vb.net – 如何创建不会导致无限循环的工厂对象

2019年7月29日 218次阅读

每当我尝试创建一个新的CD对象时,我都会遇到堆栈溢出.我想将一个参数传递给mediaFactory,以便确定创建了什么类型的媒体.任何人都可以指出为什么我这样做时可能遇到问题“Dim media As CD = New CD()”

谢谢

Public MustInherit Class MediaFactory
Inherits MediaContext
Implements IMedia

Public Sub New(ByVal typeId As Integer)
    MyBase.new()
    _mediaTypeId = typeId
End Sub

Private _mediaTypeId As Integer
Public Property mediaTypeId() As Integer Implements IMedia.mediaTypeId
    Get
        Return _mediaTypeId
    End Get
    Set(ByVal value As Integer)
        _mediaTypeId = value
    End Set
End Property

End Class


Public Class CD
Inherits MediaFactory 
Implements IMedia 

Public Sub New() 
    MyBase.New(1) 
End Sub 

Public Sub New(ByVal name As String) 
    MyBase.New(1) 
    MyBase.title = name 
End Sub 

End Class


Public Class MediaContext

Private Shared _strategies As New Dictionary(Of MediaEnum, IMedia)()

Public Sub New()
    _strategies.Add(MediaEnum.CD, New CD())

End Sub

Public Sub New(ByVal name As String)
    _title = name
End Sub

Private _title As String
Public Property title() As String
    Get
        Return _title
    End Get
    Set(ByVal value As String)
        _title = value
    End Set
End Property

End Class

最佳答案 在无限递归的情况下发生堆栈溢出.当你有方法调用时会发生这种情况：

Public Sub B()
 A()
End Sub

Public Sub A()
 B()
End Sub

然后调用A()或B().调用堆栈的大小(跟踪当前正在运行的子站点,以及调用它的子站点,依此类推到程序的主站点)会无限增长,直到达到可用空间的限制. (它看起来像A> B> A> B> A> B ……等)

在你的情况下,似乎你的New()方法调用New(1),它反过来调用MediaFactory的New(整数),调用.new(),它调用你工厂的New()…希望你得到的图片.

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