@Override
public List<Period> separate(Items items) {
final SimpleDateFormat byMonthFormat = new SimpleDateFormat("yyyy-MM");
final Map<String, Items> separatedItems = new TreeMap<String, Items>();
for (Item item : items) {
final String key = byMonthFormat.format(item.getDate());
if (!separatedItems.containsKey(key)) {
separatedItems.put(key, items.copyStructure());
}
separatedItems.get(key).add(item);
}
return toSortedList(separatedItems);
}
@Override
public Object retrieve(Item item, String propertyName) {
return item.getProperty(propertyName);
}