如何获取多选列表框中的最后一个选定项? [英] How to get the last selected item in multiselect ListBox?

问题描述

如何在.Net Forms multiselect ListBox中获取最后选择的项目?显然，如果我在列表框中选择一个项目，然后再选择另一个10，则所选项目是第一个.

How to get the last selected item in a .Net Forms multiselect ListBox? Apparently if I select an item in the listbox and then select another 10 the selected item is the first one.

我想获得我选择/取消选择的最后一个元素.

I would like to obtain the last element that I selected/deselected.

推荐答案

我会采用这种通用方法:

I would take this general approach:

收听SelectedIndexChanged事件，并每次浏览SelectedIndices集合.

Listen for the SelectedIndexChanged event and scan through the SelectedIndices collection every time.

保留所有选定索引的单独列表，追加未包含在列表中的索引，删除已取消选择的索引.

Keep a separate list of all selected indices, appending ones that have not been in the list, removing those that have been de-selected.

单独的列表将包含按时间顺序排列的索引，这些索引由用户选择.最后一个元素始终是最近选择的索引.

The separate list will contain the indexes in the chronological order they were selected by the user. The last element always is the most recently selected index.

// 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);
}

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