refactoring-ornek-1-adim-4.java

public List<Trip> getTripsByUser(User user) throws UserNotLoggedInException {
    User loggedUser = UserSession.getInstance().getLoggedUser();

    if(loggedUser == null){
        throw new UserNotLoggedInException();
    }

    return isFriend(user.getFriends(), loggedUser) ?
          TripDAO.findTripsByUser(user) : new ArrayList<Trip>();
}

private boolean isFriendOf(User user, User loggedUser){
    return user.getFriends().contains(loggedUser);
}