使用java8的stream对数组进行求和
1.对BigDecimal类型的值求和
List<Map<String,Object>> list = new ArrayList<>(); Map<String,Object> stu1 = new HashMap<String, Object>(); stu1.put("name", "卫庄"); stu1.put("score", new BigDecimal(80)); list.add(stu1); Map<String,Object> stu2 = new HashMap<String, Object>(); stu2.put("name", "盖聂"); stu2.put("score", new BigDecimal(90)); list.add(stu2); Map<String,Object> stu3 = new HashMap<String, Object>(); 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<Map<String,Object>> list = new ArrayList<>(); Map<String,Object> stu1 = new HashMap<String, Object>(); stu1.put("name", "卫庄"); stu1.put("score", 80.0); list.add(stu1); Map<String,Object> stu2 = new HashMap<String, Object>(); stu2.put("name", "盖聂"); stu2.put("score", 90.0); list.add(stu2); Map<String,Object> stu3 = new HashMap<String, Object>(); 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); //结果:三人总分:230