Directcast与枚举的类型差异(&C)

 Public Enum Fruit
    Red_Apple = 1
    Oranges
    Ripe_Banana
End Enum
Private Sub InitCombosRegular()
    Dim d1 As New Dictionary(Of Int16, String)
    For Each e In [Enum].GetValues(GetType(Fruit))
        d1.Add(CShort(e), Replace(e.ToString, "_", " "))
    Next
    ComboBox1.DataSource = d1.ToList
    ComboBox1.DisplayMember = "Value"
    ComboBox1.ValueMember = "Key"
    ComboBox1.SelectedIndex = 0
End Sub

   'This fails
        Dim combo1 = DirectCast(ComboBox1.SelectedValue, Fruit) ' Fails
        'these both work
        Dim combo2 = DirectCast(CInt(ComboBox1.SelectedValue), Fruit) 'works
        Dim combo3 = CType(ComboBox1.SelectedValue, Fruit) 'works

为什么 CType DirectCast 不使用相同的语法吗?然而,如果我投下 selectedValue 到 int 在我之前

当做