无法删除第二或第三个所选索引

Question

我有3个列表框，当我选择了三件事时，单击“删除”按钮，它删除了第一个列表框中的文本，但是给出一个例外，说值-1对索引无效。这是我当前的代码：

lstBoxOne.Items.RemoveAt(lstBoxOne.SelectedIndex);
lstBoxTwo.Items.RemoveAt(lstBoxTwo.SelectedIndex);
lstBoxThree.Items.RemoveAt(lstBoxThree.SelectedIndex); 

想知道他们是否可以通过单击按钮删除所有三个选定的文本

编辑：我现在已经放满了期望的图像 Full exception

编辑2：这是带有完整代码的示例

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void LstBoxOne_SelectedIndexChanged(object sender, EventArgs e)
        {
            var deleteD = lstBoxOne.SelectedIndex;
            lstBoxTwo.SelectedIndex = deleteD;
            lstBoxThree.SelectedIndex = deleteD;
    }


    private void BtnInsert_Click(object sender, EventArgs e)
    {
        lstBoxOne.Items.Add(this.txtOne.Text);
        lstBoxTwo.Items.Add(this.txtTwo.Text);
        lstBoxThree.Items.Add(this.txtThree.Text);
        this.txtOne.Focus();
        this.txtOne.Clear();
        this.txtTwo.Focus();
        this.txtTwo.Clear();
        this.txtThree.Focus();
        this.txtThree.Clear();
    }

    private void BtnDelete_Click(object sender, EventArgs e)
    {
        lstBoxOne.Items.RemoveAt(lstBoxOne.SelectedIndex);
        lstBoxTwo.Items.RemoveAt(lstBoxTwo.SelectedIndex);
        lstBoxThree.Items.RemoveAt(lstBoxThree.SelectedIndex);


    }
private void LstBoxTwo_SelectedIndexChanged(object sender, EventArgs e)
        {
            var deleteD = lstBoxTwo.SelectedIndex;
            lstBoxOne.SelectedIndex = deleteD;
            lstBoxThree.SelectedIndex = deleteD;
        }

        private void LstBoxThree_SelectedIndexChanged(object sender, EventArgs e)
        {
            var deleteD = lstBoxThree.SelectedIndex;
            lstBoxOne.SelectedIndex = deleteD;
            lstBoxTwo.SelectedIndex = deleteD;
        } 
    }


    }
    }

Answer 1

问题是由于SelectedIndexChanged上的lstBoxOne事件引起的。

在BtnDelete_Click内，当您从lstBoxOne中删除所选项目时，这会导致lstBoxOne.SelectedIndex发生变化。这导致LstBoxOne_SelectedIndexChanged在之前触发，该项目已从lstBoxTwo和lstBoxThree中删除。当LstBoxOne_SelectedIndexChanged完成并返回到BtnDelete_Click时，lstBoxTwo.SelectedIndex和lstBoxThree.SelectedIndex均为-1，并且Exception由于传递{{1}而发生}到-1。

RemoveAt

解决此问题的一种简单方法是在尝试删除任何项目之前存储每个private void LstBoxOne_SelectedIndexChanged(object sender, EventArgs e) { var deleteD = lstBoxOne.SelectedIndex; lstBoxTwo.SelectedIndex = deleteD; lstBoxThree.SelecteIndex = deleteD; } private void DeleteBtn_Click(object sender, EventArgs e) { lstBoxOne.Items.RemoveAt(lstBoxOne.SelectedIndex); //This line triggers the SelectedIndexChanged event on lstBoxOne. // By the time we get back to this function, lstBoxTwo and lstBoxThree have had // their SelectedIndex set to -1. That is what is causing the exception to occur. lstBoxTwo.Items.RemoveAt(lstBoxTwo.SelectedIndex); //Ooops! lstBoxTwo.SelectedIndex was set to -1 in LstBoxOne_SelectedIndexChanged. } 的选定索引。另外，请检查ListBox来保护自己。

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