Windows Phone 7.1アプリケーションのBing Mapsを使用して 'GeoCodeService'からの応答でコールバック中にNull参照例外が発生する

Question

私は、2つの異なる場所を検索し、それらの間のルートを表示するためにマップを表示する必要がある2つの場所と方向も含まれます。 "GeoCodeService"に場所のリクエストを送信するために使用する必要があるjson webserviceからTOとFROMのアドレス行を取得しています。

上記を達成するには、私はBing Maps - 「GeoCodeService」、「GeoRouteService」を使用し、次のコードを試しています。アプリケーションを実行している間、私はNullReferenceExceptionを取得していますが、GeoCodeServiceからのcallBack応答を取得しています。

私はWindows Phoneアプリケーションの開発において全く新しいので、完全なMVVMパターンを使用していません。しかし、私はJson Webserviceからデータを取得できましたが、GeoCodeServiceから結果を取得してマップにバインドすることができませんでした。

次

は私のXAMLコードである：以下

<controls:PivotItem Header="Map"> 
    <StackPanel Orientation="Vertical"> 
     <maps:Map x:Name="bingMap" 
        Center="50.851041,4.361572" 
        ZoomLevel="10" 
        CredentialsProvider="{StaticResource MapCredentials}"> 
      <maps:MapPolyline Locations="{Binding RoutePoints, Converter={StaticResource locationConverter}}" 
        Stroke="#FF0000FF" 
        StrokeThickness="5" /> 
      <maps:Pushpin Location="{Binding StartPoint, Converter={StaticResource locationConverter}}" 
        Content="Start" /> 
      <maps:Pushpin Location="{Binding EndPoint, Converter={StaticResource locationConverter}}" 
        Content="End" /> 
     </maps:Map> 
     <StackPanel Orientation="Horizontal" 
        VerticalAlignment="Bottom"> 
      <Button Margin="80,0,0,0" 
        x:Name="btnputodo" 
        Click="btnputodo_Click" 
        HorizontalAlignment="Left" 
        FontFamily="Verdana" 
        FontSize="18" 
        VerticalAlignment="Bottom" 
        BorderBrush="Transparent" 
        Height="60" 
        Content="Pu to Do" 
        Width="150" 
        Background="White" 
        Foreground="Black"/> 
      <Button x:Name="btnmyloctopu" 
        Click="btnmyloctopu_Click" 
        HorizontalAlignment="Left" 
        FontFamily="Verdana" 
        FontSize="18" 
        VerticalAlignment="Bottom" 
        BorderBrush="Transparent" 
        Height="60" 
        Content="Loc to Pu" 
        Width="150" 
        Background="White" 
        Foreground="Black"/> 
     </StackPanel> 
    </StackPanel> 
</controls:PivotItem> 
<controls:PivotItem Header="Directions"> 
    <ListBox ItemsSource="{Binding Itinerary, Converter={StaticResource itineraryConverter}}" 
      Grid.RowSpan="2" 
      ItemTemplate="{StaticResource ItineraryItemComplete}" /> 
</controls:PivotItem> 

である私のxaml.csコード（コードビハインド）：

private Location toLocation; 

private Location fromLocation; 

private Address from; 
public Address From 
{ 
    get { return from; } 
    set 
    { 
     from = value; 
     Change("From"); 
    } 
} 

private Address to; 
public Address To 
{ 
    get { return to; } 
    set 
    { 
     to = value; 
     Change("To"); 
    } 
} 
private Location startPoint; 
public Location StartPoint 
{ 
    get { return startPoint; } 
    set 
    { 
     startPoint = value; 
     Change("StartPoint"); 
    } 
} 

private Location endPoint; 
public Location EndPoint 
{ 
    get { return endPoint; } 
    set 
    { 
     endPoint = value; 
     Change("EndPoint"); 
    } 
} 

private ObservableCollection<Location> routePoints; 
public ObservableCollection<Location> RoutePoints 
{ 
    get { return routePoints; } 
    set 
    { 
     routePoints = value; 
     Change("RoutePoints"); 
    } 
} 

