如何獲取多選列表框中最後選定的項目？

Question

如何獲取.Net Forms多選列表框中最後選定的項目？顯然，如果我在列表框中選擇一個項目，然後再選擇另一個項目，第一個項目就是第一個。

我想獲得我選擇/取消選擇的最後一個元素。

Answer 1

我想借此一般方法：

收聽SelectedIndexChanged事件並每次掃描SelectedIndices集合。

保留所有選定索引的單獨列表，追加列表中沒有的索引，刪除那些已被取消選擇的索引。

單獨列表將按用戶選擇的時間順序包含索引。最後一個元素始終是最近選擇的索引。

// for the sake of the example, I defined a single List<int> 
List<int> listBox1_selection = new List<int>(); 

private void listBox1_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    TrackSelectionChange((ListBox)sender, listBox1_selection); 
} 

private void TrackSelectionChange(ListBox lb, List<int> selection) 
{ 
    ListBox.SelectedIndexCollection sic = lb.SelectedIndices; 
    foreach (int index in sic) 
     if (!selection.Contains(index)) selection.Add(index); 

    foreach (int index in new List<int>(selection)) 
     if (!sic.Contains(index)) selection.Remove(index); 
} 

Answer 2

不知道我理解的問題，但最後選擇的項目將是最後的SelectedItems陣列中，所以這樣的事情應該工作：

ListItem i = list.SelectedItems[list.SelectedItems.Length-1]; 

Answer 3

試試這個

private void listBox1_MouseUp(object sender, MouseEventArgs e) 
    { 
     int jj = listBox1.IndexFromPoint(e.X, e.Y); 
     object Test = listBox1.Items[jj]; 
     object LatestItemSelected; 
     if(listBox1.SelectedItems.Contains(Test)) 
      LatestItemSelected = Test; 
    } 

顯然LatestItemSelected是多餘的，有強調的是你找到了你的項目。

Answer 4

在下面的代碼列表框使用的鼠標點擊事件：

private void ListBox1_MouseClick(object sender, MouseEventArgs e) 
{ 
    string s = ListBox1.Items[ListBox1.IndexFromPoint(e.Location)].ToString(); 

    MessageBox.Show(s); 
} 

Answer 5

這是這樣，我在VB做了。

當您刷新列表框時，您必須重新維度數組。

Dim SelectedAry(-1) As Integer 

    Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged 
     Dim LastOne As Integer = -1 
     ' First time there no elements in the preserved array 
     If SelectedAry.Length = 0 Then 
       If ListBox1.SelectedIndex <> -1 Then 
        LastOne = 0 
       End If 
     Else 
       'If the SelectedIndices array is larger than the preserved SelectedAry - means that another one had been selected 
       If ListBox1.SelectedIndices.Count >= SelectedAry.Length Then 
        For i = 0 To ListBox1.SelectedIndices.Count - 1 
          'Go through both arrays comparing the values until there is a mismatch 
          'This means that the value in the SelectesIndices is the last one to be added 
          If ListBox1.SelectedIndices(i) <> SelectedAry(i) Then 
           LastOne = i 
           Exit For 
          End If 
        Next 
       End If 
     End If 
     ' Copy the Listbox selectedindices array into the SelectedAry which is preserved for the next selected index change 
     ReDim SelectedAry(ListBox1.SelectedIndices.Count) 
     For i = 0 To ListBox1.SelectedIndices.Count - 1 
       SelectedAry(i) = ListBox1.SelectedIndices(i) 
     Next 
     ' Display the last one added 
     If LastOne >= 0 Then 
       Dim FileName As String = txtFolder.Text & "\" & ListBox1.Items(ListBox1.SelectedIndices(LastOne)).ToString 
       Display_File(FileName) 
     Else 
     End If 
    End Sub 

Answer 6

使用位反射來獲得FocusedIndex的值是列表框的內部屬性，你可以得到的最後一個專注於項目。

int lastSelectedIndex = (int)typeof(ListBox).GetProperty("FocusedIndex",BindingFlags.NonPublic|BindingFlags.Instance).GetValue(myListBox,null); 
SelectedItemType mySelectedItem = myListBox.Items[lastSelectedIndex] as SelectedItemType; 

Answer 7

使用FocusManager.GetFocusedElement（列表框）或Keyboard.FocusedElement返回你選擇的最後一個項目。