Question

我正在尝试在VB.net 2008中搜索listview。它适用于小列表，但是当列表很大（大约25000行）时，如果我搜索多个项目，则表示索引无效。显然我理解的是，它试图删除索引不存在。但我无法弄清楚到底出了什么问题。有人可以帮忙吗？

PS：当它正在搜索整个列表视图时，我正在递增index = index+5因为我希望接下来的5行也处于选择状态。

这是代码：

Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp
    If (e.KeyCode = Keys.PageDown) Then
            'ListView1.Items.Clear()
            Dim s As String
            Dim index As Integer
            Dim item As String


            ListView1.BeginUpdate()

            Try
                ' keep track of the "non-searched items" '
                Dim indicesToRemove As New List(Of Integer)

                ListView1.SelectedIndices.Clear()
                If TextBox1.Text.Length > 0 Then
                    Dim lstOfStrings() As String = TextBox1.Text.Split(","c)

                    For Each s In lstOfStrings

                        For index = 0 To ListView1.Items.Count - 1

                            If s.Trim() <> "" Then
                                item = ListView1.Items(index).ToString()

If item.IndexOf(s, StringComparison.CurrentCultureIgnoreCase) >= 0 Then

                                    ListView1.SelectedIndices.Add(index)
                                    index = index + 5
                                    'ListView1.SelectedIndices.Add(index)


                                Else
                                    ' this item was not searched for; we will remove it '
                                    indicesToRemove.Add(index)
                                End If
                            End If

                        Next

                        ' go backwards to avoid problems with indices being shifted '
                        For i As Integer = indicesToRemove.Count - 1 To 0 Step -1
                            Dim indexToRemove As Integer = indicesToRemove(i)
                    ListView1.Items.RemoveAt(indexToRemove) ' blowing on this line
                        Next

                    Next s

                End If
            Finally
                ListView1.EndUpdate()
            End Try
End Sub

感谢。

Answer 1

IMO，在这段代码中有很多东西需要修复......但是一个可以解决你的问题的简单修复是这样的：不是抓住要删除的列表项索引，而是保留一个列表项的数组他们自己，然后只需在每个方法上调用Remove方法。这样你甚至不需要处理索引和订购。

编辑：我认为For Each s In lstOfStrings应该在列表项迭代中嵌套。这可能是问题的一个重要部分。

编辑2：您可能希望让我们了解您尝试使用此代码完成的任务，因为其中有很多内容没有多大意义。

编辑3：我使用ListView，TextBox和Button创建了一个测试项目，并在Form_Load中向ListView添加了一些随机项。这个逻辑对我来说仍然没有100％的意义，但我没有遇到任何崩溃。

编辑4：简化代码。删除了index = index + 5内容。

编辑5：返回其他代码。重新实现了奇怪的索引选择。

编辑6：最后？

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click If TextBox1.Text.Trim().Length = 0 Then Exit Sub ' keep track of the "non-searched items" ' Dim itemsToRemove As New List(Of ListViewItem) ListView1.BeginUpdate() ListView1.SelectedIndices.Clear() If TextBox1.Text.Length > 0 Then Dim lstOfStrings() As String = TextBox1.Text.Split(","c) For index As Integer = 0 To ListView1.Items.Count - 1 For Each s As String In lstOfStrings Dim realS As String = s.Trim() If realS "" Then Dim item As ListViewItem = ListView1.Items(index) If item.Text.IndexOf(realS, StringComparison.CurrentCultureIgnoreCase) >= 0 Then Dim i As Integer = 1 While (i + index < ListView1.Items.Count) And (i <= 5) ListView1.SelectedIndices.Add(i + index) i = i + 1 End While index = index + 5 Exit For Else ' this item was not searched for; we will remove it ' itemsToRemove.Add(item) End If End If Next s Next index For Each i As ListViewItem In itemsToRemove ListView1.Items.Remove(i) Next i End If ListView1.EndUpdate() End Sub

Answer 2

试试这个。像Jon说的那样，使用listitem本身而不是索引要容易得多。使用for each item循环，您可以随时删除它们。顺便说一下，我推荐某种消息或断点以及try块的结束，特别是那个很大的。

Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp

  If (e.KeyCode = Keys.PageDown) Then
    'ListView1.Items.Clear()
    Dim s As String
    Dim item As ListViewItem
    Dim found As Boolean

    ListView1.BeginUpdate()

    Try
        ' keep track of the "non-searched items" '
        Dim indicesToRemove As New List(Of Integer)

        ListView1.SelectedIndices.Clear()
        If TextBox1.Text.Length > 0 Then
          Dim lstOfStrings() As String = TextBox1.Text.Split(","c)
          For Each item In ListView1.Items
            found = False
            For Each s In lstOfStrings
              If String.Compare(s, item.Text, True) = 0 Then
                found = True
                Exit For
              End If
            Next s
          If Not found Then ListView1.Items.Remove(item)
          Next item
        End If

    Catch ex As Exception
      MsgBox(ex.Message)
    Finally
      ListView1.EndUpdate()
    End Try
  End If
End Sub

从ListView中删除项目

2 个答案: