sclass ConceptsComboBox<A extends Concept> extends JComboBox<A> {

  Concepts concepts;

  Class<A> conceptClass;

  AWTOnConceptChanges updater;

  settable bool allowNull;

  settable IPred<A> itemFilter;

  *(Concepts *concepts, Class<A> *conceptClass) {

    updateItems();

    updater = new AWTOnConceptChanges(concepts, this, l0 updateItems);

    updater.install();

  }

  void updateItems {

    var l = sortTheList(filterTheList(freshList()));

    if (allowNull) l = nullPlus(l);

    setComboBoxItems_notifyListeners(this, l);

  }

  swappable Cl<A> freshList() {

    ret main list(concepts, conceptClass);

  }

  L<A> filterTheList(Cl<A> l) {

    ret itemFilter == null ? asList(l) : filter(itemFilter, l);

  }

  swappable L<A> sortTheList(L<A> l) {

    ret sortConceptsByID(l);

  }

  selfType sorter(IF1<L<A>> sorter) { sortTheList = sorter; this; }

  A get() { ret getSelectedItem_typed(this); }

  void select(long conceptID) {

    main setSelectedItem(this, getConcept(concepts, conceptClass, conceptID));

  }

}