null使ったら負け福岡版
- 26. Map<?, List<?>>
● 追加
– Map#computeIfAbsent
● 削除
– Map#computeIfPresent
modifiedTuples.computeIfPresent(mt.oldtuple.rid,
(rid, list) -> {
list.remove(mt);
return list.isEmpty() ? null : list;
});
modifiedTuples.computeIfAbsent(mt.oldtuple.rid,
rid -> new LinkedList()).push(mt);
- 33. Pairとzip
http://d.hatena.ne.jp/nowokay/20140321#1395371615
public static void main(String[] args) {
List<String> prefs = Arrays.asList("ほっかいどう", "ちば",
"とうきょう", "しが", "やまぐち",
"さが", "みやざき");
StreamUtils.zip(
IntStream.iterate(1, SUCC).boxed(),
prefs.stream().filter(s -> s.length() <= 2))
.forEach(p -> System.out.printf(
"%d:%s%n", p.left, p.right));
}