列表框-添加两个相同的项目-WPF

Question

I have a ListBox (WPF) and I am adding to it strings at runtime.... If I try to add string that is already exists in the ListBox it throws me an exception..... telling that this item is already in the ListBox.... How can I add the same strings to ListBox ? Because I have situations in my application when I do have to add 2 identical strings.... thanks....

The ListBox -

<ListBox x:Name="listBox_MyListBox" Height="Auto" Width="Auto" Background="Transparent" MaxHeight="170" BorderThickness="0" Margin="3">
                        <ListBox.ItemTemplate>
                            <DataTemplate>
                                <TextBlock Margin="3" Padding="2" Text="{Binding}" TextAlignment="Center" FontSize="13"/>
                            </DataTemplate>
                        </ListBox.ItemTemplate>
                    </ListBox>

in the code behind I add the string like that -

 this.listBox_MyListBox.Items.Add(text.ToString());

Answer 1

why not a simple list?

the easy not mvvm way:

 public List<string> MyItems {get; set;}

 listBox_MyListBox.ItemsSource = MyItems;

 MyItems.Add("t1");
 MyItems.Add("t2");
 MyItems.Add("t1");//again

i would use a viewmodel with your list and bindging to the listbox. but the code above will work too.

Answer 2

Yes, you can add duplicate items to listbox, it allows without any issue Example:

private void Window_Loaded ( object sender, RoutedEventArgs e )
{
   listBox_MyListBox.Items.Add ( "demo" );
   listBox_MyListBox.Items.Add ( "demo" );            
}

Note: It would not let you add duplicate if you are using any of data sources which dont allow duplicate: Dictionary or Hashtable may not allow duplicate entries, if that is the case with you then choose List or datatable as datasource