如何在 WPF 中使用列表框项目？

Question

I am trying to learn Wpf. When the program runs, it gives me the "no listbox source" error. I am working on a Wpf design but I just started.

The features I have added to the listbox externally, how can I show them as sources. I have no idea about this. I think I have been researching this for 2 hours but I have not found any answer. I have some problems with English. I hope I won't bother you. All details of my codes are below. Thank you in advance for helping.

//Note : My Class : (public partial class MainWindow : Window)
public void btnListAdd_Click(object sender, RoutedEventArgs e)
        {           
            CronList1.Items.Clear();     // ListBox      <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 
            OpenFileDialog f = new OpenFileDialog();

            if (f.ShowDialog().HasValue == true)
            {
                List<string> lines1 = new List<string>();
                using (StreamReader r = new StreamReader(f.OpenFile()))
                {

                    string line;
                    while ((line = r.ReadLine()) != null)
                    {

                        CronList1.Items.Add(line); // ListBox      <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 


                    }
                }
            }
        }

2 : I then try to read all in the CronList. I run the method in the class.

CronEvent cronEvent = new CronEvent();
Task.Run(cronEvent.Cron1);

3 :My Code Dont Run!

public async Task Cron1()
        { 
            int sayix = 1;
            while (true)
            {
                try
                {

                 (HttpWebRequest) rq WebRequest.Create(mainWindow.CronList1.Items[sayix].ToString());
                    rq .Proxy = WebRequest.GetSystemWebProxy();
                    rq .AllowAutoRedirect = false;
                    rq .Timeout = 10000;

                    HttpWebResponse rply= (HttpWebResponse)rq.GetResponse();
                    StreamReader streamReader = new StreamReader(rply.GetResponseStream());
                    rply.Close();
                    streamReader.Close();

                    mainWindow.CronList1.SelectedIndex = sayix;

                    sayix++;
                    if (sayix == mainWindow.CronList1.Items.Count)
                    {
                        sayix = 0;
                    }
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.Message);
                }

                await Task.Delay(TimeSpan.FromSeconds(Convert.ToDouble(mainWindow.txtTime.Text)));

            }
        }

WPF Listbox Code

<ListBox Name="CronList1" Height="390" Margin="2,7,4,0" VerticalAlignment="Top" BorderBrush="Red" Cursor="Arrow" IsSynchronizedWithCurrentItem="False" BorderThickness="1" ClipToBounds="True" SnapsToDevicePixels="True" Grid.Row="1" Grid.RowSpan="2" Grid.Column="1">

                        <ListBox.ItemBindingGroup>
                            <BindingGroup/>
                        </ListBox.ItemBindingGroup>
                        <ListBox.Effect>
                            <hc:BrightnessEffect/>
                        </ListBox.Effect>


                    </ListBox>

Answer 1

I would recomend using a "data binding" in a ViewModel to make the code more readable.

You create a class (eg MainViewModel) and in there you create an ObservableCollection where you add or remove items from.

In the View (xaml file) you then add this ViewModel as a Source and use a Binding to add the items of the collection to your ListView.

Here is an example

Let me know if you can't get it to work.