reduce 使用说明

image.png

代码

public static void main(String[] args) {

        List<Stu> list = Lists.newArrayList(new Stu(1, 100L),
                new Stu(2, 200L),
                new Stu(null, 300L));

        /**
         * 注意这里的空指针异常
         */
        Optional<Stu> o = list.stream()
                .filter(e -> e != null && e.age != null)
                .reduce((x, y) -> x.age > y.age ? x : y);

        System.out.println(o.get());

    }

    @Data
    @AllArgsConstructor
    public static class Stu {
        private Integer age;
        private Long money;
    }

结果

TestTest.Stu(age=3, money=300)