Cast Exception Issue. Please help

Question

Hello all,
I have a piece of code that is giving me runtime class cast exception error.
The error occurs whenever code trys to cast the tableData into Strin.
Any insight into why this error occurs I would I appreciate the information:
for (int i=0; i<rowCount; i++)
List tableData = this.tableModel.getRow(i);
System.out.println("we are here 5.1");
row = sheet1.createRow((short)(i+1));
System.out.println("we are here 5.2");
for (int j=0; j<tableData.size(); j++)
String columnData = (String)tableData.get(j);
row.createCell((short)j).setCellValue((String)tableData.get(j));
currentCell++;
frame.current.setValue(currentCell);
}

Answer 1

The scope of the code is taking results of table data(from database) which could be string, number or other data types and converting it into string which in turn gets written to excel spreadsheet cell.
I'm really taking shortcut in that I dont try and figure out the datatype from database value first then try to cast it into appropriate value. Taking the easy way out so to speak...
BTW, I'm relatively new to Java. Still a lot of OJT.