ComboBoxModel<UnitSystem> unitSystemModel = new DefaultComboBoxModel<>(new UnitSystem[]{
Metric, Statute, Nautic
});
unitSystemModel.setSelectedItem(r.getUnitSystemModel().getUnitSystem());
comboBoxUnitSystem.setModel(unitSystemModel);
comboBoxUnitSystem.setRenderer(new UnitSystemListCellRenderer());
comboBoxUnitSystem.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() != SELECTED)
return;
UnitSystem unitSystem = UnitSystem.class.cast(e.getItem());