Rxjava2 how to have flatMap emitting items in called order?

Question

Imagining there is Observable A emitting

a1, a2, a3, a4...

A.flatMap(a -> f(a)) will emit items in unpredictable order, for example:

fa3, fa1, fa2, fa4...

How could I get results in order like below?

fa1, fa2, fa3, fa4...

ConcatMap can return the result I want, but it processes streams in sequential order, which is not effective in time consuming. I need something like concatMap with parallel processing ability. Any solution? Thanks.

@zella thks definitely what i'm looking for. Could you post it as an answer? — Hoang Nguyen Huu, Jul 25 '19 at 03:56

score 1 · Accepted Answer · answered Jul 25 '19 at 10:58

1

You can use concatMapEager, which buffers emission and produce items sequentially.

answered Jul 25 '19 at 10:58

zella

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Rxjava2 how to have flatMap emitting items in called order?

1 Answers1