属性 selecteditem 对 RadioButtonList 是只读的

Question

当我像这样动态创建单选按钮列表时出现错误Property selecteditem is readonly：

Dim DDL As New DropDownList
Dim RBL As New RadioButtonList
Dim CBL As New CheckBoxList

DDL.ID = "DDL_" & SelectedCategory & "_" & SubAssy & "_" & ProductType
RBL.ID = "RBL_" & SelectedCategory & "_" & SubAssy & "_" & ProductType
CBL.ID = "CBL_" & SelectedCategory & "_" & SubAssy & "_" & ProductType

If ProductType = "General" Or (CategorySelected = "KC 2.1 (retractor without webbing)" And ProductType = "KC2.1" Or ProductType = "Webbing") Or
(CategorySelected = "KC 2.1 Seatbelt)" And ProductType = "KC2.1") Then

    DDL.Visible = False
    RBL.Visible = False
    CBL.Visible = False

    DDL.SelectedItem = True
    RBL.SelectedItem = True
    CBL.SelectedItem = True

End If

在这 3 行代码中：

DDL.SelectedItem = True
RBL.SelectedItem = True
CBL.SelectedItem = True 

显示错误。我必须使用 RadioButtonList 或 DropDownList 或 CheckBoxList 创建一个表，用户在其中选择项目，但我希望某些按钮具有预选值并且不显示。当我阅读所有选择的按钮时，我想要它。

Answer 1

您的问题是您在尝试选择 control 之前使其不可见。

将这些更改为true：

DDL.Visible = False
RBL.Visible = False
CBL.Visible = False

除此之外，您当时只能在control 中选择一个radio button，所以这有点毫无意义：

DDL.SelectedItem = True
RBL.SelectedItem = True
CBL.SelectedItem = True

更新：

Dim DDL As New DropDownList

以上无法勾选

Dim RBL As New RadioButtonList

我相信首先会被检查

我刚刚意识到你试图创建这些controls。在您实际 add 他们之前，您无法检查、取消选中 controls。这个link 可以帮到你