Windows phone 8 Telerik RadDataBoundListBox重置

如何重置或删除Telerik RadDataBoundListBox中的旧数据 Json解析和显示在RadDataBoundListBox中

RadDataBoundListBox每次加载旧数据，如果我点击按钮加载新数据，我想删除或重置旧数据，因为每次显示旧数据时

public void getMainData()
        {

            string mainUrlData = "http://www.mydomain.com/app.json";

            WebClient wc = new WebClient();
            wc.DownloadStringCompleted += wc_DownloadStringCompleted;
            wc.DownloadStringAsync(new Uri(mainUrlData));
           }


        void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
        {
            try
            {
                string result = e.Result.ToString();
                JsonConvert.PopulateObject(result, PopulateData);
                NewsList.ItemsSource = PopulateData;
            }
       }

---

有点晚了，希望这有帮助

使用MVVMLight

使用HttpClient：

    public async Task<ObservableCollection<T>> GetAll()
    {
        var client = new HttpClient();

        client.DefaultRequestHeaders.Accept.Add(MediaTypeWithQualityHeaderValue.Parse(jsonMediaType));
        //if (useToken)
        //client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", Token);

        var json = await client.GetStringAsync(String.Format("{0}{1}{2}", apiUrl, addressSuffix, apiKey)).ConfigureAwait(false);

        Debug.WriteLine(json);

        JObject o = JObject.Parse(json);

        Debug.WriteLine(o);

        return await Task.Factory.StartNew(() => JsonConvert.DeserializeObject<ObservableCollection<T>>(o[moduleName].ToString()));
    }

private ObservableCollection<Ticket> _myTickets;

    public ObservableCollection<Ticket> MyTickets
    {
        get
        {
            return _myTickets;
        }
        set
        {
            _myTickets = value;

            RaisePropertyChanged(() => MyTickets);
        }
    }

<telerikPrimitives:RadDataBoundListBox 
                x:Name="radDataBoundListBox"
                ItemsSource="{Binding TicketList}"
                ItemTemplate="{StaticResource ListBoxItemTemplate}"
                ItemContainerStyle="{StaticResource ItemContainerStyle}"
                SelectedItem="{Binding SelectedTicket, Mode=TwoWay}"
                HorizontalAlignment="Stretch"
                VerticalAlignment="Stretch"
                Height="750"
                ScrollViewer.VerticalScrollBarVisibility="Auto"
                UseOptimizedManipulationRouting="False"
                EmptyContent="Laden..."
                IsPullToRefreshEnabled="True">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="RefreshRequested">
                    <cmd:EventToCommand 
                        Command="{Binding RefreshRequested}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </telerikPrimitives:RadDataBoundListBox>

    private RelayCommand _refreshCommand;

    public RelayCommand RefreshRequested
    {
        get
        {
            return _refreshCommand
                ?? (_refreshCommand = new RelayCommand(
                                      () =>
                                      {
                                          ExecuteRefreshCommand();
                                      }));
        }
    }

public async void ExecuteRefreshCommand()
    {
            var tickets = await _dataService.GetAll();

            if (tickets != null)
            {
                _ticketList.Clear();

                foreach (var ticket in tickets)
                {
                    _ticketList.Add(ticket);
                    Debug.WriteLine(ticket.name);
                }

                Messenger.Default.Send(new HandleViewMessage() { StopPullToRefresh = true });

                RaisePropertyChanged(() => TicketList);
            }
    }