Memanipulasi data dalam record store, pada JAVA (J2ME)

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;

public class DemoRMS extends MIDlet
  implements CommandListener {
   
  private Display display;
  private Form form;
  private RecordStore rs;
  private RecordEnumeration re;
  private ChoiceGroup choicegroup;
  private Alert alert;
  private List list;
   
  //untuk proses entri data
  private Form entri;
  private TextField tfNama, tfNoTelp;
   
  private final Command cmdKeluar =
    new Command("Keluar", Command.EXIT, 1);
  private final Command cmdPilih =
    new Command("Pilih", Command.OK, 1);
  private final Command cmdSimpan =
    new Command("Simpan", Command.SCREEN, 1);
  private final Command cmdHapus =
    new Command("Hapus", Command.SCREEN, 1);
  private final Command cmdKembali =
    new Command("Kembali", Command.BACK, 1);
 
  public DemoRMS() {
    display = Display.getDisplay(this);
     
    alert = new Alert(null);
    alert.setTimeout(Alert.FOREVER);
       
    list = new List(null, Choice.IMPLICIT);
      
    rs = null;
    // membuat atau membuka record store
    try {
      rs = RecordStore.openRecordStore("contohDB", true);
    } catch (RecordStoreException rse) {
      alert.setString("Record store tidak dapat dibuka. " +
                      "Aplikasi akan dihetikan");
      alert.setType(AlertType.ERROR);
      display.setCurrent(alert, null);
      System.exit(1);
    }
  }
   
  public void startApp() {
    form = new Form("Demo RMS");
        
    choicegroup = new ChoiceGroup("Menu:", Choice.EXCLUSIVE);
    choicegroup.append("Tambah Record", null);
    choicegroup.append("Daftar Record", null);
        
    form.append(choicegroup);
    form.addCommand(cmdKeluar);
    form.addCommand(cmdPilih);
    form.setCommandListener(this);
    display.setCurrent(form);
  }  
   
  public void pauseApp() {
  }
   
  public void destroyApp(boolean unconditional) {
  }
   
  public void commandAction(Command c, Displayable s) {
    if (c == cmdKeluar) {
      destroyApp(false);
      notifyDestroyed();
    } else if (c == cmdPilih) {
      switch (choicegroup.getSelectedIndex()) {
        case 0: {
          entriData();
          break;
        }
        case 1: {
          lihatRecord();
          break;
        }
      }
    } else if (c == cmdKembali) {
      display.setCurrent(form);
    } else if (c == cmdSimpan) {
      alert.setType(AlertType.INFO);
      if (!tfNama.equals("") && !tfNoTelp.equals("")) {
        tambahRecord(tfNama.getString(), tfNoTelp.getString());
        alert.setString("Data baru telah berhasil disimpan");               
        display.setCurrent(alert, form);
      } else {
        alert.setString("Data NAMA dan NO. TELP " +
                        "tidak boleh kosong");               
        display.setCurrent(alert, entri);
      }           
    } else if (c == cmdHapus) {
      int pos =
        list.getString(list.getSelectedIndex()).indexOf(" [");
      String nama = list.getString(
       list.getSelectedIndex()).substring(0, pos);
       hapusRecord(nama);
    }
  }
   
  public void tambahRecord(String nama, String noTelp) {
    byte[] temp = null;
    try {
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      DataOutputStream dos = new DataOutputStream(baos);
      dos.writeUTF(nama);
      dos.writeUTF(noTelp);
      temp = baos.toByteArray();
    } catch (IOException ioe) {
      ioe.printStackTrace();
    }
    try {
      rs.addRecord(temp, 0, temp.length);
    } catch (RecordStoreNotOpenException rsnoe) {
      rsnoe.printStackTrace();
    } catch (RecordStoreException rse) {
      rse.printStackTrace();
    }
  }
   
  public void lihatRecord() {
    byte[] temp = null;
    list.setTitle("Daftar Record");
    list.deleteAll();
    try {           
      re = rs.enumerateRecords(null, null, false);
      while (re.hasNextElement()) {
        int i = re.nextRecordId();               
        temp = rs.getRecord(i);
        ByteArrayInputStream bais =
          new ByteArrayInputStream(temp);
        DataInputStream dis = new DataInputStream(bais);
        try {
          String nama = dis.readUTF();
          String noTelp = dis.readUTF();
          list.append(nama + " [" + noTelp + "]", null);                   
        } catch (IOException ioe) {
          ioe.printStackTrace();
        }
      }
      list.addCommand(cmdKembali);
      list.addCommand(cmdHapus);
      list.setCommandListener(this);
      display.setCurrent(list);
    } catch (InvalidRecordIDException invID) {
      invID.printStackTrace();
    } catch (RecordStoreNotOpenException rsnoe) {
      rsnoe.printStackTrace();
    } catch (RecordStoreException rse) {
      rse.printStackTrace();
    }
      
  }
   
  public void hapusRecord(String nama) {
    byte[] temp = null;
    try {
      re = rs.enumerateRecords(null, null, false);
      while (re.hasNextElement()) {
        int i = re.nextRecordId();
        temp = rs.getRecord(i);
        ByteArrayInputStream bais =
          new ByteArrayInputStream(temp);
        DataInputStream dis = new DataInputStream(bais);
        try {
          String vNama = dis.readUTF();
          if (vNama.equals(nama)) {
            rs.deleteRecord(i);
            break;
          }                   
        } catch (IOException ioe) {
          ioe.printStackTrace();
        }
      }
      re.rebuild();
      lihatRecord();
    } catch (RecordStoreNotOpenException rsnoe) {
      rsnoe.printStackTrace();
    } catch (RecordStoreException rse) {
      rse.printStackTrace();
    }
  }
       
  public Form entriData() {
    entri = new Form("Entri Data");
    tfNama = new TextField("Nama:", null, 25, TextField.ANY);
    tfNoTelp = new TextField("No. Telepon:", null, 15,
                              TextField.PHONENUMBER);
    entri.append(tfNama);
    entri.append(tfNoTelp);
    entri.addCommand(cmdSimpan);
    entri.addCommand(cmdKembali);
    entri.setCommandListener(this);
    display.setCurrent(entri);
    return entri;
  }
}