Question

如何在cSystemCatalog类中比较两个通用列表（cSystem）？我想知道如果其中一个列表包含更多或更少的类对象，我还想比较_systemKey和_systemName

Public Class cSystemCatalog
    Private _systems As List(Of cSystem)

Public Class cSystem
    Private _systemKey As Int32
    Private _systemName As String

Answer 1

If _systems1.Count > _systems2.Count Then

Answer 2

If _systems1.Count = _systems2.Count AndAlso _
_systems1.All(Function(s1) _systems2.Any(Function(s2) _
s2._systemKey = s1._systemKey AndAlso s2._systemName = s1._systemName)) Then

如果您可以使用LINQ：

Imports System.LINQ

Answer 3

我通过实现IEquatable接口找到了解决方案。

Public Class cSystem Implements IEquatable(Of cSystem)
     Private _systemKey As Int32
     Private _systemName As String

Public Overloads Function Equals(ByVal other As cSystem) As Boolean Implements IEquatable(Of cSystem).Equals
    If other Is Nothing Then Return False
    If _systemKey = other.SystemKey AndAlso _systemName = other.SystemName Then
        Return True
    Else
        Return False
    End If
End Function

Public Overrides Function Equals(ByVal obj As Object) As Boolean
    If obj Is Nothing Then Return MyBase.Equals(obj)

    If Not TypeOf obj Is cSystemThen
        Throw New InvalidCastException("The 'obj' argument is not a cSystemobject.")
    Else
        Return Equals(DirectCast(obj, cSystem))
    End If
End Function

Public Shared Operator =(ByVal system1 As cSystem, ByVal system2 As cSystem) As Boolean
    Return system1.Equals(system2)
End Operator

Public Shared Operator <>(ByVal system1 As cSystem, ByVal system2 As cSystem) As Boolean
    Return Not system1.Equals(system2)
End Operator

然后我使用列表中的contains方法来比较包含cSystem类对象的通用列表：

Dim valuesHasBeenChanged As Boolean
If objSystemCatalog.Systems.Count = objOldSystemCatalog.Systems.Count Then
    For Each system As cSystem In objSystemCatalog.Systems
        If objOldSystemCatalog.Systems.Contains(system) = False Then
            valuesHasBeenChanged = True
        End If
    Next
ElseIf objSystemCatalog.Systems.Count > objOldSystemCatalog.Systems.Count Then
    valuesHasBeenChanged = True
ElseIf objSystemCatalog.Systems.Count < objOldSystemCatalog.Systems.Count Then
    valuesHasBeenChanged = True
End If

比较两个包含类对象的通用列表

3 个答案: