blackberry: adding checkboxes in a list - blackberry

Question

I have fetched contact list successfully. But I am not able to add check boxes with that list. I have made separate program from checkbox and its working. but not with the contact list. Can anybody tell me here where should I add checkboxes? Here is the code:
public final class ContactsScreen extends MainScreen implements ListFieldCallback {
private ListField listField;
private ContactList blackBerryContactList;
private Vector blackBerryContacts;
public ContactsScreen(){
CheckboxField checkBox1 = new CheckboxField();
setTitle(new LabelField( "Contacts", LabelField.ELLIPSIS | LabelField.USE_ALL_WIDTH ));
listField = new ListField();
listField.setCallback(this);
add(listField);
add(new RichTextField("Size" +(listField)));
reloadContactList();
}
private boolean reloadContactList() {
try {
blackBerryContactList = (ContactList)PIM.getInstance().openPIMList(PIM.CONTACT_LIST, PIM.READ_ONLY);
Enumeration allContacts = blackBerryContactList.items();
blackBerryContacts = enumToVector(allContacts);
listField.setSize(blackBerryContacts.size());
return true;
}
catch(PIMException e){
return false;
}
}
private Vector enumToVector(Enumeration contactEnum) {
Vector v = new Vector();
if (contactEnum == null)
return v;
while (contactEnum.hasMoreElements()) {
v.addElement(contactEnum.nextElement());
}
return v;
}
public void drawListRow(ListField fieldVar, Graphics graphics, int index, int y, int width){
if ( listField == fieldVar && index < blackBerryContacts.size())
{
add(new RichTextField(blackBerryContacts.size()));
BlackBerryContact item = (BlackBerryContact)blackBerryContacts.elementAt(index);
String displayName = getDisplayName(item);
graphics.drawText(displayName, 0, y, 0, width);
}
}
public Object get(ListField fieldVar, int index)
{
if (listField == fieldVar) {
return blackBerryContacts.elementAt(index);
}
return null;
}
public int getPreferredWidth(ListField fieldVar ) {
return Display.getWidth();
}
public int indexOfList(ListField fieldVar, String prefix, int start)
{
return -1; // not implemented
}
public static String getDisplayName(Contact contact) {
if (contact == null) {
return null; }
String displayName = null;
// First, see if there is a meaningful name set for the contact.
if (contact.countValues(Contact.NAME) > 0) {
final String[] name = contact.getStringArray(Contact.NAME, 0);
final String firstName = name[Contact.NAME_GIVEN];
final String lastName = name[Contact.NAME_FAMILY];
if (firstName != null && lastName != null) {
displayName = firstName + " " + lastName;
} else if (firstName != null) {
displayName = firstName;
} else if (lastName != null) {
displayName = lastName;
}
} return displayName;
}
}

Answer 1

ListField is not designed for this. Its list item is not a Manager, so you can't add any child fields to it. In other words this is not possible with ListField on BB. ListField is a way to represent on UI a long list without eating too much RAM (since in this case there is the only UI object - the ListField).
If your list is not too long (10 - 20 items) then consider using VerticalFieldManager instead of ListField. If list is long && you really need check boxes on it then consider using VerticalFieldManager + list pagination.