Multi provides the ability to:
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only forward items from the beginning of the observed multi,
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only forward the last items (and discard all the other ones),
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skip items from the beginning of the multi,
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skip the last items.
Taking items
The multi.transform().byTakingFirstItems method forwards on the n first items from the multi.
It forwards that amount of items and then sends the completion signal.
It also cancels the upstream subscription.
Multi<Integer> firstThreeItems = multi.transform().byTakingFirstItems(3);If the observed multi emits fewer items, it sends the completion event when the upstream completes.
Similarly, The multi.transform().byTakingLastItems operator forwards on the n last items from the multi.
It discards all the items emitted beforehand.
Multi<Integer> lastThreeItems = multi.transform().byTakingLastItems(3);The multi.transform().byTakingItemsWhile operator forwards the items while the passed predicate returns true:
Multi<Integer> takeWhile = multi.transform().byTakingItemsWhile(i -> i < 4);It calls the predicates for each item.
Once the predicate returns false, it stops forwarding the items downstream.
It also sends the completion event and cancels the upstream subscription.
Finally, multi.transform().byTakingItemsFor operator picks the first items for a given period.
Once the passed duration expires, it sends the completion event and cancels the upstream subscription.
If the observes multi completes before the passed duration, it sends the completion event.
Multi<Integer> takeForDuration = multi.transform().byTakingItemsFor(Duration.ofSeconds(1));Skipping items
You can also skip items.
The multi.transform().bySkippingFirstItems method skips the n first items from the multi.
It forwards all the remaining items and sends the completion event when the upstream multi completes.
Multi<Integer> skipThreeItems = multi.transform().bySkippingFirstItems(3);If the observed multi emits fewer items, it sends the completion event without emitting any items.
Similarly, The multi.transform().bySkippingLastItems operator skips on the n last items from the multi:
Multi<Integer> skipLastThreeItems = multi.transform().bySkippingLastItems(3);The multi.transform().bySkippingItemsWhile operator skips the items while the passed predicate returns true:
Multi<Integer> skipWhile = multi.transform().bySkippingItemsWhile(i -> i < 4);It calls the predicates for each item.
Once the predicate returns false, it stops discarding the items and starts forwarding downstream.
Finally, multi.transform().bySkippingItemsFor operator skips the first items for a given period.
Once the passed duration expires, it sends the items emitted after the deadline downstream.
If the observes multi completes before the passed duration, it sends the completion event.
Multi<Integer> skipForDuration = multi.transform().bySkippingItemsFor(Duration.ofSeconds(1));