C#

ListView lv = new ListView();
lv.Items.Add(new ListViewItem("Hello"));

foreach (ListViewItem items in lv.Items)
{
    ListViewItem lvItem = (ListViewItem)items.Clone();

    listView1.Items.Add(lvItem);
}

teejayem wrote:

When i debugged it i did see it get copied over though.

Luc Pattyn wrote:

There are two ways to avoid this speed trap:
- add a range of items
- suspend and resume layout

DataSet ds = new DataSet();
ds.Tables.Add("Table 1");
ds.Tables[0].Columns.Add("Column 1");
ds.Tables[0].Rows.Add("Hello");
ds.Tables[0].Rows.Add("World");

foreach (DataRow row in ds.Tables[0].Rows)
    listView1.Items.Add(row.ItemArray[0].ToString());

Tarakeshwar Reddy wrote:

Why do you want to add it to one listview and again add it to another listview?

Tarakeshwar Reddy wrote:

You can use a listviewitem and add it to both the listview's if that is what your trying to do.

brahmma wrote:

No, I've added some items to a listview in the memory, and then I want all these items to be added to the one in the UI.

Tarakeshwar Reddy wrote:

You will have to add 1000 items in the listview object in memory and again re-add 1000 items to the listview in the UI, thats almost like adding 2000 items and that would surely slow down the app.

brahmma wrote:

You see, I was trying to find out if I could copy a listview object in memory to another.

brahmma wrote:

One is in the memory, and another is in the UI.

Regards,

Satips.

brahmma wrote:

listView1 = lv; //Can I equate it like this?

form.Controls.Add(listView1);

S. Senthil Kumar wrote:

That line does not copy the contents, it just makes listView1 refer to whatever lv was referring to. After executing that statement, both listView1 and lv refer to the same object.

S. Senthil Kumar wrote:

Making listView1 refer to another object by writing listView1 = lv will not change the ListView object in the Controls collection.

brahmma wrote:

Actually, I am retrieving data from a database and populating a ListView object with it. The UI operation seems to be slow and so I thought I would do it in the memory

ListView listView;

delegate void UpdateListViewDelegate(List<ListViewItem> listViewItems);
void DBDataLoaderThread()
{
  List<ListViewItem> items = new List<ListViewItem>();
  ...
  while (dataReader.Read())
  {
     items.Add(new ListViewItem(...));
  }
  listView.BeginInvoke(new UpdateListViewDelegate(UpdateListView), new object[] { items } );
}

void UpdateListView(List<ListViewItems> listViewItems)
{
   foreach(ListViewItem item in listViewItems)
   {
      listView.Items.Add(item);
   }
}

void UpdateListView(List<ListViewItems> listViewItems)
{
   listView.BeginUpdate();
   foreach(ListViewItem item in listViewItems)
   {
      listView.Items.Add(item);
   }
   listView.EndUpdate();
}

S. Senthil Kumar wrote:

If it's the latter, you can use BeginUpdateListView and EndUpdate after it - this will prevent the ListView from repainting after adding each element.

sulabh2020 wrote:

adding a button to datagridview