How to connect oracle zul file and java file

public  static String verifiCoord (Textbox log2,Textbox pd2) {
		//je linitialise pas car la methode appele est en static .
		String login = log2.getValue();
		String pwd = pd2.getValue();
	    ResultSet rs;
	    
	    	try { 

	    		String driverName = "oracle.jdbc.driver.OracleDriver";
	    		Class.forName(driverName);
	    		System.out.println("driver trouveeeeeeeee");
	    	} 
	    	catch (ClassNotFoundException e) 
	    	   { 
	    		System.out.println("Driver classe non trouveeeeeeeeeee");
	           }
	    	try{
	    		connect=DriverManager.getConnection("jdbc:oracle:thin:@dellprecision:1521:metuu","scott","azerty");
	    	}catch(SQLException e){
	    		System.out.println("Connection impossibleeeeeeeeee base de donnees" +e);
	    	}
	    	try{
	    		Statement s=connect.createStatement();
	    	    String sql="select login from usersesion where login ='";
	    	    sql+=login;
	    	    sql+="'";
	    	    sql+="and pwd='";
	    	    sql+=pwd;
	    	    sql+="'";
	    	    rs=s.executeQuery(sql);
       	    retourChaine = rs.getString(1);
	    s.close();
	    	}catch(SQLException s){
	    		System.out.println("erreur requete"+s.getMessage());
	    	}
System.out.println("valeur de ma chaine"+retourChaine);
		return retourChaine;
	}

<?page title="Authentification Utilisateur" ?>

  <window title="Authentification Utilisateur" width="300px" 
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:zk="http://www.zkoss.org/2005/zul"
        xsi:schemaLocation="http://www.zkoss.org/2005/zul 
        http://www.zkoss.org/2005/zul"
        id="auth_window" border="none">
      <zscript >
  <![CDATA[//@IMPORT
import course.Login;
import course.Entry;]]>
<![CDATA[//@DECLARATION
         Entry e = new Entry();
     Login l = new Login();
         ]]>
  </zscript>
    <grid>
  <rows>
<row><label value="Nom d'utilisateur"/></row>
<row><textbox id="username"></textbox></row>
<row> <label value="Mot de passe"/></row>
<row><textbox id="pwd"></textbox></row>
<row><button label="Se connecter" onClick="l.verifiCoord(username,pwd);"></button></row>
</rows>
</grid>
</window>

Driver classe non trouveeeeeeeeeee
Connection impossibleeeeeeeeee base de donneesjava.sql.SQLException: No suitable driver
23 avr. 2010 16:20:02 org.zkoss.zk.ui.impl.UiEngineImpl handleError:1130
GRAVE: >>java.lang.NullPointerException
>>	at course.Login.verifiCoord(Login.java:42)
>>	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)