/**
  *
  *
  *
  *
  *
  */
 public StubViewModel()
 {
     this.currentUser = null;
     isLogin          = false;
     DataModel.init();
     //在通讯录显示的(离线数据)
     this.groups  = new ObservableCollection <GroupViewModel>();
     this.friends = new ObservableCollection <FriendViewModel>();
     this.chats   = new ObservableCollection <ChatViewModel>();
 }
 /**
  * Log Out User
  */
 public bool logout()
 {
     if (!isLogin)
     {
         return(false);
     }
     this.isLogin     = false;
     this.currentUser = null;
     return(true);
 }