private ObservableCollection<ItineraryItem> itinerary; 
public ObservableCollection<ItineraryItem> Itinerary 
{ 
    get 
    { 
     return itinerary; 
    } 
    set 
    { 
     itinerary = value; 
     Change("Itinerary"); 
    } 
} 
public event PropertyChangedEventHandler PropertyChanged; 

private void Change(string property) 
{ 
    if (PropertyChanged != null) 
     PropertyChanged(this, new PropertyChangedEventArgs(property)); 
} 

public event EventHandler RouteResolved; 

private void RaiseRouteResolved() 
{ 
    if (RouteResolved != null) 
     RouteResolved(this, EventArgs.Empty); 
} 

private void btnputodo_Click(object sender, RoutedEventArgs e) 
{ 

    foreach (var dictionary in pickdrops) 
    { 
     if (dictionary.Key == "pickups") 
     { 
      locate = dictionary.Value; 
      this.From = new Address(); 
      this.From.AddressLine = locate; 
      this.From.Locality = this.From.AdminDistrict = this.From.CountryRegion = this.From.District = this.From.PostalCode = this.From.PostalTown = string.Empty; 
      ResolveRoute(); 

     } 
     if (dictionary.Key == "drops") 
     { 
      locate = dictionary.Value; 
      this.To= new Address(); 
      this.To.AddressLine = locate; 
      this.To.Locality = this.To.AdminDistrict = this.To.CountryRegion = this.To.District = this.To.PostalCode = this.To.PostalTown = string.Empty; 
      ResolveRoute1(); 

     } 
    } 
} 


public void ResolveRoute() 
{ 
    GetGeoLocation(From, (l) => fromLocation = l); 

} 

public void ResolveRoute1() 
{ 
    GetGeoLocation1(To, (l) => toLocation = l); 
} 

private void GetGeoLocation1(Address address, Action<Utils.WP7.Bing.BingGeo.GeocodeLocation> callBack) 
{ 
    var geoRequest = new GeocodeRequest(); 
    geoRequest.Credentials = new Credentials(); 
    geoRequest.Credentials.ApplicationId = App.BingApiKey; 
    geoRequest.Address = address; 

     var geoClient = new GeocodeServiceClient("BasicHttpBinding_IGeocodeService"); 
    geoClient.GeocodeCompleted += (s, e) => 
    { 
     string statusCode = e.Result.ResponseSummary.StatusCode.ToString(); 
     string ss = e.Result.Results == null ? "EMPTY" : "OK"; 
     if (e.Result.Results != null && e.Result.Results.Count > 0) 
     { 
      string dd = e.Result.Results[0].Locations[0].Latitude.ToString(); 
     } 

     // Am getting Exception at the below statement --> 
     callBack(e.Result.Results.FirstOrDefault().Locations.FirstOrDefault()); 
     // <--- 

     LocationLoaded(); 
    }; 
    geoClient.GeocodeAsync(geoRequest); 
} 

private void GetGeoLocation(Address address, Action<Utils.WP7.Bing.BingGeo.GeocodeLocation> callBack) 
{ 
    var geoRequest = new GeocodeRequest(); 
    geoRequest.Credentials = new Credentials(); 
    geoRequest.Credentials.ApplicationId = App.BingApiKey; 
    geoRequest.Address = address; 


    var geoClient = new GeocodeServiceClient("BasicHttpBinding_IGeocodeService"); 
    geoClient.GeocodeCompleted += (s, e) => 
    { 
     callBack(e.Result.Results.FirstOrDefault().Locations.FirstOrDefault()); 
     LocationLoaded(); 
    }; 
    geoClient.GeocodeAsync(geoRequest); 
} 


private void LocationLoaded() 
{ 
    if (fromLocation != null && toLocation != null) 
    { 
     var fromWaypoint = new Waypoint(); 
     fromWaypoint.Description = "From"; 
     fromWaypoint.Location = new Microsoft.Phone.Controls.Maps.Platform.Location(); 
     fromWaypoint.Location.Altitude = fromLocation.Altitude; 
     fromWaypoint.Location.Latitude = fromLocation.Latitude; 
     fromWaypoint.Location.Longitude = fromLocation.Longitude; 

     var toWaypoint = new Waypoint(); 
     toWaypoint.Description = "To"; 
     toWaypoint.Location = new Microsoft.Phone.Controls.Maps.Platform.Location(); 
     toWaypoint.Location.Altitude = toLocation.Altitude; 
     toWaypoint.Location.Latitude = toLocation.Latitude; 
     toWaypoint.Location.Longitude = toLocation.Longitude; 

     var routeRequest = new RouteRequest(); 
     routeRequest.Credentials = new Microsoft.Phone.Controls.Maps.Credentials(); 
     routeRequest.Credentials.ApplicationId = App.BingApiKey; 
     routeRequest.Waypoints = new System.Collections.ObjectModel.ObservableCollection<Waypoint>(); 
     routeRequest.Waypoints.Add(fromWaypoint); 
     routeRequest.Waypoints.Add(toWaypoint); 
     routeRequest.Options = new RouteOptions(); 
     routeRequest.Options.RoutePathType = RoutePathType.Points; 
     routeRequest.UserProfile = new Utils.WP7.Bing.BingRoute.UserProfile(); 
     routeRequest.UserProfile.DistanceUnit = Utils.WP7.Bing.BingRoute.DistanceUnit.Kilometer; 

     var routeClient = new RouteServiceClient("BasicHttpBinding_IRouteService"); 
     routeClient.CalculateRouteCompleted += new EventHandler<CalculateRouteCompletedEventArgs>(OnRouteComplete); 
     routeClient.CalculateRouteAsync(routeRequest); 
    } 
} 

private void OnRouteComplete(object sender, CalculateRouteCompletedEventArgs e) 
{ 
    if (e.Result != null && e.Result.Result != null && e.Result.Result.Legs != null & e.Result.Result.Legs.Any()) 
    { 
     var result = e.Result.Result; 
     var legs = result.Legs.FirstOrDefault(); 

     StartPoint = legs.ActualStart; 
     EndPoint = legs.ActualEnd; 
     RoutePoints = result.RoutePath.Points; 
     Itinerary = legs.Itinerary; 


    } 
} 

Answer 1

私はあなたの問題はあなたがどのように関係していると思いますあなたの要求から結果データを抽出する。

if (e.Result.Results != null && e.Result.Results.Count > 0) 
    (... some logic here ...) 

しかし、私はそれがそうする方が良いと思う：

if(e.Error == null) 
    // HERE YOU'D WANT TO MANAGE A REQUEST EXCEPTION 
    // (FOR EXAMPLE AN UNPREDICTABLE PROBLEM OF THE BING WEB SERVICE!) 
    // e.Error is an Exception class 
else 
{ 
    // Get the first result received: 
    var geoResult = (from r in e.Result.Results 
        orderby (int)r.Confidence ascending // USE THIS CLAUSE TO SORT THE RESULT BY CONFIDENCE, OTHERWISE REMOVE IT! 
        select r).FirstOrDefault(); 

    // DO I HAVE A VALID RESULT? 
    if (geoResult != null) 
    { 
     // I DO HAVE A VALID RESULT FOR GEOCODING!! 

     // Defined a new point location for storing my information: 
     Location currentLocation = new Location(); 

     // Set the coordinates: 
     currentLocation.Latitude = geoResult.Locations[0].Latitude; 
     currentLocation.Longitude = geoResult.Locations[0].Longitude; 

     // Your problem was here: 
     callBack(currentLocation.Locations[0]); 

     // ...NEXT SOME SAMPLE CODE... 

     // Set the point on the Bing map with a certain level of zoom: 
     GeoLocationMap.SetView(currentLocation, 10); 

     // Set the location of the visual pin on the map! 
     GeoLocationMapPushpin.Location = currentLocation; 
    } 
} 

は、この情報がお役に立てば幸い！あなたのパラメータは、このようにNULL値であれば

まず第一に、私はあなたがチェックしている見ます