java分日期求和问题

想实现分日期累加求和并添加到excel中， 可是传到excel中的数据把每一天的数据都打出来了。帮忙看一下问题出在哪了？

    double sum = 0;
    double a = 0;
    String cellValue = "";
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd");
    Date date = inputRow.getCell(
            Integer.parseInt(source.getProperty("日期列")) - 1)
            .getDateCellValue();
    cellValue = formatter.format(date);
    ArrayList<String> date1 = new ArrayList<String>();
    ArrayList<Double> value1 = new ArrayList<Double>();
    ArrayList<String> date2 = new ArrayList<String>();
    ArrayList<Double> value2 = new ArrayList<Double>();
    value1.add(inputRow.getCell(
            Integer.parseInt(source.getProperty("求和列")) - 1)
            .getNumericCellValue());
    date1.add(cellValue);
    for (int c = 0; c < date1.size(); c++) {
        try {
            if (date1.get(c).equals(date1.get(c + 1))) {
                a = value1.get(c);
                sum = a + sum;
            } else {
                a = value1.get(c);
                sum = a + sum;
                date2.add(date1.get(c));
                value2.add(sum);
                sum = 0.0;
            }
        } catch (Exception e) {
            a = value1.get(c);
            sum = a + sum;
            date2.add(date1.get(c));
            value2.add(sum);
        }
    }
    for (int k = 0; k < date2.size(); k++) {
        outputRow.createCell(14).setCellValue(value2.get(k));
        outputRow.createCell(3).setCellValue(date2.get(k));
        outputRow.createCell(4).setCellValue(date2.get(k));
    }
}

主函数里的方法，调用的processSum求和方法

for (i = o; i < lastnum; i++) {
                XSSFRow readrow = readsheet.getRow(i);// 获取输入行
                Process p = new ProcessRow();
                if (p.panduan2(readrow)) {
                    XSSFSheet sheet = sc.getSheetAt(0);
                    XSSFRow outputrow = sheet.createRow(j++);
                    p.processSum(readrow, outputrow);
                }
            }