Problemas com o metodo delete

/*
 * NewServlet.java
 *
 * Created on 28 de Abril de 2008, 00:20
 */

package controle;

import Bean.Cliente;
import Persistencia.ClienteDao;
import java.io.*;
import java.util.Iterator;

import javax.servlet.*;
import javax.servlet.http.*;

/**
 *
 * @author Thiago Meinel
 * @version
 */
public class NewServlet extends HttpServlet {
    
    /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        
     Cliente client = new Cliente();
     ClienteDao dao = new ClienteDao();
     
     dao.open();
  
     Iterator it = dao.apagar(client).iterator();

                           while(it.hasNext()){
                            Cliente cliente = (Cliente)it.next();
                           
                            out.print("<a href = Apagar?id=" + cliente.getId()+ ">Deletar</a><br>");
                            out.print("Nome:" + cliente.getNome()+"<br>");
                            out.print("Email: " + cliente.getEmail()+"<br>");
                            out.print("Endereco: " + cliente.getEndereco()+"<br>");
                            
                            
           }
                  
           
       
        out.close();
    }
    
    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Returns a short description of the servlet.
     */
    public String getServletInfo() {
        return "Short description";
    }
    // </editor-fold>
}

public List apagar(Cliente cli){
           List list = new ArrayList();    
        try{
            stmt = con.prepareStatement("SELECT * FROM CONTATOS");
           
            rs = stmt.executeQuery();
             
            while(rs.next()){
                
                Cliente cliente = new Cliente();
                cliente.setId(rs.getLong("id"));
                cliente.setNome(rs.getString("nome"));
                cliente.setEmail(rs.getString("email"));
                cliente.setEndereco(rs.getString("endereco"));
                list.add(cliente);
            }
                     
                              
        }catch(Exception e){
            e.getMessage();
        }
     return list;
    }
        
        public void deletar(Cliente cliente,PrintWriter out){
            try{
              stmt = con.prepareStatement("DELETE FROM CONTATOS WHERE ID = ?");
                stmt.setLong(1,cliente.getId());
                stmt.executeUpdate();
                
                out.print(cliente.getId());
            }catch(Exception e){
                e.getMessage();
            }
        }