vb.net - VB.NET错误-使用结果时，在运行时可能会出现Null引用异常

Question

背景:我编写了将输出所有当前登录的用户Active Directory组名称的代码。我想要通过IdentityReference.Translate的组名(例如:Acomp_user_BIG)，而不是通过IdentityReference.Value返回的当前用户的SID(例如:S-1-5-32-544)。

这是我使用的代码:

Public ReadOnly Property Groups As IdentityReferenceCollection
    Get
         Dim irc As IdentityReferenceCollection
         Dim ir As IdentityReference
         irc = WindowsIdentity.GetCurrent().Groups

         For Each ir In irc
              Dim account As IdentityReference = ir.Translate(GetType(NTAccount))
              Debug.WriteLine(account.Value)
         Next

    End Get
End Property

不幸的是，我在“End Get”上遇到了错误:

   Warning  1   Property 'Groups' doesn't return a value on all code paths. 
                A null reference exception could occur at run time when the 
                result is used. 

有任何解决此错误的建议吗？

Answer 1

Public ReadOnly Property Groups As IdentityReferenceCollection
    Get
         Dim irc As IdentityReferenceCollection
         Dim ir As IdentityReference
         irc = WindowsIdentity.GetCurrent().Groups

         For Each ir In irc
              Dim account As IdentityReference = ir.Translate(GetType(NTAccount))
              Debug.WriteLine(account.Value)
         Next

         **return irc**
    End Get
End Property

但是，通过查看代码可以修改irc，因此您应该创建一个新的IdentityReferenceCollection(假设它具有.add()方法)，然后执行.add(account)
并返回您的新收藏