Question

我在VB.net Compact-framework（VS2008）上工作，我使用了一个ComboBox，我希望在SelectedValue更改为新版本之前有一个函数可以获取之前的SelectedValue一个（实际上改变了DisplayMember）。

以下是一个通用示例：

Private Sub ComboBox1_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedValueChanged
    Dim Bool As Boolean
    Bool = MyFunctionClose(ComboBox1.SelectedValueBeforeChange)
    ...
    Bool = MyFunctionOpen(ComboBox1.SelectedValue)
    ...
End Sub

我的问题是：是否有可能抓住这样的ComboBox1.SelectedValueBeforeChange？

Answer 1

只需将SelectedValue存储在事件的变量中：

    Private cb1PrevValue as object = nothing

    Private Sub ComboBox1_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedValueChanged
        Dim Bool As Boolean
        If cb1PrevValue Is Nothing Then
            'cb1PrevValue = DEFAULT_VALUE (Give it a default value for when it is selected the first time)
        End If
        Bool = MyFunctionClose(cb1PrevValue)
        cb1PrevValue = ComboBox1.SelectedValue
        ...
        Bool = MyFunctionOpen(ComboBox1.SelectedValue)
        ...
    End Sub

如何在SelectedValueChanged之前捕获ComboBox中的值

1 个答案: