Private Sub FindStringButton_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles FindStringButton.Click
    Dim index As Integer = ListBox1.FindString(TextBox1.Text)
    If (index < 0) Then
        MessageBox.Show("找不到你要的選項.")
        TextBox1.Text = String.Empty
    Else
        ListBox1.SelectedIndex = index
    End If
End Sub