当我没有尝试施放任何东西时出现错误(Casting error when I'm not trying to cast anything)

当我没有尝试施放任何东西时出现错误(Casting error when I'm not trying to cast anything)

我正试图让一个简单的纸牌游戏工作......我得到一个“不可能施放”的错误......但我不是想要施展任何东西......我有点混淆为什么我收到这个错误。 下面是我使用的3个对象的快速摘要。

Public Class Holder inherits Panel end class Public Class Card inherits PictureBox end class public Class Location Public Property X as integer Public Property Y as integer end class Public Class Board inherits Form Public Property Tile as Dictionnary(of Location, Holder) Public sub PlayCard(card as Card, loc as Location) Tile(loc).Controls.Add(card) end sub end Class

我得到一个InvalidCastException：

无法在类型'卡'中投射对象类型'持有人'。

我已经进行了三次检查，以确保它真的是一张卡片作为参数传递给PlayCard sub ....我不知道该怎么做...

有什么建议么 ？

编辑：

Private Sub TEST() Handles Board.Load Dim c = New Card Dim p1 As Location p1 = New Location(2, 1) c.Image = My.Resources.Tree Me.Play(c, p1) End Sub

I'm trying to get a simple card game to work ... and I'm getting an "Impossible to cast " error ... but I'm not trying to cast anything ... I'm a little confuse about why I get this error. Heres a quick summary of the 3 object I use.

Public Class Holder inherits Panel end class Public Class Card inherits PictureBox end class public Class Location Public Property X as integer Public Property Y as integer end class Public Class Board inherits Form Public Property Tile as Dictionnary(of Location, Holder) Public sub PlayCard(card as Card, loc as Location) Tile(loc).Controls.Add(card) end sub end Class

and I get an InvalidCastException:

Impossible to cast objet type 'Holder' in Type 'Card'.

I've triple check to make sure its really a card thats being pass as a parameter to the PlayCard sub .... and I get no idea what to do from here ...

any suggestions ?

EDIT :

Private Sub TEST() Handles Board.Load Dim c = New Card Dim p1 As Location p1 = New Location(2, 1) c.Image = My.Resources.Tree Me.Play(c, p1) End Sub

最满意答案

Haaaaaaaaaaaaaaa我发现它...我的一个朋友告诉我要注意事件，他是对的。

我正在使用Handles Holder.ControlAdded的事件

甚至是Holder本身的发送者，我假设它是添加的控件，因此InvalidCastError。

在control.add（）行而不是在事件内部引发错误，这导致我的困惑。

Haaaaaaaaaaaaaaa I find it ... a friend of mine told me to watch out for events and he was right.

I'm using an event that Handles Holder.ControlAdded

The sender of that even is the Holder itself, I had assume it was the control added, hence the InvalidCastError.

the error get raised on the control.add() line instead of inside the event, which leads to my confusion.