VerifyError

[Richard Warburton]

> It's a compiler issue,
> in the following expression, the lambda used as parameter of flatMap
> is not able to create CoBuy::new correctly
>
> // product id -> product id -> frequency purchased together
>          Map<Integer, Map<Integer, Long>> productSimilarity =
>                  buysByUser.values()
>                            .stream()
>                            .flatMap(buys -> zip(buys.stream(),
> buys.stream(), CoBuy::new))
>                            .collect(groupingBy(coBuy -> coBuy.x,
>                                     groupingBy(coBuy -> coBuy.y,
> TreeMap::new, counting())));
>
> so the bug is here:
>          buys -> zip(buys.stream(), buys.stream(), CoBuy::new)
>
> CoBuy is declared as a non static inner class
> (BTW, Richard, I think you forget to declare it static)
> so it capture 'this' which is an instance of Java8Recommender.
>

Makes perfect sense, and making CoBuy static fixes the problem.

regards,

  Richard Warburton

  http://insightfullogic.com
  @RichardWarburto <http://twitter.com/richardwarburto>