如何在SelectedIndexChanged事件中获取GetItemCheckState

Question

我正在尝试制作一个checkBoxList，每当我检查/取消选中一个项目时它会向下/向上排序，这样未经检查的项目将位于顶部，并且检查将位于底部。为此我创建了一个事件checkedListBox1_SelectedIndexChanged。我的问题是如何检查选择它，我得到一个例外。我假设这是因为它正在改变，而我正在检查当前状态是什么

这是我的代码：

private void checkedListBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        var items = checkedListBox1.Items;
        List<string> checkedList = new List<string>();
        List<string> uncheckedList = new List<string>();
        int selected = checkedListBox1.SelectedIndex;
        string state = checkedListBox1.GetItemCheckState(checkedListBox1.Items.IndexOf(selected)).ToString();
        //error: An unhandled exception of type 'System.ArgumentOutOfRangeException' occurred in System.Windows.Forms.dll
        //Additional information: InvalidArgument = Value of '-1' is not valid for 'index'.
        if (state == "Checked")
            uncheckedList.Add(selected.ToString());
        else
            checkedList.Add(selected.ToString());

        foreach (var item in items)
        {
            int index = checkedListBox1.Items.IndexOf(item);
            if (index != selected)
            {
                state = checkedListBox1.GetItemCheckState(checkedListBox1.Items.IndexOf(item)).ToString();
                if (state == "Checked")
                    checkedList.Add(item.ToString());
                else
                    uncheckedList.Add(item.ToString());
            }
        }
    }