax.swing.text.MaskFormatter;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;


/**
 *


* @author 

*/
public class appli extends javax.swing.JFrame {

/**


* Creates new form appli

*/

Connecter conn=new Connecter(); 
    Statement stm ;
     ResultSet rs;
     DefaultTableModel model=new DefaultTableModel(); 
    public appli() {



initComponents();


model.addColumn("nom");
   model.addColumn("prenom");
   model.addColumn("adresse");
   model.addColumn("telephone");
   model.addColumn("nchambre");
   model.addColumn("date_arrive");
   model.addColumn("date_sortie");
   model.addColumn("nbr_jour");
   try{ 
       stm=conn.obtenircnx().createStatement();
         //System.out.print("STM executer");
      System.out.print("executer");
      ResultSet rs=stm.executeQuery("SELECT * FROM reservation");



while (rs.next()){

model.addRow(new Object[]  {rs.getString("NOM"),rs.getString("PRENOM"),rs.getObject("ADRESSE"),rs.getInt("NBR_JOUR"
             )}); jTable1.setModel(model);

}
   }catch(Exception e){System.err.println(e+"non executer");}


}