如何使用父類中子類的值？ vb.net

Question

我有是令人沮喪的我沒有盡頭的一個問題，我有一個父類覆寫投放功能，並在子類覆蓋功能，如下圖所示：

子類

Public Overrides Sub UpdatePrice(ByVal dblRetailPrice As Double) 
    If dblWholesalePrice < 0 Then 
     MessageBox.Show("Error, amount must be greater than 0.") 
    Else 
     dblRetailPrice = dblWholesalePrice * dblStandardMargin 
    End If 
End Sub 

，並在父類中，我有

Public ReadOnly Property RetailPrice() As Double 
    Get 
     Return dblRetailPrice 
    End Get 
End Property 

Public Overridable Sub UpdatePrice(ByVal dblRetailPrice As Double) 
    If dblWholesalePrice < 0 Then 
     MessageBox.Show("Please input an amount greater than 0,wholesale price has not changed", "error") 
    Else 
     dblRetailPrice = 1.1 * dblWholesalePrice 
    End If 
End Sub 

當我調試，產生的價值，但它並沒有延續到父類ski.RetailPrice（）的，似乎是什麼問題這裏？任何幫助將不勝感激。

Answer 1

您不應該在較高範圍內傳入與具有相同名稱的參數作爲類級變量。局部變量將覆蓋其他的，這意味着這一說法在二傳手：

dblRetailPrice = 1.1 * dblWholesalePrice 

將設置你剛剛過去的，不是你的類級dblWholesalePrice成員變量​​臨時參數的值。

簡單的解決辦法就是通過丟棄無用的類型符號前綴更改參數的名稱：

Public Class MyClass 

    Protected dblRetailPrice As Double 

    Public ReadOnly Property RetailPrice() As Double 
     Get 
      Return dblRetailPrice 
     End Get 
    End Property 

    Public Overridable Sub UpdatePrice(ByVal retailPrice As Double) 

     If dblWholesalePrice < 0 Then 
      MessageBox.Show("Please input an amount greater than 0,wholesale price has not changed", "error") 
     Else 
      dblRetailPrice = 1.1 * dblWholesalePrice 
     End If 
    End Sub 

End Class