ASP.NET(VB) 列表框未将所有选定项目移动到其他列表框

Question

DivisionListBox 用于 select SitesListbox 中的值，如下所示：当您 select DivisionListBox 中的一个项目时，它将 select SitesListbox 上匹配相同的所有项目值。

SiteListbox 值被 selected 后，我使用 SiteButton 将所有 selected 值成功移动到空的 StoreslistBox。

当我在 SiteListbox 或 StoreslistBox 上手动 select 多个项目并按 SiteButton 或 StoreButton 在列表框之间移动项目时，我的问题就出现了。它要么一次移动一个项目，要么移动一些 selected 项目，但它永远不会移动所有 selected 项目（可以通过标签跟踪）。

是什么导致了这个问题，可能的解决方案是什么？

我的代码

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    DivisionSelection()

End Sub

Private Sub DivisionSelection()

    If DivisionListBox.SelectedValue IsNot Nothing Then
        SitesListBox.SelectionMode = ListSelectionMode.Multiple
        For Each item As ListItem In SitesListBox.Items
            If item.Value = DivisionListBox.SelectedValue Then
                item.Selected = True
            End If
        Next
    End If

    Dim x As Integer = 0
    Dim Siteitem As ListItem
    For Each Siteitem In SitesListBox.Items
        If Siteitem.Selected Then
            x += 1
            Label1.Text = x
        End If
    Next
End Sub

Protected Sub SiteButton_Click(sender As Object, e As EventArgs) Handles SiteButton.Click

    StoresListBox.SelectionMode = ListSelectionMode.Multiple
    While SitesListBox.SelectedItem IsNot Nothing
        StoresListBox.Items.Add(SitesListBox.SelectedItem)
        SitesListBox.Items.Remove(SitesListBox.SelectedItem)
    End While

    'counts the selected items
    Dim x As Integer = 0
    Dim Siteitem As ListItem
    For Each Siteitem In SitesListBox.Items
        If Siteitem.Selected Then
            x += 1
            Label1.Text = x
        End If
    Next
End Sub

Protected Sub StoreButton_Click(sender As Object, e As EventArgs) Handles StoreButton.Click

    StoresListBox.SelectionMode = ListSelectionMode.Multiple
    While StoresListBox.SelectedItem IsNot Nothing
        SitesListBox.Items.Add(StoresListBox.SelectedItem)
        StoresListBox.Items.Remove(StoresListBox.SelectedItem)
    End While

    'counts the selected items
    Dim x As Integer = 0
    Dim Storeitem As ListItem
    For Each Storeitem In SitesListBox.Items
        If Storeitem.Selected Then
            x += 1
            Label2.Text = x
        End If
    Next

End Sub

Answer 1

我将所选项目添加到列表；然后循环遍历列表以进行添加和删除。当一个集合或索引在循环中被弄乱时，它可能会产生意想不到的结果。

Protected Sub Button1_Click(ByVal sender As Object, e As System.EventArgs) Handles Button1.Click
    Dim lstItems As New List(Of ListItem)
    For Each item As ListItem In ListBox1.Items
        If item.Selected Then
            lstItems.Add(item)
        End If
    Next
    'It wasn't clear if you wanted the items to remain selected after moving.
    ListBox1.ClearSelection()
    Debug.Print(lstItems.Count.ToString)
    For Each item As ListItem In lstItems
        ListBox2.Items.Add(item)
        ListBox1.Items.Remove(item)
    Next
End Sub

ASP.NET(VB) 列表框未将所有选定项目移动到其他列表框

ASP.NET(VB) Listboxes are not moving all the selected items to other Listboxes

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