.Net-将代码段从C#转换为VB.Net时出现的问题

if ((currentItem.Tag as FileSystemKind?) != FileSystemKind.File)
            {
                if (currentFileName == GOBACK)
                    currentPath = currentPath.Substring(0, currentPath.Length - Path.GetFileName(currentPath).Length - 1);
                else
                    currentPath = Path.Combine(currentPath, currentFileName);
                UpdateControls();
            }
            else
            {
                //If it's a file, we should return the selected filename
                fileName = Path.Combine(currentPath, currentFileName);
                EndOk();
            }

if ((currentItem.Tag as FileSystemKind?) != FileSystemKind.File)

第一个:

If (TryCast(currentItem.Tag, FileSystemKind)?) <> FileSystemKind.File Then

第二个:

If TryCast(currentItem.Tag, System.Nullable(Of FileSystemKind)) <> FileSystemKind.File Then

谢谢!