RecordStore, how to?

Question

I'm having trouble saving settings and stuff for my program. I tried using the class that Jimm (ICQ client) uses until I've learned more. It seems really nice, also works great, except that values aren't saved (or loaded!) sometimes.
I have no idea what might be wrong and there's TONS of code so posting won't be a good idea right now, I'm afraid.
Therefore, does anyone have a nice guide or anything on how to use recordstore? I'd like it to work like the windows registry, for instance, in other words, every entry has a name and a value. Recordstores doesn't appear to work like that, or do they?

Answer 1

Yup, that did help some, thanks.
However, I can't get my new code to work properly, and actually I can't figure out if the error is in load(), save() or both...
Anyway, it doesn't save/load properly.
If I try to store the int 1, the int 2, and the string "3" in that order, the result will come out 1, 1, and <empty string> when I load it later on.
"Some" code, I'd be very thankful for some helpful ideas.
import javax.microedition.lcdui.*;
import java.io.*;
import javax.microedition.io.*;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;
public class Options implements CommandListener
     public static String sCurrencyList[] = {"Euro, EUR", "USA, USD", "Great Britain, GBP", "Schweiz, CHF", "Denmark, DKK", "Norway, NOK", "Iceland, ISK", "Japan, JPY", "Canada, CAD", "Australia, AUD", "Cyprus, CYP", "Hong kong, HKD", "New Zeeland, NZD", "Singapore, SGD", "S. Africa, ZAR", "Thailand, THB", "Czech Rep., CZK", "Sweden, SEK"};
     public Form optionsForm;
     private Command saveCommand, backCommand;
     private TextField tExchangeRate;
     private ChoiceGroup cgMyCurrency;
     private ChoiceGroup cgForeignCurrency;
     public int MY_CURRENCY = 0;
     public int FOREIGN_CURRENCY = 1;
     public String EXCHANGERATE;
     // Constructor
     public Options()
          try
               RecordStore rs = RecordStore.openRecordStore("opt", true);
               if (rs.getNextRecordID() == 1)
                    System.out.println("DB not found, setting up...");
                    rs.addRecord(null,0,0); // ID 1 = my currency (int)
                    rs.addRecord(null,0,0); // ID 2 = foreign currency (int)
                    rs.addRecord(null,0,0); // ID 3 = exchange rate (string)
                    byte[] buf;
                    ByteArrayOutputStream baos = new ByteArrayOutputStream();
                    DataOutputStream dos = new DataOutputStream(baos);
                    dos.writeInt(17);
                    buf = baos.toByteArray();
                    rs.setRecord(1, buf, 0, buf.length);
                    dos.writeInt(1);
                    buf = baos.toByteArray();
                    rs.setRecord(2, buf, 0, buf.length);
                    dos.writeUTF("7.35");
                    buf = baos.toByteArray();
                    rs.setRecord(3, buf, 0, buf.length);
                    // Set default options, now that the record store has been created
                    this.MY_CURRENCY = 17;
                    this.FOREIGN_CURRENCY = 1;
                    this.EXCHANGERATE = "7.35";
               else // Database already existed, read the info
                    System.out.println("DB found, reading info");
                    byte [] buf;
                    ByteArrayInputStream bas;
                    DataInputStream dis;
                    buf = rs.getRecord(1);
                    bas = new ByteArrayInputStream(buf);
                    dis = new DataInputStream(bas);
                    this.MY_CURRENCY = dis.readInt();
                    System.out.println ("Read MY_CURRENCY: " + this.MY_CURRENCY);
                    buf = rs.getRecord(2);
                    bas = new ByteArrayInputStream(buf);
                    dis = new DataInputStream(bas);
                    this.FOREIGN_CURRENCY = dis.readInt();
                    System.out.println ("Read FOREIGN_CURRENCY: " + this.FOREIGN_CURRENCY);
                    buf = rs.getRecord(3);
                    bas = new ByteArrayInputStream(buf);
                    dis = new DataInputStream(bas);
                    this.EXCHANGERATE = dis.readUTF();
                    System.out.println ("Read EXCHANGERATE: " + this.EXCHANGERATE);
               rs.closeRecordStore();
          catch (Exception e)
               System.out.println("An Exception occurred while reading/creating the DB." + e.toString());
               // Ignore, for now...
     public void show()
          System.out.println("show() invoked");
          saveCommand = new Command("Save", Command.SCREEN, 1);
          backCommand = new Command("Back", Command.BACK, 1);
          optionsForm = new Form("Options");
          Image[] imageArray = null;
          cgMyCurrency = new ChoiceGroup("My currency", Choice.POPUP, sCurrencyList, imageArray);
          cgForeignCurrency = new ChoiceGroup("Foreign currency", Choice.POPUP, sCurrencyList, imageArray);
          tExchangeRate = new TextField("Exchange rate", "", 15, TextField.DECIMAL);
          cgMyCurrency.setSelectedIndex(this.MY_CURRENCY, true);
          cgForeignCurrency.setSelectedIndex(this.FOREIGN_CURRENCY, true);
          tExchangeRate.setString(this.EXCHANGERATE);          
          optionsForm.append(cgMyCurrency);
          optionsForm.append(cgForeignCurrency);
          optionsForm.append(tExchangeRate);
          optionsForm.addCommand(backCommand);
          optionsForm.addCommand(saveCommand);
          optionsForm.setCommandListener(this);
          OptMain.display.setCurrent(optionsForm);
     public void save()
          System.out.println("save() invoked");
          try
               this.MY_CURRENCY = cgMyCurrency.getSelectedIndex();
               this.FOREIGN_CURRENCY = cgForeignCurrency.getSelectedIndex();
               this.EXCHANGERATE = tExchangeRate.getString();
               RecordStore rs = RecordStore.openRecordStore("opt", false);
               byte [] buf;
               ByteArrayOutputStream bas;
               DataOutputStream dos;
               bas = new ByteArrayOutputStream();
               dos = new DataOutputStream(bas);
               dos.writeInt(this.MY_CURRENCY);
               buf = bas.toByteArray();
               rs.setRecord(1, buf, 0, buf.length);
               System.out.println ("Wrote MY_CURRENCY: " + this.MY_CURRENCY);
               dos.writeInt(this.FOREIGN_CURRENCY);
               buf = bas.toByteArray();
               rs.setRecord(2, buf, 0, buf.length);
               System.out.println ("Wrote FOREIGN_CURRENCY: " + this.FOREIGN_CURRENCY);
               dos.writeUTF(this.EXCHANGERATE);
               buf = bas.toByteArray();
               rs.setRecord(3, buf, 0, buf.length);
               System.out.println ("Wrote EXCHANGERATE: " + this.EXCHANGERATE);
               rs.closeRecordStore();
          catch (Exception e)
               System.out.println("An Exception occured in save(): " + e.toString());
     public void commandAction (Command c, Displayable d)
          if (c == saveCommand)
               System.out.println("Received saveCommand");
               this.save();
               OptMain.display.setCurrent(OptMain.mainMenu);
          else if (c == backCommand)
               System.out.println("Received backCommand");
               OptMain.display.setCurrent(OptMain.mainMenu);
}I'm guessing there's a better/easier/prettier way to read and write data, no?