错误的退货类型

Question

我不明白为什么我得到一个错误:

'System.Collections.Generic.List Notify.MainPage.webClient_OpenReadCompleted(object,System.Net.OpenReadCompletedEventArgs)'返回类型错误

码:

webClient.OpenReadCompleted += webClient_OpenReadCompleted;

和:

private List<SightingType> webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
        {
            DataContractJsonSerializer ser = null;
            var sightingT = new List<SightingType>();
            try
            {
                ser = new DataContractJsonSerializer(typeof(ObservableCollection<SightingType>));
                ObservableCollection<SightingType> sightingTypes = ser.ReadObject(e.Result) as ObservableCollection<SightingType>;
                foreach (var sightingType in sightingTypes)
                {
                    sightingT.Add(sightingType);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

            return sightingT;
        }

有谁知道我哪里出错了？

Answer 1

事件处理程序的返回类型应为void:

private void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
        {

在另一端没有任何东西可以接收返回数据.