Hello!
The following code prints -1 twice, while users would normally expect
something like 9.223372036854776E18:
double avg1 = Stream.of(Long.MAX_VALUE, Long.MAX_VALUE).collect(
Collectors.averagingLong(Long::valueOf));
System.out.println(avg1);
double avg2 = LongStream.of(Long.MAX_VALUE, Long.MAX_VALUE).average()
.getAsDouble();
System.out.println(avg2);
That's because in both cases internally sum is calculated in the long
variable where it may silently overflow. The documentation for both
methods says nothing about such possibility. I guess if it's too late
to fix this behavior, then probably it should be at least properly
documented?
With best regards,
Tagir Valeev.
