1.对BigDecimal类型的值求和
List> list = new ArrayList<>(); Map stu1 = new HashMap(); stu1.put("name", "卫庄"); stu1.put("score", new BigDecimal(80)); list.add(stu1); Map stu2 = new HashMap(); stu2.put("name", "盖聂"); stu2.put("score", new BigDecimal(90)); list.add(stu2); Map stu3 = new HashMap(); stu3.put("name", "天明"); stu3.put("score", new BigDecimal(60)); list.add(stu3); BigDecimal sum = list.stream().map(x -> new BigDecimal(x.get("score").toString())).reduce(BigDecimal.ZERO,BigDecimal::add); System.out.println("三人总分:"+sum);
//结果:三人总分:230
2.对double型的值求和
List> list = new ArrayList<>(); Map stu1 = new HashMap(); stu1.put("name", "卫庄"); stu1.put("score", 80.0); list.add(stu1); Map stu2 = new HashMap(); stu2.put("name", "盖聂"); stu2.put("score", 90.0); list.add(stu2); Map stu3 = new HashMap(); stu3.put("name", "天明"); stu3.put("score", 60.0); list.add(stu3); double sum = list.stream().collect(Collectors.summingDouble(x -> ((Double) x.get("score")))); System.out.println("三人总分:"+sum);
转载于:https://www.cnblogs.com/sikuaiwu/p/11387107.html