使用stream把对象中的属性过滤出来后转成list后求和例子

写一个简单的例子 相信聪明如你一看就懂

User user = new User("a",1,"男");
        User user1 = new User("b",3,"女");
        User user2 = new User("c",5,"男");
        List<User> users = new ArrayList<>();
        users.add(user);
        users.add(user1);
        users.add(user2);
        //过滤
        List<Integer> ageList= users.stream().map(i -> i.getAge()).distinct().collect(Collectors.toList());
        //求和[基数从0开始做累加]
        Integer ageSum= collect.stream().reduce(0, Integer::sum);
        System.out.println("reduce1 = "+ reduce1);