这羔羊是怎么回事?

Dim count As Func(Of Integer, Boolean) = Function(x As Integer) x = 1

If (count(GetSelectedCount())) Then
    'Proceed
Else
    MessageBox.Show("You can only select one item at a time.", "Multiple items selected", MessageBoxButtons.OK)
End If

GetSelectedCount返回在网格中标记的项目数。未选择任何内容时返回0。仅当选择了1个项时,lambda才应返回true。只有选择了1个项目时,才应运行消息框。即使没有选择任何项目,我也会得到消息框。

解决方案~决定放弃lambda去上老派学校

Select Case GetSelectedCount()
    Case 1

    Case Is > 1
        MessageBox.Show("You can only select one item at a time.", "Multiple Selection", MessageBoxButtons.OK)
    Case Else
        MessageBox.Show("You have no items selected.", "No Selection", MessageBoxButtons.OK)

End Select