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c# select listview item if two listviews contains it

In my program I have 2 listviews and 1 button.
When I press the button, every listview item in the first listview will be selected in the second listview. The items in the first listview always exist in the second listview, but not the other way around.
I'm having trouble with selecting the items in the second listview. I'm trying to get the index with IndexOf.
foreach (ListViewItem item in firstListView.Items)
{
int index = secondListView.Items.IndexOf(item);
secondListView.Items[index].Selected = true;
}
I always get an error that index is -1 when I click the button. And I don't understand what I'm doing wrong.
SOLUTION
So what I tried to do here finding an index of an item which belongs to a different listview, and it doesn't work like that. Even though the text in both listviews are the same, the listview items are not identically the same because they are reference types.
I was not able to use the Text property because items could have the same text. So the solution I had was putting an unique integer in the Tag property for each ListViewItem. Since integers are value types, I can use that integer to check whether the ListViewItem in the first listview is in the second.
// Loop through each item in the first listview
foreach (ListViewItem item1 in firstListView.Items)
{
// For each item in the first listview, loop through the second listview to find if it's there
foreach (ListViewItem item2 in secondListView.Items)
{
// Check if item1 is identical to item2 by looking at its tag
if (int.Parse(item1.Tag) == int.Parse(item2.Tag))
{
// The item has been found and will be selected!
item2.Selected = true;
}
}
}

You can use such linq query to select items of the second list which exist in the first list too:
var items = from i1 in listView1.Items.Cast<ListViewItem>()
from i2 in listView2.Items.Cast<ListViewItem>()
where i1.SubItems.Cast<ListViewItem.ListViewSubItem>()
.Where((s, i) => s.Text != i2.SubItems[i].Text).Count() == 0
select i2;
items.ToList().ForEach(x => { x.Selected = true; });
Note:
When to try to use secondListView.Items.IndexOf method to find an item which belongs to the firstListView you can not expect it to find the item. The item you are trying to find its index, doesn't exists in second listview's item collection. You should find items using Text property of the item and sub items.

Well the same item obviously cant exist in two different lists.
If the text is the same, then try looking by it:
foreach (ListViewItem listViewItem in l1.Items)
{
var item = l2.Items.Cast<ListViewItem>().Where(lvi => lvi.Text == listViewItem.Text);
item.Selected=true;
}
Or:
foreach (ListViewItem listViewItem in l2.Items.Cast<ListViewItem>()
.Where(lvi => l1.Items.Cast<ListViewItem>().Any(lvi2 => lvi.Text == lvi2.Text))
{
listVieItem.Selected=true;
}

IndexOf returns -1 if it cannot find the object passed to it in the list. My guess is that you have an issue with your equality comparison. Do the objects in the lists implement IComparable? Otherwise they may not be finding the items correctly and are reverting to a bad equality comparison. ListViewItem may not be comparing how you expect.

you can try finding the item by text and then get the index like this
foreach (ListViewItem item in firstListView.Items)
{
var itm = secondListView.FindItemWithText(item.Text);
int index = secondListView.Items.IndexOf(itm);
secondListView.Items[index].Selected = true;
secondListView.Select();
}
what FindItemWithText will do is get the item in secondListView which will be of same name as in firstListView and IndexOf will get the index of item in secondListView
Edit
This solution is good when you have two lists whose items are same and does not include any repetition in name else if you have two items in secondListView with same name FindItemWithText will get the first item only.

Clearing Multi-Selected Items From Listbox C#

What i've tried:
try 1:
for(int x = listBox1.SelectedIndices.Count - 1; x>= 0; x--)
{
int idx = listBox1.SelectedIndices[x];
listBox2.Items.Add(listBox1.Items[idx]);
listBox1.Items.RemoveAt(idx);
}
try 2:
ArrayList tmpArr = new ArrayList();
foreach (object obj in listBox1.SelectedItems)
{
listBox2.Items.Add(obj);
tmpArr.Add(obj);
}
foreach (object obj in tmpArr.ToArray())
{
listBox1.Items.Remove(obj);
}
Also tried everything in the following post: How to remove multiple selected items in ListBox?
Still nothing worked. What am I doing wrong?

var selectedItems = new object[listBox1.SelectedItems.Count];
listBox1.SelectedItems.CopyTo(selectedItems, 0);
foreach (var item in selectedItems)
{
listBox1.Items.Remove(item);
}
or with a bit of LINQ to simplify the code:
foreach (var item in listBox1.SelectedItems.Cast<object>().ToArray())
{
listBox1.Items.Remove(item);
}
The reasoning here is that you get all the selected items and put them into another list first. The original issue is that any change you make to the ListBox will change things like SelectedItems and SelectedIndices. Once you've created an independent array and put the selected items into it, nothing you do to the ListBox will affect that array so you can just enumerate it normally.

