import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class DBMethods {

private final static String DB_URL = "jdbc:mysql://localhost:3306/customer?";
private final static String DB_USER = "root";
private final static String DB_PASSWORD = "Spn16058!";

private static Connection con;

static {
   try {
         Class.forName("com.mysql.jdbc.Driver");
   } catch (ClassNotFoundException ex) {
         ex.printStackTrace();
   }
}

public static Connection getConnection() throws SQLException {
   if (con == null || con.isClosed()) {
         con = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
   }
   return con;
}

public static void closeConnection() throws SQLException {
   if(con != null) {
         con.close();
   }
}

public boolean addCustomer(Customer customer) {
   try {
         Connection con = getConnection();

         String sql = "INSERT INTO Customers (id, name, creditcard) VALUES(?,?,?)";
         PreparedStatement ps = con.prepareStatement(sql);
         ps.setInt(1, customer.getCustomerId());
         ps.setString(2, customer.getName());
         ps.setString(3, customer.getCreditCardNumber());
         ps.executeUpdate();
         return true;

   }catch (Exception e) {
         e.printStackTrace();
   }
   return false;
}

public boolean addRental(Rental rental, String name) {
   try {
         Connection con = getConnection();
         String sql = "INSERT INTO Rentals (name, title, price, rentalcode) VALUES(?,?,?,?)";
         PreparedStatement ps = con.prepareStatement(sql);
         ps.setString(1, name);
         ps.setString(2, rental.getTitle());
         ps.setDouble(3, rental.getPrice());
         ps.setString(4, rental.getRentalCode());
         ps.executeUpdate();
         return true;

   }catch (Exception e) {
         e.printStackTrace();
   }

   return false;
}

public boolean customerExists(String name) {
   try {
         Connection con = getConnection();
         String sql = "SELECT * FROM Customers where name=?";
         PreparedStatement ps = con.prepareStatement(sql);
         ps.setString(1, name);
         //ps.executeUpdate();
         ResultSet rs = ps.executeQuery();
         if(rs != null && rs.next()){
            return true;
         }
   }catch (Exception e) {
         e.printStackTrace();
   }
   return false;
}

public boolean customerIdExists(int id) {
   try {
         Connection con = getConnection();
         String sql = "SELECT * FROM Customers where id=?";
         PreparedStatement ps = con.prepareStatement(sql);
         ps.setInt(1, id);
         //ps.executeUpdate();
         ResultSet rs = ps.executeQuery();
         if(rs != null && rs.next()){
            return true;
         }
   }catch (Exception e) {
         e.printStackTrace();
   }
   return false;
}

public ArrayList<Customer> fetchAllCustomers(){
   ArrayList<Customer> lstCustomer = new ArrayList<>();
   try {
         Connection con = getConnection();
         String sql = "SELECT * FROM Customers";
         PreparedStatement ps = con.prepareStatement(sql);
         ResultSet rs = ps.executeQuery();
         while (rs.next()){
            String name = rs.getString("name");
            String card = rs.getString("creditcard");
            Customer customer = new Customer();
            customer.setName(name);
            customer.setCreditCardNumber(card);
            customer.setRentalList(fetchRentals(name));
            lstCustomer.add(customer);
         }
   }catch (Exception e) {
         e.printStackTrace();
   }
   return lstCustomer

Write a servlet that displays a 3x3 grid: at the beginning, the 9 c...