JAVA8对象属性的计算

 Men men = new Men();
        men.setName("UU");
        men.setAge("56");
        Men men1 = new Men();
        men1.setName("KK");
        men1.setAge("23");
        Men men2 = new Men();
        men2.setName("KK");
        men2.setAge("");

        List<Men> list = new ArrayList<>();
        list.add(men);
        list.add(men1);
        list.add(men2);

        //一般写法
        int sum =0;
        for (Men men3 : list) {
            if (men3.getName().equals("KK")) {
                sum = sum + Integer.parseInt(men3.getAge().isEmpty()?"0":men3.getAge());
            }
        }

        //JAVA8新特性
        int kk = list
                .stream()
                .filter(t -> t.getName().equals("KK"))
                .mapToInt(t -> Integer.parseInt(t.getAge().isEmpty()?"0":t.getAge()))
                .sum();

        System.out.println(kk);

Map

Map<String, Object> map = new HashMap<>();
        map.put("KK", "123");

        String text = Optional.ofNullable(map.get("KK"))
                .map(value -> value.toString().trim())
                .orElse("");
        System.out.println(text);