listbox1.BeginUpdate();
for (int x = listBox1.SelectedIndices.Count - 1; x >= 0; x--)
{
int idx = listBox1.SelectedIndices[x];
listBox1.Items.RemoveAt(idx);
}
listbox1.EndUpdate();
If you cannot guarantee that every object in the list is unique, then this is the correct way to do it, to ensure that the correct selected items get removed.
If you have multiples of the same object in your listbox, you have to refer to them by "index", otherwise if you remove them by "item" it will remove the first instance of any matching items it finds.
I am in the process of writing a bus route planner which called for replication of the waypoint markers in the list. These were stored as strings, so for example I might have had "w1", "w2", "w3"... "w2" (think of a bus going down a high street, looping round a couple of blocks and then returning down the other side to understand why I have that... I only need waypoint markers in the centre of the road, not in each lane)
If I had selected the last "w2" marker as part of a range and used the selectedItem() method to to remove them, it would have removed the first "w2", not the second one. By using the SelectedIndex() method, it removes based on position, not value, so duplicate values are left safely intact.
I just wanted to add that as I have just been dealing with this very same problem, so saw first hand the problem removing by SelectedItem() caused.

Listbox Selected Item to array

I have a DataTable with 2 columns called "ID" and "Software" that I have used as a DataSource for a lst_Software multiselect listbox.
I'm trying to gather the ID for all the selected items in that have been selected and place that in an int[] array.
Listbox setup:
lst_Software.DataSource = software; //software is a DataTable
lst_Software.DisplayMember = "Software";
lst_Software.ValueMember = "ID";
I've tried below
List<int> list = new List<int>();
for (int i = 0; i < lst_Software.SelectedItems.Count; i++)
{
list.Add(Convert.ToInt32(lst_Software.SelectedValue.ToString()));
}
int[] software = list.ToArray();
I'm finding that I'm only getting the first selected value except it will not iterate through all... I know why though. I'm not using i to get passed through inside the for loop. I'm hoping someone can give me a direction to go to iterate through all the selected values.
Thank you

You're using lst_Software.SelectedValue.ToString() here in the loop so it only returns the one item. You have a for loop but you're not using the index variable. However, all of this is unnecessary really all you need is;
var items = lst_Software.SelectItems;
As that property is already the list of selected items. From there you can cast/convert them as you please.

SelectedValue is just the first selected value. You need to use SelectedItems.

Add element to list before specific element

I have a list of items, lets say 100 items. I need to add another element before the existing element that matches my condition. What is the fastest way and the most performance optimized to do this?
ie.:
foreach (var i in myList)
{
if (myList[i].value == "myValue")
{
myList[i-1] add ("someOtherValue")
}
}
Maybe i should use other container?

First you could find the index of your item using FindIndex method:
var index = myList.FindIndex(x => x.value == "myvalue");
Then Insert at the right point:
myList.Insert(index,newItem);
Note that inserting at a given index pushes everything else forward (think about finding your item at index 0).

Consider using a LinkedList<T>. It has the advantage that inserting or removing items does not require shifting any items. The disadvantage is that items cannot be accessed randomly. You have to traverse the list starting at the first or last item in order to access the items.

myList.Insert(myList.IndexOf("myValue") - 1, "someOtherValue");
You should probably check to make sure myvalue exists first, and it is not in index 0.

int index = myList.IndexOf("myValue");
if (index >= 0)
myList.Insert(index, "myNewValue");
By the way, you should not modify your own collection or list while iterating with for-each (as in your code above).

I presume the list is an array - in which case have you tried doing this with Linq?
string[] mylist = new string[100];
// init the list
List<string> list = keys.ToList();
list.Insert(1,"somethingelse");
mylist = list.ToArray(); // convert back to array if required
if it is a List to begin with, you can skip the conversions and use Insert directly.

Remove the Selected Item From ListView

How can I remove a selected item from a listview?

foreach ( ListViewItem eachItem in listView1.SelectedItems)
{
listView1.Items.Remove(eachItem);
}
where listView1 is the id of your listview.

When there is just one item (Multiselect = false):
listview1.SelectedItems[0].Remove();
For more than one item (Multiselect = true):
foreach (ListViewItem eachItem in listView1.SelectedItems)
{
listView1.Items.Remove(eachItem);
}

listBox.Items.RemoveAt(listBox.SelectedIndex);

Well, although it's a lot late, I crossed that problem recently, so someone might cross with this problem again. Actually, I needed to remove all the selected items, but none of the codes above worked for me. It always throws an error, as the collection changes during the foreach. My solution was like this:
while (listView1.SelectedIndex > 0)
{
listView1.Items.RemoveAt(listView1.SelectedIndex);
}
It won't throw the error as you get position of the last selected item (Currently), so even after you remove it, you'll get where it is now. When there is no items selected anymore, the SelectedIndex returns -1 and ends the loop. This way, you can make sure that there is no selected item anymore, nor that the code will try to remove an item in a negative index.

listView1.Items.Cast<ListViewItem>().Where(T => T.Selected)
.Select(T => T.Index).ToList().ForEach(T => listView1.Items.RemoveAt(T))

Yet another way to remove item(s) from a ListView control (that has GridView) (in WPF)--
var selected = myList.SelectedItems.Cast<Object>().ToArray();
foreach(var item in selected)
{
myList.Items.Remove(item);
}
where myList is the name of your ListView control

foreach (DataGridViewRow dgr in dgvComments.SelectedRows)
dgvComments.Rows.Remove(dgr);