Question

I am trying to compile the following code and i am getting the error:

Cannot create instance of abstract class . Please help

m_objExcel = new Excel.Application();
m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks;
m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt));
m_objSheets = (Excel.Sheets)m_objBook.Worksheets;
m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1));

// Create an array for the headers and add it to cells A1:C1.
object[] objHeaders = {"Order ID", "Amount", "Tax"};
m_objRange = m_objSheet.get_Range("A1", "C1");
m_objRange.Value = objHeaders;
m_objFont = m_objRange.Font;
m_objFont.Bold=true;

// Create an array with 3 columns and 100 rows and add it to
// the worksheet starting at cell A2.
object[,] objData = new Object[100,3];
Random rdm = new Random((int)DateTime.Now.Ticks);
double nOrderAmt, nTax;
for(int r=0;r<100;r++)
{
    objData[r,0] = "ORD" + r.ToString("0000");
    nOrderAmt = rdm.Next(1000);
    objData[r,1] = nOrderAmt.ToString("c");
    nTax = nOrderAmt*0.07;
    objData[r,2] = nTax.ToString("c");
}
m_objRange = m_objSheet.get_Range("A2", m_objOpt);
m_objRange = m_objRange.get_Resize(100,3);
m_objRange.Value = objData;

// Save the Workbook and quit Excel.
m_objBook.SaveAs(m_strSampleFolder + "Book2.xls", m_objOpt, m_objOpt,
    m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange,
    m_objOpt, m_objOpt, m_objOpt, m_objOpt);
m_objBook.Close(false, m_objOpt, m_objOpt);
m_objExcel.Quit();

Answer 1

I would suggest you determine the line where it is breaking…

Abstract classes can not be created directly, instead you need to create an instance via a derived class, that is why you are getting the exception.

If you don’t wrap the code with a try/catch or turn on the “Common Language Runtime Exceptions” (default shortcut is Ctrl+E in VS2008) then you should be able to find the line causing the problem.

I think it might even be your first line, normally you use something like:

new ApplicationClass();