在运行时创建的不同下拉列表不允许选择不同的项目?

Question

我需要在运行时创建许多下拉列表，并为每个下拉列表选择一个不同的项目。 为了避免连续访问数据库，我创建了一个下拉列表，我将克隆下拉列表中的项目复制到该下拉列表中。奇怪的是，创建的所有下拉列表都选择了最后一个下拉列表的项目，我不明白为什么！我不得不插入所选项目的清理["DlistClone.ClearSelection(("]，否则代码会出错。谁能帮我？谢谢

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim MyRow As New TableRow
Dim MyCell As New TableCell
Dim DList As DropDownList
Dim DlistClone As DropDownList
DList = New DropDownList
DList.Items.Add("1")
DList.Items.Add("2")
DList.Items.Add("3")
MyRow = New TableRow
MyCell = New TableCell
DlistClone = New DropDownList
ClonaDList(DList, DlistClone)
DlistClone.ClearSelection()
DlistClone.Items.FindByText("3").Selected = True
MyCell.Controls.Add(DlistClone)
MyRow.Cells.Add(MyCell)
Table1.Rows.Add(MyRow)
MyRow = New TableRow
MyCell = New TableCell
DlistClone = New DropDownList
ClonaDList(DList, DlistClone)
DlistClone.ClearSelection()
DlistClone.Items.FindByText("2").Selected = True
MyCell.Controls.Add(DlistClone)
MyRow.Cells.Add(MyCell)
Table1.Rows.Add(MyRow)
End Sub
Sub ClonaDList(ByVal Origine As DropDownList, ByVal Destinazione As DropDownList)
Dim I As Integer
Dim EleList As ListItem
For I = 0 To Origine.Items.Count - 1
EleList = Origine.Items(I)
Destinazione.Items.Add(EleList)
Next I
End Sub

Answer 1

好的，我自己知道了！ 当我这样做时

EleList

= Origin.Items (I(Destination.Items.Add (EleList(

我在源下拉列表和目标下拉列表之间创建了一个无意的绑定。 要中断绑定，我必须在两个控件之间使用桥梁，在这种情况下，我通过在 2 个连续步骤中设置 2 个属性来使用 Listitem 对象

Sub ClonaDList(ByRef Origine As DropDownList, ByRef Destinazione As DropDownList)
Dim I As Integer
Dim EleList As ListItem
For I = 0 To Origine.Items.Count - 1
EleList = New ListItem
EleList.Text = Origine.Items(I).Text
EleList.Value = Origine.Items(I).Value
Destinazione.Items.Add(EleList)
Next I
End Sub

我说的对吗？