connectivity problem

i am facing error in Class.for name statement please help me correct it the error is ""java.lang.ClassNotFoundException: oracle.jdbc.OracleDriver"" i am using this with netbeans since i have gain connectivity still i am facing this error*

================================oracle connectivity program============================

import java.sql.*;
import java.util.*;

class Test
{
static
{
     try{
    Class.forName("oracle.jdbc.OracleDriver");
    }
      catch(Exception err)
    {
            System.out.println("error..........."+err);
    }
}
public static void main(String []args)
    {

try{
        Scanner s=new Scanner(System.in);
        System.out.println("enter ename");
        String ename=s.next();
        System.out.println("enter eid");
        String eid=s.next();
        Connection con=DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:XE","HR","HR");
        PreparedStatement st=con.prepareStatement("update t1 set ename=? where eid=?");
        st.setString(1,ename);
        st.setString(2,eid);
        st.executeUpdate();
System.out.println("record updated");

    }
catch(Exception err)
{
System.out.println(err);
}
    }

}