Duvida no metodo ChoiceGroup

public class Teste extends MIDlet{
    private Display display;
    private Form form;
    private ChoiceGroup c_grupo;
    private Command submit;

    protected void destroyApp(boolean unconditional) throws MIDletStateChangeException {

    }

    protected void pauseApp() {

    }

    protected void startApp() throws MIDletStateChangeException {
       c_grupo = new ChoiceGroup("Option :", ChoiceGroup.POPUP);
       c_grupo.append("Masculino", null);
       c_grupo.append("Femenino",null);

       form = new Form("Choise one this options.");
       form.append(c_grupo);
       display = Display.getDisplay(this);
       display.setCurrent(form);

       submit = new Command("Submit", Command.OK,0);
       form.addCommand(submit);
       form.setCommandListener((CommandListener) this);
       
    }

}