static JComboBox jcombobox(fS... items) {
  ret swing(func -> JComboBox { new JComboBox(items) });
}

static JComboBox jcombobox(Collection<S> items) {
  ret jcombobox(toStringArray(items));
}

static JComboBox jcombobox(Collection<S> items, S selectedItem) {
  ret setSelectedItem(selectedItem, jcombobox(items));
}