从数据网格视图中删除多行后索引超出范围？C＃

Question

我使用 anArrayList进行二分搜索。datagridview 的行被添加到ArryList。当我从 datagridview 中删除一行时，它几乎完美地工作。问题是当我从顶部或底部和中间的 datagridview 中删除许多行时，它给了我一个错误。ArrayList从ArrayList（datagridview）中删除一行后，如何刷新或更新？

错误：

'索引超出范围。必须是非负的并且小于集合的大小。参数名称：索引'

我将行复制到 ArrayList 的代码：

我将此代码放入按钮MouseEnter事件中，因此在单击按钮进行搜索之前，它将所有内容复制到ArrayList.

foreach (var row in dataGridView2.Rows.Cast<DataGridViewRow>())

{

   ArrayList[row.Index] = row.Cells[0].Value.ToString().Trim();

}

我对所选行的删除代码：

foreach (DataGridViewRow item in this.dataGridView2.SelectedRows)

{

    dataGridView2.Rows.RemoveAt(item.Index);

    return;

}

我在 winform 中进行二分搜索的代码：

int index = this.ArrayList.BinarySearch(textBoxBinarySearch.Text);

if (index > -1)

{

    dataGridView2.SelectionMode = DataGridViewSelectionMode.RowHeaderSelect;

    dataGridView2.Rows[index].Selected = true;

    dataGridView2.CurrentCell = dataGridView2.Rows[index].Cells[0];

    MessageBox.Show("Index is equal to: " + index, "Binary Search");

}

错误发生在：

dataGridView2.Rows[index].Selected = true;

打开 csv 后，二进制搜索完美运行！

Answer 1

问题似乎是您只是从 DataGridView 中删除项目，而不是从 ArrayList 中删除项目，然后对 DataGridView 使用 arraylist 搜索索引。因此，如果您从 DataGridView 中删除最后一个项目，它仍然存在于 ArrayList 中，因此如果您匹配该项目并尝试使用 DataGridView 中的索引，您将获得索引超出范围异常。如果您在arraylist 和datagridview 中有10 个项目，然后从datagridview 中删除2 个，那么您现在在arraylist 中有10 个项目，在datagridview 中有8 个项目。如果您收到数组列表（8 或 9）中最后 2 个项目中的任何一个的索引并尝试访问 datagridview 中这些索引中的项目，它将引发异常。尝试使用数据绑定，然后仅对 ArrayList 进行操作。dataGridView2.DataSource = ArrayList;此外，如果您要循环删除项目的列表，请向后执行。从最后一个项目开始，然后回到起点：for(int i = dataGridView2.SelectedRows.Count - 1 ; i >= 0 ; i--){&nbsp; &nbsp; dataGridView2.Rows.RemoveAt(dataGridView2.SelectedRows[i].Index);}执行 foreach 会导致枚举器抛出异常，因为列表已从一次传递更改为下一次传递。

Answer 2

我已经提出了一种快速的方法：public partial class Form1 : Form{&nbsp; &nbsp; public Form1()&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; InitializeComponent();&nbsp; &nbsp; &nbsp; &nbsp; PopulateGrid();&nbsp; &nbsp; }&nbsp; &nbsp; private ArrayList myList = new ArrayList();&nbsp; &nbsp; private List<Student> students = new List<Student>();&nbsp; &nbsp; private void PopulateGrid()&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; students = new List<Student>&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "aa"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "bb"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "cc"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "cc"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "cc"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "ee"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "ff"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "ff"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "gg"},&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; new Student {Lastname = "gg"},&nbsp; &nbsp; &nbsp; &nbsp; };&nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.DataSource = students;&nbsp; &nbsp; &nbsp; &nbsp; myList = new ArrayList(students.Select(x => x.Lastname).ToList());&nbsp; &nbsp; }&nbsp; &nbsp; public class Student&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; public string Lastname { get; set; }&nbsp; &nbsp; }&nbsp; &nbsp; private void btnSearch_Click(object sender, EventArgs e)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; var index = myList.BinarySearch(textBoxBinarySearch.Text);&nbsp; &nbsp; &nbsp; &nbsp; if(index > -1)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.SelectionMode = DataGridViewSelectionMode.RowHeaderSelect;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.Rows[index].Selected = true;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.CurrentCell = dataGridView2.Rows[index].Cells[0];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; MessageBox.Show("Index is equal to: " + index, "Binary Search");&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; private void btnDelete_Click(object sender, EventArgs e)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; if (dataGridView2.SelectedRows.Count > 0)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; var selected = dataGridView2.SelectedRows[0];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; students.RemoveAt(selected.Index);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.DataSource = null;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; dataGridView2.DataSource = students;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; myList = new ArrayList(students.Select(x => x.Lastname).ToList());&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}但我建议避免使用，ArrayList因为它不是强类型。使用List<T>来代替。我想使用 ArrayList 的原因是BinarySearch方法。

Answer 3

我使用 anArrayList进行二分搜索。datagridview 的行被添加到ArryList。当我从 datagridview 中删除一行时，它几乎完美地工作。问题是当我从顶部或底部和中间的 datagridview 中删除许多行时，它给了我一个错误。ArrayList 从ArrayList（datagridview）中删除一行后，如何刷新或更新？解决方案：当我打开两次 csv 文件时，二进制搜索运行良好，但第三次却没有，因为我不仅必须ArrayList使用ArrayList.Clear();datagridview清除我的数据。然后我可以将 datagridview 行复制到空的ArrayList.dataGridView2.Rows.Clear();ArryList.Clear();然后->我将行复制到 ArrayList 的代码：我将此代码放入按钮MouseEnter事件中，因此在单击按钮进行搜索之前，它将所有内容复制到ArrayList.foreach (var row in dataGridView2.Rows.Cast<DataGridViewRow>()){&nbsp; &nbsp;ArrayList[row.Index] = row.Cells[0].Value.ToString().Trim();}我对所选行的删除代码：for (int i = dataGridView2.SelectedRows.Count - 1; i >= 0; i--){&nbsp;&nbsp; &nbsp; &nbsp; dataGridView2.Rows.RemoveAt(dataGridView2.SelectedRows[i].Index);&nbsp; &nbsp; &nbsp; ListOfPeople.RemoveAt(i);}我在 winform 中进行二分搜索的代码：int index = this.ArrayList.BinarySearch(textBoxBinarySearch.Text);if (index > -1){&nbsp; &nbsp; dataGridView2.SelectionMode = DataGridViewSelectionMode.RowHeaderSelect;&nbsp; &nbsp; dataGridView2.Rows[index].Selected = true;&nbsp; &nbsp; dataGridView2.CurrentCell = dataGridView2.Rows[index].Cells[0];&nbsp; &nbsp; MessageBox.Show("Index is equal to: " + index, "Binary Search");}感谢您阅读全文！