Menempatkan beberapa objek ChoiceGroup dalam satu form, pada JAVA (J2ME)

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class DemoChoiceGroup extends MIDlet
  implements CommandListener {
   
  private Display display;
  private Form form;
  private TextField nama;
  private ChoiceGroup jenisKelamin, hobi;
   
  private Command cmdKeluar, cmdTampilkan;
   
  public DemoChoiceGroup() {
    display = Display.getDisplay(this);
       
    form = new Form("Demo ChoiceGroup");
      
    cmdKeluar = new Command("Keluar", Command.EXIT, 1);
    form.addCommand(cmdKeluar);
       
    cmdTampilkan = new Command("Tampilkan", Command.SCREEN, 1);
    form.addCommand(cmdTampilkan);
      
    form.setCommandListener(this);
  }
   
  public void startApp() {
    nama = new TextField("Nama", null, 25, TextField.ANY);
    form.append(nama);
       
    String[] gender = {"Laki-laki","Perempuan"};
    jenisKelamin = new ChoiceGroup("Jenis Kelamin",
                       Choice.EXCLUSIVE, gender, null);
    form.append(jenisKelamin);
       
    String[] hobbies = {"Membaca", "Memancing",
                        "Berolahraga", "Bersepeda"};
    hobi = new ChoiceGroup("Hobi", Choice.MULTIPLE,
                        hobbies, null);
    form.append(hobi);
       
    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 {
      Form newForm = new Form("Hasil");
          
      StringItem siNama = new StringItem("Nama:\n",
                              nama.getString(), Item.PLAIN);
      newForm.append(siNama);
           
      StringItem siJenisKelamin =
        new StringItem("Jenis kelamin:\n",              
        jenisKelamin.getString(jenisKelamin.getSelectedIndex()),
        Item.PLAIN);
      newForm.append(siJenisKelamin);
           
      StringBuffer sb = new StringBuffer();
      for (int i=0; i<hobi.size(); i++) {
        if (hobi.isSelected(i)) {
          sb.append("- " + hobi.getString(i) + "\n");
        }
      }

      StringItem siHobi = new StringItem("Hobi:\n",
                                sb.toString(), Item.PLAIN);
      newForm.append(siHobi);
           
      display.setCurrent(newForm);
    }
  }
}