问对ArrayList<Integer>中的所有条目求和

EN

    for (Kids ki : GroupOfKids) {

        try {
            DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
            Date date = new Date();
            String currentDate= dateFormat.format(date);
            Date datum;
            datum = dateFormat.parse(currentDate);


            Date bornDate;
            bornDate= ki.getbornDate();

            int days = daysBetween(bornDate, datum);               
            //code above works fine..from here it's getting confusing

            List<Integer> allKids;
            allKids= new ArrayList<>();
            allKids.add(days);

            int total;
        total = allKids.stream().mapToInt(Integer::intValue).sum();
    System.out.print(total);


        } catch (Exception e) {
            e.printStackTrace();
        }

    }