Visual Basics，将组合框值存储在变量中

Question

我想将组合框值保存在变量中。但是每当我更改 comboBox 值时，值设置为空，并且所选索引显示为"-1"。下面是我的代码。

Private Sub SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim form As CreateEvalForm = New CreateEvalForm //windows Form
Dim str As String = form.ComboBox1.SelectedIndex
MessageBox.Show(str)                            //shows null
Dim openingId As Integer = Val(form.ComboBox1.Text)
End Sub

任何人都可以提出解决方案吗？

Answer 1

Private Sub SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim str As String = ComboBox1.SelectedIndex
MessageBox.Show(str)
Dim openingId As Integer = Val(ComboBox1.Text)
End Sub

这行得通吗？但是，如果要从组合框的选定值中获得值，则应尝试以下操作：

dim openingId as Integer = Val(comboBox1.SelectedValue)

Answer 2

Dim form As CreateEvalForm = New CreateEvalForm //windows Form

使用此行，您将创建一个新表单，因此该新表单上的组合框也将是新的，并且不会有选定的索引。

您可以通过这种方式使用组合框：

Dim str As String = ComboBox1.SelectedIndex

或

Dim str As String = Me.ComboBox1.SelectedIndex