My code correctly identifies listview rows based on a textbox search criteria. However when I try to remove the unwanted row(s) I get an error message:-
InvalidArgument=Value of '-1' is not valid for 'index'.
I would be very grateful if someone could help me resolve this issue.. Thanks in advance.
foreach (ListViewItem item in listView1.Items){
foreach (ListViewItem.ListViewSubItem subItem in item.SubItems){
if (subItem.Text.ToLower().StartsWith(textBox1.Text.ToLower())){
var index = item.Index;
int.TryParse(listView1.Items[index].SubItems[4].Text, out val);
store[pos] = val;
pos++;
count++;
}else{
listView1.Items[index].Remove();
}
}
}
The problem is that you do not calculate your index in clause 'else'
}else{
listView1.Items[index].Remove();
}
You can't remove items from a collection you are iterating through Foreach, c# will throw an error because the collection changed, use for instead, and do it from the end to beginning (so you won't jump items when removing)
Try this approach:
Comments are in the code. Feel free to ask if you need additional explanation.
solution w/ Linq
using System.Linq;
...
//cast ListViewItemCollection as List<ListViewItem> for easier manipulation
var items = listView1.Items.Cast<ListViewItem>();
//first, get all items that don't have text matching with textBox text
List<int> itemIndexes =
items
.Where(item => !item.Text.ToLower().StartsWith(textBox1.Text.ToLower()))
.Select(item => item.Index).ToList();
int val;
//now, with all those indexes do your stuff
itemIndexes.ForEach(index =>
{
int.TryParse(listView1.Items[index].SubItems[4].Text, out val);
store[pos] = val;
pos++;
count++;
});
//lastly, sort indexes descending (for example: 10, 5,4,1) and remove them from listview
itemIndexes
.OrderByDescending(i=>i)
.ToList()
.ForEach(index => listView1.Items.RemoveAt(index));
EDIT: chaged code that it removes items that don't start with text box' text (like OP wanted).
EDIT 2: since you don't want to use Linq, you can solve your problem using plain old lists and loops
Main thing is, as I said in a comment, not to remove items inside of foreach loop but after you found all items that need to be removed.
Code is tested and working (without 4 lines with missing variables store, val etc ...)
solution w/o Linq
//list to hold intem indexes
List<int> itemIndexes = new List<int>();
foreach (ListViewItem item in listView1.Items)
{
foreach (ListViewItem.ListViewSubItem subItem in item.SubItems)
{
var index = item.Index;
if (subItem.Text.ToLower().StartsWith(textBox1.Text.ToLower()))
{
//your code (which doesnt compile since you didn't paste whole code)
//to test this, I had to remove following 4 lines.
int.TryParse(listView1.Items[index].SubItems[4].Text, out val);
store[pos] = val;
pos++;
count++;
}
else
{
itemIndexes.Add(index);
}
}
}
//lastly, sort indexes descending (for example: 10, 5,4,1)
//because if you remove item 1, whole list will shorten and
//you'll get index out of bounds error (in last step when
//trying to remove item with 10 but last index is 7)...
itemIndexes.Reverse();
//... and remove them from listview
foreach (int index in itemIndexes)
{
listView1.Items.RemoveAt(index);
}
tested with sample data - code will remove items that don't start with a, like bbb and dd)
ListView listView1 = new ListView();
listView1.Items.Add("aaa");
listView1.Items.Add("bbb");
listView1.Items.Add("ax");
listView1.Items.Add("dd");
TextBox textBox1 = new TextBox();
textBox1.Text = "a";
Related
I am having trouble with removing an item from a list in c#. My current code is below:
for (int i = current.Count - 1; i >= 0; i--)
{
foreach (ListItem li in sp_list.Items)
{
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
}
}
}
The aim of the code is to compare the existing items in a list box with newly added items so I know which items have just been added. So currently I am getting the current list box items from the database (they are stored here, it is a databound list box), entering these into a list and for each of the list items, comparing them with the items in a list box and if they match, remove the item from the list.
Therefore, in the end, if I add two new entries, the list should only be storing the two newly added values.
