从Excel文件C＃读取列

Question

I have method, which gets the cells from an excel File. The problem is that 'if (usedrange.Cells[1, j] != null)' gives an NullReference Exception. I used that Code at Work on Visual Studio, but now at home its not working. Can someone tell me why?

   public List<string> GetBrandListFromExcel(string path, int sheet)
    {
        var i = 1;
        var j = 1;

        List<string> zelle = new List<string>(); ;
        if (File.Exists(path))
        {
            Workbook wb = excel.Workbooks.Open(path);
            Worksheet ws = (Worksheet)wb.Worksheets[1];
            Range usedrange = ws.UsedRange;

            for (j = 1; j <= 2250; j++)
            {
                if (usedrange.Cells[1, j] != null)
                {
                    var cell = usedrange.Cells[j, 1] as Range;
                    if (cell.Value2 != null)
                    {
                        zelle.Add((string)cell.Text);
                    }
                }
                else
                    continue;
            }
            wb.Close();
        }
        return brands;
    }

Answer 1

From the code, I could see that the usedRange is created from different Worksheet object ( ws1 ) instead of correct one ( ws ). It might be the reason. Change it as below and check.

Worksheet ws = (Worksheet)wb.Worksheets[1];
Range usedrange = ws.UsedRange;