Perform multiple unrelated operations on elements of a single stream in Java

Question

How can I perform multiple unrelated operations on elements of a single stream?

Say I have a List composed from a text. Each string in the

Answer 1

You could use a custom collector for that and iterate only once:

 private static  Collector, List>> multiple() {

    class Acc {

        List strings = new ArrayList<>();

        List longs = new ArrayList<>();

        void add(String elem) {
            if (elem.contains("of")) {
                long howMany = Arrays.stream(elem.split(" ")).count();
                longs.add(howMany);
            }
            if (elem.contains("for")) {
                String result = elem.substring(elem.indexOf("for"));
                strings.add(result);
            }

        }

        Acc merge(Acc right) {
            longs.addAll(right.longs);
            strings.addAll(right.strings);
            return this;
        }

        public Pair, List> finisher() {
            return Pair.of(strings, longs);
        }

    }
    return Collector.of(Acc::new, Acc::add, Acc::merge, Acc::finisher);
}

Usage would be:

Pair, List> pair = Stream.of("t of r m", "t of r m", "nice for nice nice again")
            .collect(multiple());