Java Stream API cheat sheet

Stream super convenient. Stream Justice, and Stream forget soon. So I made a cheat sheet. Thank you for your consideration.

Process everything (List)

Arrays.asList("honto", "world", "tough").stream().forEach(s -> System.out.println(s));
Arrays.asList("Seriously", "really", "tough").stream().forEach(System.out::println);

Process everything (Map)

  .forEach(e -> System.out.println(e.getKey() + ":" + e.getValue()));

Process only specific items.

Arrays.asList("love", "Love", "Money", "dream").stream()
  .filter(s -> s.equals("Love")).forEach(System.out::println);

Type conversion.

Arrays.asList("1", "2", "3", "5").stream()
  .map(s -> Integer.valueOf(s)).forEach(System.out::println);

Process for a specific range of numbers.

IntStream.range(0, 10).map(i -> i*2).toArray();

Change from List to Map.

  .map(s -> s.split(" ",2)).filter(a -> 2 == a.length)
  .collect(Collectors.toMap(a->a[0], a->a[1]));

Process at high speed with multiple threads.

Arrays.asList("love", "Love", "Money", "dream").parallelStream()
  .findFirst(s -> s.equals("Love"));

List join

Arrays.asList("Love,that is,Sweet","Love,that is,strongly","Love,that is,Noble").stream()
  .map(s -> s.split(",")).flatMap(a -> Arrays.asList(a).stream())

Variable when it gets longer.

Function<String, String> toHakata = s -> {
    return s + "Toyo.";
Arrays.asList("Sogyan Kotsunaka").stream().map(toHakata);

If there are others

Please comment and pull request.

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