IntStream.sum (original) (raw)

Remi Forax forax at univ-mlv.fr
Wed Jan 16 03:58:02 PST 2013

IntStream.sum have just been changed to return a long instead of an int and I don't think it's a good idea.

There is 3 ways to deal with overflows:

  1. do nothing, the Java default semantics
  2. throw an exception if overflown (using Integer.addExact by example)
  3. use BigInteger all other ways are just half baked solution.

This one is very bad because usually users will use it that way, int sum = (int)intStream.sum(); so it doesn't solve anything, just make the semantics awkward.

sum() is just a shortcut for a reduce, so it should stick with the default Java semantics, if users want longs, they can use reduce with Long::add or Long::addExact.

Rémi

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