The code does not work as the first item is removed fine, but then, the value of i is greater than current.count - and therefore I get an out of range exception!
Could someone help me with this issue? Apologies about the confusing question, it's hard to explain! Thanks
You can do it with Linq. Not sure if casting to ListItem needed (you can remove it)
current.RemoveAll(x => sp_list.Items.Cast<ListItem>()
.Any(li => li.Text == x.uname));
Once you've found the matching value, and removed it from the list, you want to break out of the inner loop to check the next item.
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
break;
}
Your nesting is wrong, I think you wanted,
foreach (ListItem li in sp_list.Items)
{
for (int i = current.Count - 1; i >= 0; i--)
{
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
}
}
}
alternatively, use linq,
// For lookup performance.
var items = new HashSet(sp_list.Items.Select(i => i.text));
current = current.Where(c => !items.Contains(c.uname)).ToList();
How about this:
foreach (ListItem li in sp_list.Items) {
if (current.Contains(li.Text)) {
current.Remove(li.Text);
}
}
Put a break statement after the RemoveAt so you don't remove that item again.
you can travel the list in reverse order and remove items using RemoveAt(i).
also for efficiency purposes you may want to put the ListItem texts in a Set so you can don't have to loop though the sp_list.Items for each of your current items.
I have a CheckedListBox bound to a DataTable. Now I need to check some items programmatically, but I find that the SetItemChecked(...) method only accepts the item index.
Is there a practical way to get an item by text/label, without knowing the item index?
(NOTE: I've got limited experience with WinForms...)
You can implement your own SetItemChecked(string item);
private void SetItemChecked(string item)
{
int index = GetItemIndex(item);
if (index < 0) return;
myCheckedListBox.SetItemChecked(index, true);
}
private int GetItemIndex(string item)
{
int index = 0;
foreach (object o in myCheckedListBox.Items)
{
if (item == o.ToString())
{
return index;
}
index++;
}
return -1;
}
The checkListBox uses object.ToString() to show items in the list. You you can implement a method that search across all objects.ToString() to get an item index. Once you have the item index, you can call SetItemChecked(int, bool);
Hope it helps.
You may try to browse your Datatable. YOu can do a foreach on the DataTabke.Rows property or use SQL syntax as below:
DataTable dtTable = ...
DataRow[] drMatchingItems = dtTable.Select("label = 'plop' OR label like '%ploup%'"); // I assumed there is a "label" column in your table
int itemPos = drMatchingItems[0][id]; // take first item, TODO: do some checking of the length/matching rows
Cheers,
I am answering it very late, I hope it will help someone. If you want to find any item by name we can do it in two steps. First get index of item by text and then we can get actual item with the help of index.
var selectedItemIndex = cbxList.Items.IndexOf("sometext");
var selectedItem = cbxList.Items[selectedItemIndex];
I am trying to get a list of all elements from ListBox if no or one of items is selected or list of selected items if more than 1 are selected. I have written such a code but it doesn't compile :
ListBox.ObjectCollection listBoXElemetsCollection;
//loading of all/selected XMLs to the XPathDocList
if (listBoxXmlFilesReference.SelectedIndices.Count < 2)
{
listBoXElemetsCollection = new ListBox.ObjectCollection(listBoxXmlFilesReference);
}
else
{
listBoXElemetsCollection = new ListBox.SelectedObjectCollection(listBoxXmlFilesReference);
}
So for this piece of code to work I would need to use something like ListBox.SelectedObjectCollection listBoxSelectedElementsCollection; which I do not want because I would like to use it in such an foreach:
foreach (string fileName in listBoXElemetsCollection)
{
//...
}
I'd simply this a bit and not mess with the ListBox ObjectCollections if you don't need to. Since you want to iterate items on your ListBox as strings, why not use a List and load the list how you show:
List<string> listItems;
if (listBoxXmlFilesReference.SelectedIndices.Count < 2) {
listItems = listBoxXmlFilesReference.Items.Cast<string>().ToList();
} else {
listItems = listBoxXmlFilesReference.SelectedItems.Cast<string>().ToList();
}
foreach (string filename in listItems) {
// ..
