Apache POI setting cells to 0

Question

I'm using Apache POI to generate cells but I'm noticing that it seems to set all my cells to the same value. In this case 0. I don't really see why. When I am about to save my sheet to file I can see that the cells have values, but when looking at the generated file it is empty. Any help would be greatly appreciated.

Here is a screen of the debugging when I can see that some cells have values(such as the "5" in the debug window):

Here is the code I am using to generate the sheet:

@Override
public void generate(TableRepresentation tableRepresentation) {
    int rows = tableRepresentation.getRows();
    int columns = tableRepresentation.getColumns();
    final HSSFWorkbook workbook = new HSSFWorkbook();
    final HSSFSheet sheet = workbook.createSheet();
    for (int i = 0; i < rows; i++) {

        final HSSFRow row = sheet.createRow(i);
        for (int j = 0; j < columns; j++) {
            row.createCell(j).setCellValue(tableRepresentation.get(i, j));
        }

    }

    try {
        final FileOutputStream fos = new FileOutputStream("tjockis.xls");

        workbook.write(fos);
        fos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    System.out.println("tjockis.xls" + " written successfully");

}

public interface TableRepresentation {
    int getRows();

    int getColumns();

    String get(int i, int j);
}

EDIT:

Here is how the exported sheet looks:

Answer 1

If you make any variable as final , you cannot change the value of final variable(It will be constant).

A final variable may only be assigned to once and its value will not change and can help avoid programming errors.

Once a final variable has been assigned, it always contains the same value. If a final variable holds a reference to an object, then the state of the object may be changed by operations on the object, but the variable will always refer to the same object.