在C＃中从ListView检索数据时花费更多时间

Question

Consider the ListView item Having two columns with more than 35,000 rows inserted already. Now the user selects the any 30,000 rows from the ListView. I want all the Selected Items data let's Say (Item,Subitems)

Here is my code.

ListView Name : lstViewData

        List<string> l_lstData = new List<String>();
        for(int l_nItem =0;l_nItem<lstViewData.SelectedItems.Count;l_nItem++)
        {
          l_lstData.Add(lstViewData.SelectedItems[l_nItem].Text+              
          lstViewData.SelectedItems[l_nItem].SubItems[1].Text);
        }

It Will take more than Half an hour in my PC(Configuration - IntelCore2Duo @2.40GHZ).Since the no. of selected items is morethan 30,000 in ListView

Kindly tell me the solution If any one knows?

Answer 1

You are using the + operator:

l_lstData.Add(lstViewData.SelectedItems[l_nItem].Text+lstViewData.SelectedItems[l_nItem].SubItems[1].Text);

you should NEVER in a case where there is a lot of operations use the + operator on strings, as they are immutable. You should use a StringBuilder .

l_lstData.Add(sbuilder.Append(lstViewData.Seleteditems[l_nItem].Text).Append(lstViewData.SelectedItems[l_nItem].SubItems[1].Text).ToString());
sbuilder.Remove(0, sbuilder.Length);

where sbuilder is an instance of StringBuilder