POI Help

Question

Hi,
I know that this isn't the ideal place to ask for help for the Apache POI library, but I don't know where exactly to go for help. Can anyone point me to a source or forum that I can look at?
Here's the long version of the story: I am trying to create a .xls file from a .xlt file. I have two templates, and I wrote sample code that basically creates a HSSFWorkbook from the template (in the form of a FileInputStream) and plugs in the String "TEST" into cell D1. It works fine for one template but not the other; I get a NullPointerException when I try to get the first cell of row D. Oddly, I get past that point occasionally but the opening the output file results in a "Unable to read file" error in Excel. I don't quite know where to start looking for help, so I hope someone can kindly point me in the right direction. Any help or advice with regards to debugging this problem would be greatly appreciated. Thanks in advance!

Answer 1

I made a mistake when I described the results. For some reason, I encountered a NullPointerException when I executed sheets.getRow(3). I inspected the properties of the object and discovered that the rows object (a Treemap) in sheets is of size 751, even though sheets.getFirstRowNum is 0 and sheets.getLastRowNum is 758!
When I changed to sheets.getRow(23), it got past the line but rows.getFirstCellNum resulted in 1, so executing cell.setCellValue("TEST") resulted in a NullPointerException. When I assigned row.getCell((short)0) to the cell object instead of row.getCell((short)1), the method terminated with error, but opening "result.xls" generated a "unable to read file" error.
At first, I suspected that the template was not read in properly, but then I located cell B10 (which says "Symbol" in the template) in my method by setting row to sheets.getRow(9) and setting cell to row.getCell((short)1), and right before cell.setCellValue("TEST"), I printed cell.getStringCellValue, which printed "Symbol". I concluded that the template seems to be read in properly.
Here is the modified code:
public void generateFile() {
FileInputStream f = new FileInputStream("template.xlt");
HSSFWorkbook wb = new HSSFWorkbook(f, true);
HSSFSheet sheet = wb.getSheetAt(0);
System.out.println(sheet.getFirstRowNum()); // returns 0
System.out.println(sheet.getLastRowNum()); // returns 757
HSSFRow row = sheet.getRow(9);
System.out.println(row.getFirstCellNum()); // returns 1
System.out.println(row.getLastCellNum()); // returns 11
HSSFCell cell = row.getCell((short)1);
System.out.println("Before edit: " + cell.getStringCellValue()); //prints "Symbol"
cell.setCellValue("TEST");
System.out.println("After edit: " + cell.getStringCellValue()); //prints "TEST"
FileOutputStream out = new FileOutputStream("result.xls");
wb.write(out);
out.close();
} // generateFile
I guess my question at this point is, why are the container objects not correctly reflecting the objects stored? (i.e. How come the last row of sheets is 757 but the size of its row Treemap is only 751?) And why can't I access the first column of the spreadsheet?