reduce补充

System.out.println("求和:" + random.ints().limit(10).boxed().reduce(Integer::sum).orElseThrow(() -> new RuntimeException("求和失败")));
        System.out.println("求和2:" + random.ints().limit(10).boxed().reduce(0, Integer::sum));

System.out.println("求和3:" + random.ints().limit(10).boxed().reduce(0, (i1, i2) -> Integer.sum(i1, i2), (i1, i2) -> null));

System.out.println("求和3:" + random.ints().limit(10).boxed().reduce(0, Integer::sum, Integer::sum));