Vb.net 警告变量'；csCryptoStream'；在指定值之前使用。运行时可能会导致空引用异常

我是VB.Net的新手。我正试图调试我的项目，但我得到一个警告：变量“csCryptoStream”在赋值之前就已经被使用了。运行时可能会导致空引用异常

我怎样才能修好它

Private Sub EncryptOrDecryptFile(strInputFile As String, strOutputFile As String, bytKey As Byte(), bytIV As Byte(), Direction As crypt.CryptoAction)
    ' The following expression was wrapped in a checked-statement
    Try
        Me.fsInput = New FileStream(strInputFile, FileMode.Open, FileAccess.Read)
        Me.fsOutput = New FileStream(strOutputFile, FileMode.OpenOrCreate, FileAccess.Write)
        Me.fsOutput.SetLength(0L)
        Dim bytBuffer As Byte() = New Byte(4096) {}
        Dim lngBytesProcessed As Long = 0L
        Dim lngFileLength As Long = Me.fsInput.Length
        Dim cspRijndael As RijndaelManaged = New RijndaelManaged()
        Me.pbStatus.Value = 0
        Me.pbStatus.Maximum = 100
        Dim csCryptoStream As CryptoStream
        Select Case Direction
            Case crypt.CryptoAction.ActionEncrypt
                csCryptoStream = New CryptoStream(Me.fsOutput, cspRijndael.CreateEncryptor(bytKey, bytIV), CryptoStreamMode.Write)
            Case crypt.CryptoAction.ActionDecrypt
                csCryptoStream = New CryptoStream(Me.fsOutput, cspRijndael.CreateDecryptor(bytKey, bytIV), CryptoStreamMode.Write)
        End Select
        While lngBytesProcessed < lngFileLength
            Dim intBytesInCurrentBlock As Integer = Me.fsInput.Read(bytBuffer, 0, 4096)

Warning --->     csCryptoStream.Write(bytBuffer, 0, intBytesInCurrentBlock)
            ' The following expression was wrapped in a unchecked-expression
            lngBytesProcessed += CLng(intBytesInCurrentBlock)
            ' The following expression was wrapped in a unchecked-expression
            Me.pbStatus.Value = CInt(Math.Round(CDec(lngBytesProcessed) / CDec(lngFileLength) * 100.0))
        End While

Private Sub-encryptorsecryptfile（strInputFile作为字符串，strOutputFile作为字符串，bytKey作为Byte（），bytIV作为Byte（），Direction作为crypt.cryptoction）
'以下表达式被包装在checked语句中
尝试
Me.fsInput=newfilestream（strInputFile，FileMode.Open，FileAccess.Read）
Me.fsOutput=新文件流（strOutputFile、FileMode.OpenOrCreate、FileAccess.Write）
Me.fsOutput.SetLength（0L）
Dim bytBuffer As Byte（）=新字节（4096）{}
当长度=0L时，处理的字节数变小
Dim lngFileLength As Long=Me.fsInput.Length
Dim cspRijndael As RijndaelManaged=New RijndaelManaged（）
Me.pbStatus.Value=0
Me.pbStatus.max=100
Dim csCryptoStream作为加密流
选择案例方向
Case crypt.CryptoAction.ActionEncrypt
csCryptoStream=新加密流（Me.fsOutput，cspRijndael.CreateEncryptor（bytKey，bytIV），CryptoStreamMode.Write）
Case crypt.CryptoAction.ActionDecrypt
csCryptoStream=新加密流（Me.fsOutput，cspRijndael.CreateDecryptor（bytKey，bytIV），CryptoStreamMode.Write）
结束选择
而LngBytes进程小于lngFileLength
Dim INTBYTESINRENTBLOCK作为整数=Me.fsInput.Read（bytBuffer，0，4096）
警告--->csCryptoStream.Write（bytBuffer，0，intBytesInCurrentBlock）
'以下表达式被包装在未选中的表达式中
lngBytesProcessed+=CLng（intBytesInCurrentBlock）
'以下表达式被包装在未选中的表达式中
Me.pbStatus.Value=CInt（数学四舍五入（CDec（LNGBytes处理）/CDec（lngFileLength）*100.0））
结束时

声明

加密流

，如下所示：

 Dim csCryptoStream As CryptoStream = Nothing

在

Case/Select中添加“
Case-Else
”子句

在使用此变量之前，请检查

If Not IsNothing(csCryptoStream)
  '    ....
End If

---

在使用它之前为它赋值可能是首先尝试的显而易见的事情…我在尝试调试时遇到了其他错误：Microsoft.VisualBasic.ApplicationServices.NoStartupFormException类型的未处理异常在Microsoft.VisualBasic中发生。dll@MuhammadFathan如果您在该行中遇到错误，请尝试将其声明为“新建”i、 e.Dim CcryptoStream作为新的加密流