list 中的Stream 累加操作

ublic class Test {

    public static void main(String[] args) {
        double sum = 860.10 + 1808.09;
        double sum1 = 1808.09 + 860.10;
        // output is  2668.19
        System.out.println(sum);
        // output is  2668.19
        System.out.println(sum1);
        List<Double> lst = new ArrayList<Double>();
        lst.add(860.10);
        lst.add(1808.09);
        Double res = lst.stream().mapToDouble(d -> d).sum();
        // output is  2668.1900000000005
        System.out.println(res);
        lst.clear();
        // adding in reverse order
        lst.add(1808.09);
        lst.add(860.10);
        res = lst.stream().mapToDouble(d -> d).sum();
        // output is  2668.19
        System.out.println(res);
    }
}