How to combine two Fluxes of Pairs sharing a equal element

Question

I want to combine (zip) the following streams:

s1 = [1, A], [2, B], [3, C]

s2 = [1, X], [3, XX]

And get:

result = [1, Pair(A, X)], [2, Pair(B, null)], [3, Pair(C, XX)]

Is there a clean and efficient way to do this?

Thanks in advance for any help.

You need to specify your requirements more clearly. You only show elements that are emitted, but neither how or when they are emitted nor what the relation between those are. — a better oliver

Pedro Alipio Pedro Alipio · Accepted Answer · 2018-05-30T15:12:55

I guess I found the answer in https://blog.jooq.org/2015/08/13/common-sql-clauses-and-their-equivalents-in-java-8-streams. What I wanted was an inner join. Something like this:

s1
  .flatMap(v1 -> s2
                   .filter(v2 -> v1.left().equals(v2.left()))
                   .map(v2 -> Pair.of(v1, Pair.of(v1.right(), v2.right())))

How to combine two Fluxes of Pairs sharing a equal element

1 Answers