public static Integer[] getSharedUserIds(Item x, Item y) {
List<Integer> sharedUsers = new ArrayList<Integer>();
for (Rating r : x.getAllRatings()) {
// same user rated the item
if (y.getUserRating(r.getUserId()) != null) {
sharedUsers.add(r.getUserId());
}
}
return sharedUsers.toArray(new Integer[sharedUsers.size()]);
}
public Item(Integer id, String name, List<Rating> ratings) {
this.id = id;
this.name = name;
// load ratings into userId -> rating map.
ratingsByUserId = new HashMap<Integer, Rating>(ratings.size());
for (Rating r : ratings) {
ratingsByUserId.put(r.getUserId(), r);
}
}
/**
* Updates existing user rating or adds a new user rating for this item.
*
* @param r rating to add.
*/
public void addUserRating(Rating r) {
ratingsByUserId.put(r.getUserId(), r);
}