如何为自己的类定义'='？

Question

我创造了这样一个类：

Public Class WorkDay    

    <JsonProperty("start")> 
    Public Property starttime As String = Nothing 
    <JsonProperty("end")> 
    Public Property endtime As String = Nothing 
    Public Property breaks As New List(Of Break) 

End Class 

现在我需要比较这个类的一个对象，比如这个：

Dim working_plan = JsonConvert.DeserializeObject(Of Dictionary(Of String, WorkDay))(wp) 
Dim DayNames = {"monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"} 
Dim this_day = working_plan(day) 

If this_day = Nothing Then 
    ... 

现在this_day是WorkDay类的对象，所以当我尝试比较没什么，我得到：

运算符=未定义为WorkDay类型。

我应该在我自己的类中定义运算符？我该怎么做？

Answer 1

编辑：编辑说我应该回答问题前，请仔细阅读问题;） 要检查的对象是否是无你必须使用Is repsective IsNot关键词：

If this_day Is Nothing Then 

所属：

If this_day IsNot Nothing Then 

---

融为一体原来的答复配对不属于任何对象：

超载平等运营商在你的工作日类：

Public Shared Operator =(x As WorkDay, y As WorkDay) 
     'Code to determine whetther x equals y 
End Operator 

要知道，你还必须重载不等于操作：

Public Shared Operator <>(x As WorkDay, y As WorkDay) 
     'Code to determine whetther x not equals y 
End Operator 

---

对马格努斯的评论：

Public Overrides Function Equals(obj As Object) As Boolean 
    Dim o As WorkDay = TryCast(obj, WorkDay) 
    If o IsNot Nothing Then 
     'check whether o equals Me 
    Else 
     Return False 
    End If 
End Function 

Public Overrides Function GetHashCode() As Integer 
    'return a feasible hashcode of a member of Me e.g. 
    Return Me.StartTime.GetHashCode() XOR Me.EndTime.GetHashCode() 
End Function