Question

我很困惑。我在包含GeoRoot.features.Add(Feat);的行上遇到了对象引用错误，这对我来说就像一个列表。我做错了什么？

public double getDistance(GeoCoordinate p1, GeoCoordinate p2)
{
    double d = p1.Latitude * 0.017453292519943295;
    double num3 = p1.Longitude * 0.017453292519943295;
    double num4 = p2.Latitude * 0.017453292519943295;
    double num5 = p2.Longitude * 0.017453292519943295;
    double num6 = num5 - num3;
    double num7 = num4 - d;
    double num8 = Math.Pow(Math.Sin(num7 / 2.0), 2.0) + ((Math.Cos(d) * Math.Cos(num4)) * Math.Pow(Math.Sin(num6 / 2.0), 2.0));
    double num9 = 2.0 * Math.Atan2(Math.Sqrt(num8), Math.Sqrt(1.0 - num8));
    return (6376500.0 * num9);
}

public GeoRootObject GetRndNearybyLocationList(double lat, double lon, int meters)
{
    GeoRootObject GeoRoot=new GeoRootObject();


    LocationObject thisRndLocation = new LocationObject();
    List<LocationObject> locationsList = new List<LocationObject>();

    //List<GeoJSON.Net.Geometry.GeographicPosition> Positions = new List<GeoJSON.Net.Geometry.GeographicPosition>();

    Random rnd = new Random();
    int dice = rnd.Next(1, 7);


    for (int i = 1; i <= dice; i++)
    {
        thisRndLocation = getLocation(lat, lon, meters);
        GeoRoot.type = "FeatureCollection";
        Feature Feat = new Feature();
        Feat.type = "Point";
        List<double> coOrds = new List<double>();
        coOrds.Add(thisRndLocation.lon);
        coOrds.Add(thisRndLocation.lat);
        GeoRoot.features.Add(Feat);
        Geometry Geometry = new Geometry();
        Geometry.coordinates = (coOrds);
        Geometry.type = ("Point");
        Feat.geometry = Geometry;
        Feat.id = i;
        GeoRoot.features.Add(Feat);

    }
    return GeoRoot;
}

以下是上面方法片段中调用的类

public class Geometry
{
    public string type { get; set; }
    public List<double> coordinates { get; set; }
}

public class Properties
{
    public string popupContent { get; set; }
}

public class Feature
{
    public Geometry geometry { get; set; }
    public string type { get; set; }
    public Properties properties { get; set; }
    public int id { get; set; }
}

public class GeoRootObject
{
    public string type { get; set; }
    public List<Feature> features { get; set; }
}

Answer 1

您似乎遇到的主要问题是您尝试在空列表上调用.Add()方法。如果您遇到问题，请尝试添加GeoRoot.features = new List<Feature>();

将项目添加到列表时抛出异常

1 个答案: