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Changing SelectedItem property of a ListView programatically

I have a 2 ListViews with same items in both of them. What I want to do is that when a selection is made in one ListView, the same selection should be reflected in the other ListView also. The two ListViews are bound to two different ViewModels but both the ViewModels implement the same interface.
I've overridden the Equals methods in both ViewModels.
The two ListViews are on different XAML pages. The first ListView say LV1 is in Page1.xaml and LV2 is in Page2.xaml. What I want is that when I am changing the selection in LV2 the selection in LV1 should also change( one way only ). I've set x:FieldModifier="public" on LV1 and exposing through a static property of Page1 like this:
public sealed partial class Page1 : Page
{
public static Page1 page1 { get; private set; }
}
And on Page2, I have this :
private async void LV2_ItemClick(object sender, ItemClickEventArgs e)
{
var selected = e.ClickedItem as ISomeCommonInterface;
//Comparision is successful --> Contains() always returns corect value;
if (Page1.page1.LV1.Items.ToList().Contains(selected))
{
Page1.page1.LV1.SelectedItem = null; // this works
Page1.page1.LV1.SelectedItem = selected; // this doesn't work
}
}
I've found that inside the if condition, assignment to null changes the SelectedItem of LV1 to null but the next line doesn't change it to selected ( it remains null ).

add after assignment:
Page1.page1.LV1.Select();

This works for me:
private void LV1_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
var selected = (sender as ListView).SelectedItem as string;
int index = -1;
for (int i = 0; i < LV2.Items.Count(); i++)
{
if (LV2.Items[i] as string == selected){
index = i;
break;
}
}
// The if becomes obsolete here, it could be replaced by
// if(index >= 0)
if (LV2.Items.ToList().Contains(selected))
{
LV2.SelectedIndex = index;
}
}
There is probably an easier way of getting the index of LV1's SelectedItem in LV2, but it should be enough to get you on the right track.
You can check out the minimal testing app I created that shows that SelectedItem works too.

Method 1 - SelectionMode="Multiple" - both ListViews in sync
You should subscribe the SelectionChanged event on both ListViews - item may not get selected only by click - and there (when selection is changed) you should sync the selection.
private void SyncSelection(object sender, SelectionChangedEventArgs e)
{
ListView listViewToAdd = ReferenceEquals(sender, firstListView) ? secondListView : firstListView;
foreach (var item in e.AddedItems)
{
if (!listViewToAdd.SelectedItems.Contains(item))
{
listViewToAdd.SelectedItems.Add(item);
}
}
foreach (var item in e.RemovedItems)
{
listViewToAdd.SelectedItems.Remove(item);
}
}
Method 2 - SelectionMode="Multiple" - update one after selecting in the other
You should subscribe the SelectionChanged event only on the ListView where items could be selected.
private void SyncSelection(object sender, SelectionChangedEventArgs e)
{
foreach (var item in e.AddedItems)
{
secondListView.SelectedItems.Add(item);
}
foreach (var item in e.RemovedItems)
{
secondListView.SelectedItems.Remove(item);
}
}
Method 3 - SelectionMode="Single"
Subscribe the SelectionChanged event on both if you want to make them be in sync or only on the selectable one if you only want to update the second based on the first.
private void SyncSelection(object sender, SelectionChangedEventArgs e)
{
ListView senderListView = (ListView)sender;
ListView listViewToAdd = ReferenceEquals(sender, firstListView) ? secondListView : firstListView;
listViewToAdd.SelectedItem = senderListView.SelectedItem;
}
You may need to replace var with your interface to make it work.

Remove items from ListBox if item exists in another ListBox

I am trying to remove numerical items from a ListBox if those values exist in another ListBox. My code does not seem to work and I could not locate any help online. ListBox1 is populated by Array and ListBox2 is populated from a DataSet table (fyi).
Also for reference: I'm not adding and items to a listbox or selecting...simply just want to compare both and remove ListBox2 items from ListBox1 if they exist all automatically with a press of a button. Thank you,
private void button1_Click(object sender, EventArgs e)
{
foreach (int item in listBox1.Items)
{
if (listBox2.Items.Contains(item))
{
listBox1.Items.Remove(item);
}
}
}

Well you're only referencing one list box in your code - I suspect you would want:
private void button1_Click(object sender, EventArgs e) {
foreach (int item in listBox1.Items)
{
if (listBox2.Items.Contains(item)) // notice change of reference
{
listBox1.Items.Remove(item);
}
}
However that would cause an error since you're modifying the ListBox while you're iterating over it's items. One way to safely remove items it to iterate backwards over the colection:
for (int i = listBox1.Items.Count - 1; i >= 0; i--)
{
int item = listBox1.Items[i];
if (listBox2.Items.Contains(item)) // notice change of reference
{
listBox1.Items.RemoveAt(i);
}
}

#D Stanley
Thank you for your help and explanation. #Yuriy - Thank you for the clarification, the
i >= 0
works great. I also converted to listbox to int32. Below is the fully working code:
private void button1_Click(object sender, EventArgs e)
{
for (int i = listBox1.Items.Count - 1; i>= 0; i--)
{
int item = Convert.ToInt32(listBox1.Items[i]);
if (listBox2.Items.Contains(item))
{
listBox1.Items.Remove(item);
}
}
}

Remove items from ListBox when DataSource is set

See I have a HashSet with several values, this values can contain for example numbers like 4141234567, 4241234567, 4261234567 and so on. I put a radioButton1 in my UserControl and I want when I click this just the numbers with 414 and 424 remains on my ListBox, for that I wrote this code:
private void radioButton1_CheckedChanged(object sender, EventArgs e)
{
var bdHashSet = new HashSet<string>(bd);
if (openFileDialog1.FileName.ToString() != "")
{
foreach (var item in bdHashSet)
{
if (item.Substring(1, 3) != "414" || item.Substring(1, 3) != "424")
{
listBox1.Items.Remove(item);
}
}
}
}
But when I run the code I get this error:
Items collection cannot be modified when the DataSource property is set.
What is the proper way to remove the non wanted items from the list without remove them from the HashSet? I'll add later a optionButton for numbers that begin with 0416 and 0426 and also a optionButton to fill the listBox with original values, any advice?

try
private void radioButton1_CheckedChanged(object sender, EventArgs e)
{
var bdHashSet = new HashSet<string>(bd);
listBox1.Datasource = null;
listBox1.Datasource = bdHashSet.Where(s => (s.StartsWith("414") || s.StartsWith("424"))).ToList();
}

Try this:
private void radioButton1_CheckedChanged(object sender, EventArgs e)
{
var bdHashSet = new HashSet<string>(bd);
listBox1.Datasource = bdHashSet.Select(s => (s.Substring(1, 3) == "414" || s.Substring(1, 3) == "424"));
//After setting the data source, you need to bind the data
listBox1.DataBind();
}

I think that you can select the elements with linq and then reassign the listBox with the result. In that way you dont need to remove elements from the list and you can keep the elements of the HashSet.

You can use BindingSource object. Bind it with DataSource and then use the RemoveAt() method.

Try this :
DataRow dr = ((DataRowView)listBox1.SelectedItem).Row;
((DataTable)listBox1.DataSource).Rows.Remove(dr);

Select index from listview

I'm having some problem to get the index of the selected row in a listview. I wonder why this code isn't working? I get a red line below the SelectedIndex
private void lvRegAnimals_SelectedIndexChanged(object sender, EventArgs e)
{
int index = lvRegAnimals.SelectedIndex;
string specialData = motelManager.GetInfoFromList(index);
UppdateSpecialData(specialData);
}
Help is preciated. Thanks!
EDIT:
For some strange reason I get two messages when I click on one of the lines in the listView!? First I get the previous number and then the number for the last clicked line. What could be wrong?
private void lvRegAnimals_SelectedIndexChanged(object sender, EventArgs e)
{
int index = lvRegAnimals.FocusedItem.Index;
MessageBox.Show(Convert.ToString(index));
}
It's working now when I added a check like this:
if(lvRegAnimals.SelectedIndices.Count > 0)

Because ListView doesn't contain any SelectedIndex, instead there is a property of SelectedIndices.
var indices = lvRegAnimals.SelectedIndices;
//indices[0] you can use that to access the first selected index
ListView.SelectedIndices
When the MultiSelect property is set to true, this property returns a
collection containing the indexes of all items that are selected in
the ListView. For a single-selection ListView, this property returns a
collection containing a single element containing the index of the
only selected item in the ListView.

private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
// Acquire SelectedItems reference.
var selectedItems = listView1.SelectedItems;
if (selectedItems.Count > 0)
{
// Display text of first item selected.
this.Text = selectedItems[0].Text;
}
else
{
// Display default string.
this.Text = "Empty";
}
}

Try :
listView1.FocusedItem.Index
This give you the index of the selected row.

There is another thread like this one, but here it goes again.
It can return NULL. Also the SelectedIndexChanged event can be FIRED TWICE. And the first time, there nothing selected yet.
So the only safe way to find it is like this:
private void lv1_SelectedIndexChanged(object sender, EventArgs e)
{
if (lv1.FocusedItem == null) return;
int p = lv1.FocusedItem.Index;
... now int p has the correct value...

The ListView is a darn hassle to work with sometimes.
A simple solution i've used is a for loop that checks for the
selected Item.
I've put my solution in the "When index change trigger" within the ListView.
Example:
int sel_item = 0; //an int to store the selected item index.
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
for (int i = 0; i < listView1.Items.Count; i++)
{
if (listView1.Items[i].Selected == true)
{
sel_item = i;
}
}
}
This would ofcourse only work correctly with the "Multiselection" option set as false.

ListBox Item Removal

I have a WPF window that manages sets of configurations and it allows users to edit a configuration set (edit button) and to remove a configuration set (remove button). The window has a ListBox control that lists the configuration sets by name and its ItemsSource has a binding set to a list of configuration sets.
I'm trying to remove the item in the code behind file for the window..
private void RemoveButton_Click(object sender, RoutedEventArgs e)
{
var removedItems = configSetListBox.SelectedItems;
foreach(ConfigSet removedItem in removedItems)
{
configSetListBox.Items.Remove(removedItem);
}
}
My code yields an invalid operation exception stating "Access and modify elements with ItemsControl.ItemsSource instead." What property should I be accessing to properlyremove items from the ListBox? Or is there possibly a more elegant way to handle this in WPF? My implementation is a bit WinForm-ish if you will :)
Solution
private void RemoveButton_Click(object sender, RoutedEventArgs e)
{
foreach(ConfigSet removedItem in configSetListBox.SelectedItems)
{
(configSetListBox.ItemsSource as List<ConfigSet>).Remove(removedItem);
}
configSetListBox.Items.Refresh();
}
In my case I had a List as the ItemSource binding type so I had to cast it that way. Without refreshing the Items collection, the ListBox doesn't update; so that was necessary for my solution.

use:
private void RemoveButton_Click(object sender, RoutedEventArgs e)
{
foreach(ConfigSet item in this.configSetListBox.SelectedItems)
{
this.configSetListBox.ItemsSource.Remove(item); // ASSUMING your ItemsSource collection has a Remove() method
}
}
Note: my use of this. is just so it as it is more explicit - it also helps one see the object is in the class namespace as opposed to variable in the method we are in - though it is obvious here.

This is because , you are modifying a collection while iterating over it.
if you have binded item source of listbox than try to remove the items from the source

this was answered here already.
WPF - Best way to remove an item from the ItemsSource
You will need to implement an ObservableCollection and then whatever you do to it will be reflected in your listbox.

I Used this logic to preceed. And it worked.
you may want to try it.
private void RemoveSelectedButton_Click(object sender, RoutedEventArgs e) {
if (SelectedSpritesListBox.Items.Count <= 0) return;
ListBoxItem[] temp = new ListBoxItem[SelectedSpritesListBox.SelectedItems.Count];
SelectedSpritesListBox.SelectedItems.CopyTo(temp, 0);
for (int i = 0; i < temp.Length; i++) {
SelectedSpritesListBox.Items.Remove(temp[i]);
}
}

for (int i = lstAttachments.SelectedItems.Count - 1; i >= 0; i--)
{
lstAttachments.Items.Remove(lstAttachments.SelectedItems[i]);
}
Simplest way to remove items from a list you iterate through is going backwards because it does not affect the index of items you are moving next to.