Question

当我点击一行以删除其内容并将上下行的内容合并为一行时，我的listview会间歇性地收到错误。当我在程序的另一部分中使用代码时它可以工作，但由于某种原因，它在下面的代码列表中给出了错误。有没有办法从列表视图中所选行的上下行获取代码？

             if ( iIndex > 0 && iIndex +1 < listView1.Items.Count)
            {///get my error on the row below for content one 'InvalidArgument=Value of '-1' is not valid for 'index'.'
                string content1 = listView1.Items[listView1.SelectedIndices[-1]].SubItems[0].Text;
                string content2 = listView1.Items[listView1.SelectedIndices[1]].SubItems[0].Text;
                string NumCellAbove = listView1.Items[listView1.SelectedIndices[0] - 1].SubItems[1].Text;
                string NumCellBelow = listView1.Items[listView1.SelectedIndices[0] + 1].SubItems[1].Text;
                int TotalFsCt1 = int.Parse(content);
                int TotalFsCtAbove1 = int.Parse(NumCellAbove);
                int TotalFsCtBelow1 = int.Parse(NumCellBelow);
                int TotalFsCt= TotalFsCt1 + TotalFsCtAbove1 + TotalFsCtBelow1;
                int TotalFsCtAbove = TotalFsCt1 + TotalFsCtAbove1;
                int TotalFsCtBelow = TotalFsCt1 + TotalFsCtBelow1;
                if (content1 != "Free Space" && content2 != "Free Space")
                {
                    listView1.Items.Remove(listView1.FocusedItem);
                    ListViewItem item3 = new ListViewItem("Free Space");
                    item3.BackColor = Color.Yellow;
                    item3.UseItemStyleForSubItems = false;
                    item3.SubItems.Add(new ListViewItem.ListViewSubItem(item3,
                    content, Color.Black, Color.Yellow, item3.Font));
                    item3.SubItems.Add(new ListViewItem.ListViewSubItem(item3,
                    "        0", Color.Black, Color.White, item3.Font));
                    listView1.Items.Insert(iIndex, item3);
                    totalMBct1 += newTotalct;
                    SetHeight(listView1, 256 / listView1.Items.Count);
                    if (button1.Enabled == false)
                    {
                        MessageBox.Show("Enabling button again memory less then full!");
                        button1.Enabled = true;
                    }
                }
       }


    ////Yet this code below this line works fine and never gives the error
                if (iIndex > 0 && iIndex < listView1.Items.Count)
            {
                string content1 = listView1.Items[listView1.SelectedIndices[0]].SubItems[0].Text;
                string content2 = listView1.Items[listView1.SelectedIndices[0] - 1].SubItems[0].Text;
                string NumCellAbove = listView1.Items[listView1.SelectedIndices[0] -1].SubItems[1].Text;
                int TotalFsCt1 = int.Parse(content);
                int TotalFsCtAbove1 = int.Parse(NumCellAbove);
                int TotalFsCtAbove = TotalFsCt1 + TotalFsCtAbove1;
                if (content1 != "Free Space" && content2 == "Free Space")
                {
                    string Above = TotalFsCtAbove.ToString();
                    listView1.Items[iIndex -1].Remove();
                    listView1.Items.Remove(listView1.FocusedItem);
                    ListViewItem item3 = new ListViewItem("Free Space");
                    item3.BackColor = Color.Yellow;
                    item3.UseItemStyleForSubItems = false;
                    item3.SubItems.Add(new ListViewItem.ListViewSubItem(item3,
                    Above, Color.Black, Color.Yellow, item3.Font));
                    item3.SubItems.Add(new ListViewItem.ListViewSubItem(item3,
                    "        0", Color.Black, Color.White, item3.Font));
                    listView1.Items.Insert(iIndex-1, item3);
                    totalMBct1 += newTotalct;
                    SetHeight(listView1, 256 / listView1.Items.Count);
                    if (button1.Enabled == false)
                    {
                        MessageBox.Show("Enabling button again memory less then full!");
                        button1.Enabled = true;
                    }
                }

Answer 1

您无法从SelectedIndices获取位置-1的元素，因为位置-1处没有项目，因此您将获得异常。您可能想要做的是将项目放在selectedIndex的位置 - 1.因此，您必须做类似的事情：

string content1 = listView1.Items[listView1.SelectedIndices[0]-1].SubItems[0].Text;
string content2 = listView1.Items[listView1.SelectedIndices[0]+1].SubItems[0].Text;

但是，我建议首先检查一个项目是否实际被选中：

if (listView1.SelectedIndices.Count == 0)
    return;

你应该检查你的清单中是否包含足够的元素：

if (listView1.Items.Count == 0 || listView2.Items.Count < 2)
    return;

我不太明白为什么你在第二个例子中使用了正确的尝试，但是在第一个例子中没有。

如何在列表视图中获取所选行上方和下方行的内容？

1 个答案: