Java 16: Stream.mapMulti for one-to-many mapping

mapMulti pushes zero-or-more results per element without creating intermediate streams.

Code

List<Integer> nums = List.of(1, 2, 3);
List<Integer> withDoubles = nums.stream()
        .<Integer>mapMulti((n, consumer) -> {
            consumer.accept(n);
            consumer.accept(n * 10);
        })
        .toList();
System.out.println(withDoubles);

Output

[1, 10, 2, 20, 3, 30]

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Published 2026-07-26