Xamarin Listview 仅添加 1 项我的列表中有 2 项

Posted 2023-04-13

【中文标题】Xamarin Listview 仅添加 1 项我的列表中有 2 项

【英文标题】：Xamarin Listview only adding 1 item my List has 2 items on it

【发布时间】：2021-12-19 19:20:21

【问题描述】：

我有一个 listview 和一个通过 Bluethoot 连接将项目获取到 Radio 设备的方法，当方法结束时，我的 itemsList 中有两个项目，但我的 ListView 上只显示一个，该项目在我之前不可见出于某种原因点击屏幕。

关于如何在 ListView 中同时显示我的两个项目有任何帮助吗？

我认为这与我处理 EventRead 和 EventStopped 的方式有关，也许它没有时间更新

public partial class ReadAnyPage : ContentPage
    
        IRadioPlatform _platform;
        DropdownTypes dropdownTypes;

        Task<List<ChoiceConnectEndpoint>> _readAnyComplete;
        public event EventHandler OnStopped;
        public event EventHandler<Itron.Mobile.Radio.Communication.SRead.HandledEventArgs<ChoiceConnectEndpoint>> readEndpoints;
        private List<JsonDict> itemsList = new List<JsonDict>();
        string bleName, blePort;

        public ReadAnyPage()
        
            InitializeComponent();
            BindingContext = this; //Added this

            _platform = DependencyService.Get<IRadioPlatform>();

            dropdownTypes = new DropdownTypes();

            bleName = Preferences.Get("ble_name", "");
            blePort = Preferences.Get("ble_port", "");

            CancellationTokenSource tokenSource = new CancellationTokenSource();
            CancellationToken token = tokenSource.Token;

            listView.ItemsSource = itemsList;

            ReadAnyNear(tokenSource, token);
        

        private void ReadAnyNear(CancellationTokenSource tokenSource, CancellationToken token)
        
            var loading = UserDialogs.Instance.Loading("Reading Endpoints...", onCancel: tokenSource.Cancel, "\n\n" + Resx.Resources.Cancel, true, MaskType.Black);

            try
            
                // Set new IMR
                IMRRadioservice imrRadioService = new IMRRadioService(_platform);

                imrRadioService.Name = bleName;
                imrRadioService.Port = blePort;string

                readEndpoints += EventRead;
                OnStopped += EventStopped;

                _readAnyComplete = imrRadioService.ReadAny(token, readEndpoints, OnStopped);

            
            catch (Exception ex)
            
                DisplayAlert("Error", dropdownTypes.OnConvertErrorEX(ex.Message), "ok", "cancel");

            

            loading.Hide();
        

        private void EventRead(object sender, EventArgs e)
        
            Console.WriteLine("READ READ");

            try
            
                Itron.Mobile.Radio.Communication.SRead.HandledEventArgs<ChoiceConnectEndpoint> item = (Itron.Mobile.Radio.Communication.SRead.HandledEventArgs<ChoiceConnectEndpoint>)e;

                JsonDict jsonDict = new JsonDict();

                jsonDict.RadioNumber = item.Data.EndpointId.ToString();
                jsonDict.MeterType = item.Data.MarketType.ToString();
                jsonDict.Read = ((Endpoint100G)item.Data).Reading.Read.ToString();
                jsonDict.ModuleType = item.Data.EndpointTypeName;
                jsonDict.ServiceType = item.Data.MarketType.ToString();

                itemsList.Add(jsonDict);
                Console.WriteLine("Count:" + itemsList.Count);
                listView.ItemsSource = itemsList;
            
            catch (Exception ex)
            
                Console.WriteLine("Error:" + ex.Message);
            
        

        private void EventStopped(object sender, EventArgs e)
        
            Console.WriteLine("STOPPED");
        

        private async void ListView_ItemTapped(object sender, ItemTappedEventArgs e)
        
            
        

        private void ListView_Refreshing(object sender, EventArgs e)
        
            OnRefreshDevicesList();
        

        private void OnRefreshDevicesList()
        
            
            listView.EndRefresh();
        
    

【问题讨论】：

itemsList 应该是 ObservableCollection<T>，而不是 List<T>

并且不要重新分配ItemsSource

感谢@Jason 做到了，如此简单但我看不到它

【参考方案1】：

感谢@Jason 从这里解决

private List<JsonDict> itemsList = new List<JsonDict>();

到这里

private ObservableCollection<JsonDict> itemsList = new ObservableCollection<JsonDict>();

【讨论】：

考虑将其标记为答案，因为它对其他人有帮助。