编译器警告:null引用异常

我在Visual Studio 2005中有以下代码.

    Dim OutFile As System.IO.StreamWriter
    Try
        OutFile = New System.IO.StreamWriter(Filename)
       // Do stuff with OutFile
    Catch Ex As Exception
       // Handle Exception
    Finally
       If OutFile IsNot Nothing Then OutFile.Close()
    End Try

但VS2005提出警告"If OutFile IsNot .."这一行

变量'OutFile'在被赋值之前使用.在运行时可能会导致空引用异常.

有没有办法通过巧妙地改变代码来消除这个警告,或者只是有更好的方法来做我正在尝试做的事情？

谢谢

抢

Dim OutFile As System.IO.StreamWriter
OutFile = Nothing
Try
    OutFile = New System.IO.StreamWriter(Filename)
   // Do stuff with OutFile
Catch Ex As Exception
   // Handle Exception
Finally
   If OutFile IsNot Nothing Then OutFile.Close()
End Try

与C#错误类似:使用未分配的局部变量