}
public Interest getInterest(User user, Topic topic) {
Interest interest = null;
try {
SelectionCriteria topicCriteria = SelectionCriteria
.defineEqualCriteria("topic", topic);
Interests topicInterests = (Interests) getEntities(topicCriteria);
SelectionCriteria userCriteria = SelectionCriteria
.defineEqualCriteria("user", user);
Interests userInterests = (Interests) topicInterests
.getEntities(userCriteria);
if (userInterests.size() == 1) {
interest = (Interest) userInterests.first();