Question

在我的MergeCollection类中，我有overide InsertItem方法来检查特定情况。然而，当涉及到Items.Any(..行时，它引发了如下异常。

System.ArgumentException: 'At least one object must implement IComparable.'

合并类：

Public Class Merge
        Property Min As Integer
        Property Max As Integer?
        Property Value As Double

        Public Sub New(min As Integer, max As Integer?, value As Integer)
            Me.Min = min
            Me.Max = max
            Me.Value = value
        End Sub
End Class

Public Enum SortCriteria
        MinThenMax
        MaxThenMin
End Enum

一些比较器：

Public Class MergeComparer
        Implements IComparer(Of Merge)  

        Public SortBy As SortCriteria = SortCriteria.MinThenMax

        Public Function Compare(x As Merge, y As Merge) As Integer Implements IComparer(Of Merge).Compare
           'to be implemented
        End Function
End Class

集合类：

Public Class MergeCollection
          Inherits Collection(Of Merge)

        Public SortBy As SortCriteria = SortCriteria.MinThenMax

        Protected Overrides Sub InsertItem(index As Integer, item As Merge)
            if IsNothing(item.Max)
                If Items.Any(Function(myObject) IsNothing(Items.Max)) Then
                    Return
                End If
            End If
            MyBase.InsertItem(index, item)
        End Sub   

        Public Sub Sort()
            Dim allItems = Items.ToArray()

            Array.Sort(allItems)

            For i = 0 To allItems.GetUpperBound(0)
                Items(i) = allItems(i)
            Next
        End Sub

        Public Sub Sort(comparison As Comparison(Of Merge))
            Dim allItems = Items.ToArray()

            Array.Sort(allItems, comparison)

            For i = 0 To allItems.GetUpperBound(0)
                Items(i) = allItems(i)
            Next
        End Sub

        Public Sub Sort(comparer As IComparer(Of Merge))
            Dim allItems = Items.ToArray()

            Array.Sort(allItems, comparer)

            For i = 0 To allItems.GetUpperBound(0)
                Items(i) = allItems(i)
            Next
        End Sub

End Class

Answer 1

代码要求输入Items.Max。要找到最大值，它必须将各项相互比较。

Public Class Merge
    Implements IComparable(Of Merge)

    Property Min As Integer
    Property Max As Integer?
    Property Value As Double

    Public Sub New()
        ' empty constructor
    End Sub

    Public Sub New(min As Integer, max As Integer?, value As Integer)
        Me.Min = min
        Me.Max = max
        Me.Value = value
    End Sub

    Public Overloads Function CompareTo(other As Merge) As Integer Implements IComparable(Of Merge).CompareTo

        If other Is Nothing Then Return 1

        ' Could use
        ' Return (Me.Value).CompareTo(other.Value)
        ' instead of the following code...
        If Me.Value > other.Value Then Return 1
        If Me.Value = other.Value Then Return 0

        Return -1

    End Function

End Class

我想您需要一个不同的比较标准。

System.ArgumentException：至少一个对象必须实现IComparable

1 个答案: