Question

is it possible to get the text values of specific column in a listview in form of array without using a loop function? lets say I have a listview contains 2 columns and 5000 records. what I want is to get all the texts under column 2 only but without using a loop. I know I can accomplish this with a loop but it takes ages if I had 5000+ records..

any ideas?

Answer 1

I feel your pain and I’ve personally experienced how slow a ListViewItemsCollection can be.

You can access the second column of a ListView without a for loop like this:

string[] column1 = this.listView1.Items.Cast<ListViewItem>().Select(item => item.SubItems[1].Text).ToArray();

but this isn’t any faster than a for loop. In fact it’s a little bit slower! Other tricks like trying to use ListViewItemsCollection.CopyTo also fail miserably.

A major problem with the ListView is that is pathologically slow when used as a data structure. The property ListView.Items looks like a data structure and you can use it like a data structure but any way you slice it:

• data goes in but it doesn’t come out fast.

So if you follow alexD’s advice you will find that a real data structure will outperform a ListViewItemCollection by orders of magnitude. The moral of the story is if you want to query the data in a ListViewItemCollection fast, you have no alternative than to keep a fast copy outside of the ListView. Practically any data structure will do, e.g.

• a string[][]
• a string[,]
• a List<List<string>>
• a List<string[]> or even
• a List<Tuple<string, string>>.

These can all store the same data as a two-column ListView and will be instantaneously fast by comparison to using the ListView as a data structure. It is inconvenient but that is the price we must pay for speed.