指定的强制转换在 Xamarin 表单中无效

Question

有谁知道当出现像 Specified cast is not valid 这样的错误时会发生什么？我评论了错误发生的那一行

private async void GetEmployee()
 {
     var _token = await GetAccessToken();            
     using (var _client = new HttpClient())
     {
         var _uri = "domain here";

         _client.BaseAddress = new Uri(_uri);
         _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
         _client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _token);

         var _response = await _client.GetAsync("endpoint here'");

         var Emp = JsonConvert.DeserializeObject<Employee>(await _response.Content.ReadAsStringAsync());
         Employee = new ObservableCollection<Employee>((IEnumerable<Employee>)Emp); //Im having error on this line
     }
 }

 ObservableCollection<Employee> _employee;
 public ObservableCollection<Employee> Employee
 {
     get
     {
         return _employee;
     }
     set
     {
         _employee = value;
         OnPropertyChanged();
     }
 }

Answer 1

如何改变这个：

Employee = new ObservableCollection<Employee>((IEnumerable<Employee>)Emp);

到这里：

Employee = new ObservableCollection<Employee>(new[] {Emp});

See .NET Fiddle example.

See ObservableCollection documentation.

---

new[] { ... } 是new Employee[] { ... } 的缩写，并使用{ 和} 中的初始值创建一个新数组。

See array documentation.