從函數的ParameterizedThreadStart中分配布爾值

Question

我有一個使用ParameterizedThreadStart爲布爾數據類型分配值的問題，它在返回時總是顯示False。

這裏是我的代碼：

'smth 
Frm_ChkHash.Show() 
Frm_ChkHash.BringToFront() 

Dim BoolH As Boolean 
Dim thdC = New Thread(New ParameterizedThreadStart(Function() BoolH = Frm_ChkHash.MatchHash(Keyl))) 
thdC.Start() 
'smth (Wait the thread until exit) 
Debug.WriteLine("It is " & BoolH) 
'smth 

的Debug.WriteLine("It is " & BoolH)顯示False在BoolH

試圖使它可爲空（Dim BoolH? As Boolean），它顯示了BoolH

不信邪，這裏是我的Frm_ChkHash.MatchHash功能代碼：

Public Function MatchHash(ByVal Keyl As String) As Boolean 

    Dim nameApp As String = dicLbl.Item(Keyl) 
    Debug.WriteLine("Hey! I am checking " & nameApp) 

    Thread.Sleep(1500) 
    InitHsh() 
    Thread.Sleep(2000) 

    Dim GetHash As String = KHash.GenerateHash(pathFile, HashCheck.HashType.SHA1) 
    'The KHash.GenerateHash returns a String. 
    Thread.Sleep(1500) 

    'Find the Actual Hash in the Dictionary through the key. 
    Dim ActualHash As String = dicHsh.Item(Keyl) 
    Debug.WriteLine("The actual hash is: " & ActualHash) 

    Dim StrCmp_Hash As Boolean = StringComparer.OrdinalIgnoreCase.Equals(ActualHash, GetHash) 
    Debug.WriteLine("The hash is " & CStr(StrCmp_Hash)) 

    If StrCmp_Hash = True Then 

     Debug.WriteLine("The hash is correct!") 
     Debug.WriteLine("It is cool: " & dicHsh.Item(Keyl)) 
     Debug.WriteLine("And I get : " & GetHash) 

     Thread.Sleep(1500) 
     Hide() 

     Return True 

    Else 

     Debug.WriteLine("I get" & GetHash & "But it is" & dicHsh.Item(Keyl)) 

     Thread.Sleep(1500) 
     Hide() 
     Return False 

    End If 

    Hide() 

End Function 

我的輸出窗口顯示是這樣的：

 
Hey! I am checking ThisApp  <--- This comes from MatchHash function 
The actual hash is: E2133C93F55C7DF4EA44DC0F5455F4A2EE637E8B 
The hash is True 
The hash is correct! 
It is cool: E2133C93F55C7DF4EA44DC0F5455F4A2EE637E8B 
And I get : E2133C93F55C7DF4EA44DC0F5455F4A2EE637E8B 
The thread 0x8cc has exited with code 0 (0x0). <--- IDK where this line comes form 

It is  <--- The function had returned. (After `thdC.start()`) 

任何幫助表示讚賞。

Answer 1

問題是你的delegetate是你的委託中的'='操作符充當比較操作符而不是賦值操作符。

它在做什麼，這是：

Function() 
    return BoolH = Frm_ChkHash.MatchHash(Keyl) 
End If 

這就是爲什麼BoolH爲空，如果你讓它空。

如果要將BoolH賦值，請使用'Sub（）'而不是Function()，或者讓您的委託使用多行語句。

Dim thdC = New Thread(New ParameterizedThreadStart(Sub() BoolH = Frm_ChkHash.MatchHash(Keyl))) 

或：

Dim thdC = New Thread(New ParameterizedThreadStart(Function() 
     BoolH = Frm_ChkHash.MatchHash(Keyl) 
    End Function) 

不是後者現在已經沒有返回值。