Read and Write excel file with POI library

Here is the simple code for reading and writing excel file with POI library

public void processExcel() throws FileNotFoundException {
        InputStream is = this.getClass().getResourceAsStream("/testpoi/ExcelFile.xls");
        FileInputStream fis = new FileInputStream("D://ExcelFile.xls");
        FileOutputStream fos = null;
        try {
            //HSSFWorkbook workbook = new HSSFWorkbook(is);
            HSSFWorkbook workbook = new HSSFWorkbook(fis);
            HSSFSheet sheet = workbook.getSheetAt(0);
            HSSFCell cell = null;
            int rows = sheet.getLastRowNum();
            //System.out.println("Total rows: " + rows);

            for (int i = 0; i < rows; i++) {
                double total = 0;
                for (int j = 0; j < 3; j++) {
                    cell = sheet.getRow(i + 1).getCell(j);
                    if (cell == null || cell.getCellType() == HSSFCell.CELL_TYPE_BLANK
                            || cell.getCellType() == HSSFCell.CELL_TYPE_ERROR) {
                        continue;
                    }
                    if (cell.getCellType() == HSSFCell.CELL_TYPE_NUMERIC) {
                        double value = cell.getNumericCellValue();
                        //System.out.println("Value: " + value);
                        total += value;
                    }
                }
                vtResult.add(total);
            }
           
            //out result
            for (int h = 0; h < vtResult.size(); h++) {
                cell = sheet.getRow(h + 1).getCell(3);
                cell.setCellValue(vtResult.get(h));
            }

            // write workbook
            fos = new FileOutputStream("e://output.xls");
            workbook.write(fos);
            fos.close();
            workbook = null;
        } catch (IOException ex) {
            Logger.getLogger(ExcelUtil.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                is.close();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }