这种方法:异步和匿名类型
private async Task readFileInfo(string folderId)
有另一种方法的调用:
importCount = await VM.importVehicles(myXDoc);
定义如下:(注:我改变它从一个for循环的每一个,但我会得到类似的结果)。当我踏上过它的iVehicle
被突出显示,但然后直接转到for语句
Object reference not set to an instance of an object.
:
public async Task<Int32> importVehicles(XDocument importXMLDocument)
{
var Importedvehicles = from vehicle in importXMLDocument.Descendants("vehicle")
select new
{
VehicleName = vehicle.Element("VehicleName").Value,
VehicleYear = vehicle.Element("VehicleYear").Value,
Odometer = vehicle.Element("Odometer").Value,
LicensePlate = vehicle.Element("LicensePlate").Value,
OilWeight = vehicle.Element("OilWeight").Value,
OilQuantity = vehicle.Element("OilQuantity").Value,
OilFilterModelNumber = vehicle.Element("OilFilterModelNumber"),
AirFilterModelNumber = vehicle.Element("AirFilterModelNumber"),
OilChangedDate = vehicle.Element("OilChangedDate"),
OilChangedOdometer = vehicle.Element("OilChangedOdometer"),
NextOilChangeDate = vehicle.Element("NextOilChangeDate"),
NextOilChangeOdometer = vehicle.Element("NextOilChangeOdometer"),
SettingDistance = vehicle.Element("SettingDistance"),
SettingMonths = vehicle.Element("SettingMonths"),
};
Int32 vehicleId;
vehicleId = await getMaxVehicleId();
try
{
foreach (var item in Importedvehicles)
{
vehicle myImportedVehicle = new vehicle();
myImportedVehicle.VehicleId = vehicleId += 1;
myImportedVehicle.ImagePath = "Assets/car2.png";
myImportedVehicle.VehicleName = item.VehicleName;
myImportedVehicle.VehicleModel = item.VehicleName;
myImportedVehicle.VehicleYear = short.Parse(item.VehicleYear);
myImportedVehicle.CurrentOdometer = Convert.ToInt32(item.Odometer);
myImportedVehicle.LicensePlate = item.LicensePlate;
myImportedVehicle.LastOilChangedDate = Convert.ToDateTime(item.OilChangedDate.Value.ToString()).ToString("d");
myImportedVehicle.LastOilChangedOdometer = (Int32)item.OilChangedOdometer;
myImportedVehicle.ReminderDistance = (Int32)item.SettingDistance;
myImportedVehicle.ReminderMonths = (Int32)item.SettingMonths;
vehicleInformation myImportVI = new vehicleInformation();
myImportVI.OilWeight = item.OilWeight;
myImportVI.OilAmount = item.OilQuantity;
myImportVI.OilFilterNumber = item.OilFilterModelNumber.Value.ToString();
myImportVI.AirFilterNumber = item.AirFilterModelNumber.Value.ToString();
myImportedVehicle.vehicleInfo = myImportVI;
m_vehicles.Add(myImportedVehicle);
}
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.Message.ToString());
}
await SaveList();
return Importedvehicles.Count();
}
我发现了一个错误。然后它看起来错误,因为它还没有得到iVehicle
的结果。
你究竟在哪里返回任何东西? – BrokenGlass 2013-02-15 01:55:52
我不认为这与'async/await'有什么关系。我敢打赌,由于**推迟执行**,在你的查询中有一些是空的。首先进行调试。 – 2013-02-15 01:57:57
简短说明,但* complete *示例(其他人可以编译并运行)显示问题的代码。 – svick 2013-02-15 02:40:15