列表（类）中元素的深度复制

Question

晚上好。

我正在尝试对列表中的某些元素进行深度复制，但我发现它非常难以做到。我正在尝试很多新概念，如果以下代码看起来很奇怪，请耐心等待...

我有以下列表：

accountList as List(Of Account)
accountsInArea as New List(Of Account)
result as New List(Of Account)

其中每个元素的类型都是我自己定义的 Class：

Public Class Account

Enum AddingType
    income
    expenditure
End Enum
Enum AreaType
    high
    mid
    low
End Enum

Property Area() As AreaType
Property Group() As String
Property AccountNumber() As Integer
Property AccountDescription() As String
Property IncomeExpenditure() As AddingType
Public Property MonthlyValues As New Dictionary(Of Integer, Decimal)
End Class

我需要找到accountList 的某些 项并将值 复制到一个新列表：accountsInArea。目前，我使用了以下方法：

accountsInArea = accountList.FindAll(Function(acc) acc.Area = area)

但是，这会生成 Lambda 表达式生成的那些项目的 reference 副本（不是吗？）。如果我在浏览 SO 和 MSDN 时理解正确，我需要的是元素的深拷贝。

我希望accountsInArea 拥有.FindAll 生产的所有项目的副本，包括（尤其是）MonthlyValuesDictionary 中的项目。

我试过了：

accountsInArea = accountList.Select(accountList.FindAll(Function(acc) acc.Area = area))

还有：

For Each account In accountList.FindAll(Function(acc) acc.Area = area)
    accountsInArea.Add(account)
Next

最后添加到类中：

Implements ICloneable

Public Function Clone() As Object Implements System.ICloneable.Clone
    Return Me.MemberwiseClone
End Function

并在方法内部使用：

accountsInArea = accountList.FindAll(Function(acc) acc.Area = area)
    result = accountsInArea.Select(Function(acc) acc.Clone()).Cast(Of Account).ToList

非常感谢您的帮助。

Answer 1

只需在您的类中实现 ICloneable，然后

Dim accountsInArea As List(Of Account) = accountList.Where(Function(x) x.Area = Account.AreaType.high).Select(Function(y) y.clone).Cast(Of Account)().ToList

这里是你前任的完整代码

Sub AccountListProg
    Dim accountList As New List(Of Account) From {New Account With {.Area = Account.AreaType.high, .AccountNumber = 1}, _
                                                   New Account With {.Area = Account.AreaType.high, .AccountNumber = 2}, _
                                                   New Account With {.Area = Account.AreaType.low, .AccountNumber = 3}, _
                                                   New Account With {.Area = Account.AreaType.mid, .AccountNumber = 4}}

    Dim accountsInArea As List(Of Account) = accountList.Where(Function(x) x.Area = Account.AreaType.high).Select(Function(y) y.clone).Cast(Of Account)().ToList
End Sub

Public Class Account
    Implements ICloneable
    Public Function Clone() As Object Implements ICloneable.Clone
        Return New Account With {.AccountDescription = AccountDescription, _
                             .AccountNumber = AccountNumber, _
                             .Area = Area, _
                             .Group = Group, _
                             .IncomeExpenditure = AddingType.income, _
                             .MonthlyValues = MonthlyValues}
    End Function
    Enum AddingType
        income
        expenditure
    End Enum
    Enum AreaType
        high
        mid
        low
    End Enum

    Property Area() As AreaType
    Property Group() As String
    Property AccountNumber() As Integer
    Property AccountDescription() As String
    Property IncomeExpenditure() As AddingType
    Public Property MonthlyValues As New Dictionary(Of Integer, Decimal)
End Class

Answer 2

经过一番修改后，我找到了解决方案。虽然我确信有更优雅的东西，但我会在这里发布以防万一有人急需：

我最终在方法中使用了以下代码：

Dim accountsInArea as New List(Of Account)

For Each account In accountList.FindAll(Function(acc) acc.Area = area)
    Dim a As New Account
    With a
        .Area = account.Area
        .AccountDescription = account.AccountDescription
        .Group = account.Group
        .IncomeExpenditure = account.IncomeExpenditure
        .AccountNumber = account.AccountNumber
        .MonthlyValues = New Dictionary(Of Integer, Decimal)
    End With
    For Each val In account.MonthlyValues
        Dim k As Integer = v.Key
        Dim v As Decimal = v.Value
        a.MonthlyValues.Add(k, v)
    Next
    accountsInArea.Add(a)
Next

因此，如果有人知道一种不太复杂的方法（可能涉及我在问题中提到的一种方法），那就太棒了。

还是谢谢。