Trying to save array database

Question

I'm having difficulty saving my database and restoring for my array. I think the problem is that I used the ArrayList class rather than making my own. I know how to do a save if I make the array, but I can't seem to get it to work with the ArrayList class. I'm required to use the ArrayList class for my array rather than make my own, but I also need to have the ability to save. If anyone has the time, I'd really appreciate some input
Thanks
MAIN:
import java.util.*;
import javax.swing.*;
public class SquiresProject1 {
     public static void main(String[] args) throws Exception {
          int menuCode, add, delete;
          boolean search = false, repeat = false, done = false;
          String saveChoice;
          //new record meant for an array of 10 in CreativeResources
         ArrayList customer = new ArrayList(10);
          SquiresSave save = new SquiresSave();
         //open file with saved data
          //control loop - enter 0 when finished
         while (!done) {
               //prompt, get menuCode, parse into an integer
              menuCode = Integer.parseInt(JOptionPane.showInputDialog(null,
                   "1. Add customer"
                        + "\n2. Delete customer"
                             + "\n3. Search for a customer"
                                  + "\n4. List all customers"
                                       + "\n5. Save your progress"
                                            + "\n6. Restore from last save point"
                                                 + "\n **Enter 0 to end program**"
                                                      + "\n Please enter a choice: "));
               switch (menuCode) {
                    //end loop and program
                    case 0:
                         done = true;
                         break;
                    //search for duplicates and add customer
                    case 1:
                         String customerToAdd = JOptionPane.showInputDialog(null,
                              "Customer's name: ");
                         repeat = customer.contains(customerToAdd);
                         if (repeat == false){
                         customer.add(customerToAdd);
                         JOptionPane.showMessageDialog(null, customerToAdd + " was successfully added to the list");
                         else
                         JOptionPane.showMessageDialog(null, "Sorry, but " + customerToAdd + " is already in the list");
                                                  break;
                    //sort, search for and delete customer
                    case 2:
                         String customerToDelete = JOptionPane.showInputDialog(null,
                              "Customer to delete: ");
                         customer.remove(customerToDelete);
                         JOptionPane.showMessageDialog(null, customerToDelete + " was successfully removed");
                         break;
                    //sort, search for customer
                    case 3:
                    String customerToSearch = JOptionPane.showInputDialog(null,
                              "Customer to search for: ");
                         search = customer.contains(customerToSearch);
                         if (search == true){
                         JOptionPane.showMessageDialog(null, customerToSearch + " is in the database");
                         delete = JOptionPane.showConfirmDialog(null, "would you like to delete " + customerToSearch + "?", "Run Again Dialog",     JOptionPane.YES_NO_OPTION);
                              if (delete == JOptionPane.YES_OPTION){
                            customer.remove(customerToSearch);
                              JOptionPane.showMessageDialog(null, customerToSearch + " was successfully removed");
                         else
                         JOptionPane.showMessageDialog(null, "Sorry, but " + customerToSearch + " is not in the database");
                         break;
                    //sort, traverse and list array
                    case 4:
                              JOptionPane.showMessageDialog(null, customer.toArray());
                                                  break;
                    //sort, save progress
                    case 5:
                    save.saveData();
                                                  break;
                    //restore from last save
                    case 6:
                         save.restoreData();
                         break;
                    //invalid choice - ask for input again
                    default:
                         JOptionPane.showMessageDialog(null, "Bad input. Read the choices carefully!");
          //prompt to save data
          saveChoice = JOptionPane.showInputDialog(null,
               "Would you like to save your data? y/n?");
          if ((saveChoice.equalsIgnoreCase("y")) || (saveChoice.equalsIgnoreCase("yes"))) {
               save.saveData();
          else
               JOptionPane.showMessageDialog(null, "You chose not to save your data.\nData not saved!");
          //closing
          JOptionPane.showMessageDialog(null, "Program ending.  Have a nice day!");
}MY ATTEMPT AT A SAVE/RESTORE METHOD CLASS:
import java.io.*;
import java.util.*;
public class SquiresSave{
public static int DEFAULT_SIZE = 10;
private int countOfCustomers;
private String[] customers;
private int customerPosition;
     public SquiresSave(int maxCustomers) {
          customers = new String[maxCustomers];
          countOfCustomers = 0;
          customerPosition = 0;
     //constructor
     public SquiresSave() {
          customers = new String[DEFAULT_SIZE];
          countOfCustomers = 0;
          customerPosition = 0;
     public void saveData() {
          int writeCount = 0;
          try {
               //open database.txt and write array to it
               PrintWriter outputStream = new PrintWriter(new FileOutputStream("database.txt"));
               while (writeCount < (countOfCustomers)) {
                    outputStream.println(customers[writeCount]);
                    writeCount++;
               //close database.txt
               outputStream.close();
               System.out.println("Data saved to file: database.txt");
          //catches all IOException errors
          catch (IOException e) {
               System.out.println("Error writing to file database.txt.\nData not saved!");
////////////////////////////////////restores data///////////////////////////////////////
     public void restoreData() {
          try {
               //open database.txt
               BufferedReader inputStream = new BufferedReader(
                    new FileReader("database.txt"));
               String line = inputStream.readLine();
               countOfCustomers = 0;
               //read and assign lines to customers until customers is full or file is completely read
               while ((line != null) && (countOfCustomers < customers.length)) {
                    customers[countOfCustomers] = line;
                    countOfCustomers++;
                    line = inputStream.readLine();
               inputStream.close();
               System.out.println("Data restored from file database.txt");
          catch(FileNotFoundException e) {
               System.out.println("Error reading input file: database.txt.\nData not restored!");
          catch(IOException e) {
               System.out.println("Error reading data from database.txt.\nData not restored!");
}

Answer 1

Hi,
at first you have to pass the data to your save method and get it from your restore method. You can do that simply with a argument in the methods. See http://java.sun.com/docs/books/tutorial/java/javaOO/arguments.html.
In your example, you could use
                    //sort, save progress
                    case 5:
                         save.saveData(customer);
                         break;
                    //restore from last save
                    case 6:
                         save.restoreData(customer);
                         break;
...Then your save/restore methody could look like:
     public void saveData(ArrayList<String> customer) {
          try {
               //open database.txt and write array to it
               PrintWriter outputStream = new PrintWriter(new FileOutputStream("database.txt"));
               for (ListIterator i = customer. listIterator(); i.hasNext();) {
                    outputStream.println((String)i.next());
               //close database.txt
               outputStream.close();
               System.out.println("Data saved to file: database.txt");
          //catches all IOException errors
          catch (IOException e) {
               System.out.println("Error writing to file database.txt.\nData not saved!");
////////////////////////////////////restores data///////////////////////////////////////
     public void restoreData(ArrayList<String> customer) {
          try {
               //open database.txt
               BufferedReader inputStream = new BufferedReader(
                    new FileReader("database.txt"));
               String line = "";
                                    customer.clear();
               //read and assign lines to customers until customers is full or file is completely read
               while ((line = inputStream.readLine()) != null) {
                                       customer.add(line);
               inputStream.close();
               System.out.println("Data restored from file database.txt");
          catch(FileNotFoundException e) {
               System.out.println("Error reading input file: database.txt.\nData not restored!");
          catch(IOException e) {
               System.out.println("Error reading data from database.txt.\nData not restored!");
...And please deal with generics. See http://java.sun.com/docs/books/tutorial/extra/generics/index.html. Then you can declare the ArrayList better as ArraList<String>.
greetings
Axel
Edited by: Axel_Richter on Sep 22, 2007 8:48 AM