Java.lang.NullPointerException at Procedure

Bonjour,
j'ai cette erreur je debute dans la programmation java, apres ma formation j'ai du creer un programme qui se connect à une base sql et qui execute une procedure stocké .Il se connecte bien mais j'ai une erreur
java.lang.NullPointerException at ProcedureStocke .main(ProcedureStocke.java :35)

voici mon programme

import java.sql.*;
import java.lang.*;

public class ProcedureStocke {

public static void main(String[] args) {

// Create a variable for the connection string.
String connectionUrl = "jdbc:odbc:logipro";

//integratedSecurity=false;";

// Declare the JDBC objects.
Connection con =null;
//Statement stmt = null;
ResultSet rs = null;
CallableStatement cstmt=null;
try {
// Establish the connection.
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

con = DriverManager.getConnection(connectionUrl,"admin","admin");



// Create and execute an SQL statement that returns some data.
String SQL ="{call creation_user}";
cstmt= con.prepareCall (SQL);

cstmt.execute();
//rs = cstmt.executeQuery(SQL);

// Iterate through the data in the result set and display it.
while (rs.next()) {

System.out.println(rs.getString(1) + " " + rs.getString(2));
}
}

// Handle any errors that may have occurred.
catch (Exception e) {
e.printStackTrace();
}

finally {
if (rs != null) try { rs.close(); } catch(Exception e) {}
if (cstmt != null) try { cstmt.close(); } catch(Exception e) {}
if (con != null) try { con.close(); } catch(Exception e) {}
}
}
}

Merci pour votre aide