}
You need to convert SelectedObjectCollection to an array of object[].
ListBox.SelectedObjectCollection sel = new
ListBox.SelectedObjectCollection(listBoxXmlFilesReference);
ListBox.ObjectCollection col = new
ListBox.ObjectCollection(listBoxXmlFilesReference,
sel.OfType<object>().ToArray());
I can see what you're trying to do and it doesnt compile because the type ListBox.ObjectCollection is not the same as ListBox.SelectedObjectCollection - even though in your case they are lists that contain strings the classes themselves are different hence the compile error.
Assuming your items are strings in the listbox you could do:
var items = listBoXElemetsCollection.Items.OfType<string>();
if (listBoXElemetsCollection .SelectedIndices.Count >= 2)
items = listBoXElemetsCollection.SelectedItems.OfType<string>();
foreach(var item in items)
//do stuff
I've just started to use ListView in C#.net.
I got to know how to add items and subitems. Going through the listview I wanted to fetch all the data from a whole column with multiple rows.
I want to know how to do this.
I found this code to list a specific selected data from a row:
ListView.SelectedIndexCollection sel = listView1.SelectedIndices;
if (sel.Count == 1)
{
ListViewItem selItem = listView1.Items[sel[0]];
MessageBox.Show(selItem.SubItems[2].Text);
}
That was helpful but i want to list all the items in a row, may be i want to add all the column items in array?
private string[] GetListViewItemColumns(ListViewItem item) {
var columns = new string[item.SubItems.Count];
for (int column = 0; column < columns.Length; column++) {
columns[column] = item.SubItems[column].Text;
}
return columns;
}
I would recommend some caution against doing this. A ListView is really meant to display information, it is not a great collection class. Getting the data out of it is slow and crummy, it can only store strings. Keep the data in your program in its original form, maybe a List<Foo>. Now it is simple and fast.
foreach (ListViewItem item in listView1.Items) {
// Do something with item
}
you could do this by
foreach(ListViewItem item in listView1.Items)
{
foreach(var subtem in item.SubItems)
{
// Do what ever you want to do with the items.
}
}
I have three sets of listboxes, I move items from lb1 to lb2, from lb3 to lb4 and from lb5 to lb6. The listboxes on the left contains the same items and I don't want the user to be able to submit the page if one or more items from the left listboxes is added to more than one listbox to the right. For example, item A in lb1, lb3 and lb5 can only be saved in either lb2, lb4 or lb6, not in two or three of them.
I want to perform this check before submitting the page (and later on I will add validation with javascript) and I wonder what is the most efficient way to do this.
Add all items to a list and check if there are any duplicates?
Thanks in advance.
Edit:
something like this:
List<string> groupList = new List<string>();
foreach (ListItem item in lbFullAccess.Items)
{
groupList.Add(item.Value.ToString());
}
foreach (ListItem item in lbContributor.Items)
{
groupList.Add(item.Value.ToString());
}
foreach (ListItem item in lblReadOnly.Items)
{
groupList.Add(item.Value.ToString());
}
Well, there's a hundred different ways you could do it. Absolutely nothing wrong with your suggestion of iteration.
You could have a little fun with LINQ:
public bool AreAllValuesUnique()
{
// Build up a linq expression of all of the ListItems
// by concatenating each sequence
var allItems = lbFullAccess.Items.Cast<ListItem>()
.Concat(lbContributor.Items.Cast<ListItem>())
.Concat(lbReadOnly.Items.Cast<ListItem>());
// Group the previous linq expression by value (so they will be in groups of "A", "B", etc)
var groupedByValue = allItems.GroupBy(i => i.Value);
// Finally, return that all groups must have a count of only one element
// So each value can only appear once
return groupedByValue.All(g => g.Count() == 1);
}
Not really sure about the performance of calling Cast (converting each element of the ListItemCollection to a ListItem, resulting in an IEnumerable) on each collection, but it is probably negligible.