public void PutAnnouncement(int id, Announcement announcement)
 {
     announcement.id = id;
     if (!repository.Update(announcement))
     {
         throw new ArgumentNullException("Opps ! There is no announcement with id #" + id + "  !");
     }
 }
 public void Post(Announcement newAnnouncement)
 {
     if (newAnnouncement == null)
     {
         throw new ArgumentNullException("Opps ! Announcement object is null that was sended !");
     }
     newAnnouncement.id = _nextId++;
     announcements.Add(newAnnouncement);
 }
 public bool Update(Announcement updatedAnnouncement)
 {
     if (updatedAnnouncement == null)
     {
         throw new ArgumentNullException("Opps ! Announcement object is null that was sended !");
     }
     else
     {
         var announcement = this.Get(updatedAnnouncement.id);
         if (announcement.id == -1)
         {
             return false;
         }
         announcement.Title = updatedAnnouncement.Title;
         announcement.Content = updatedAnnouncement.Content;
         return true;
     }
 }
 public void PostAnnouncement(Announcement newAnnouncement)
 {
     repository.Post(newAnnouncement);
 }