{"provider_name":"Hatena Blog","image_url":null,"provider_url":"https://hatena.blog","url":"https://mike-neck.hatenadiary.com/entry/2014/10/05/211758","author_url":"https://blog.hatena.ne.jp/mike_neck/","title":"Java8\u306eOptional\u306e\u4f7f\u3044\u65b9\u30e1\u30e2","blog_title":"mike-neck\u306e\u30d6\u30ed\u30b0","categories":["Java"],"html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fmike-neck.hatenadiary.com%2Fentry%2F2014%2F10%2F05%2F211758\" title=\"Java8\u306eOptional\u306e\u4f7f\u3044\u65b9\u30e1\u30e2 - mike-neck\u306e\u30d6\u30ed\u30b0\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","published":"2014-10-05 21:17:58","blog_url":"https://mike-neck.hatenadiary.com/","author_name":"mike_neck","type":"rich","version":"1.0","description":"\u3053\u3093\u306b\u3061\u308f\u3001\u307f\u3051\u3067\u3059\u3002 2014/10/10\u306eScala\u52c9\u5f37\u4f1a\u306b\u5411\u3051\u3066Scala\u3092\u3084\u3063\u3066\u305f\u3089\u3001 Optional<T>\u306e\u81ea\u5206\u3067\u3082\u3044\u3044\u3068\u611f\u3058\u308b\u66f8\u304d\u65b9\u304c\u308f\u304b\u3063\u3066\u304d\u305f\u3064\u3082\u308a\u306a\u306e\u3067\u3001 \u30e1\u30e2\u66f8\u304d\u3057\u3066\u304a\u304d\u307e\u3059\u3002 Optional<T>\u3092\u4f7f\u3046\u3068\u304d\u306e\u81ea\u5206\u7684\u306a\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3002 #isPresent\u306f\u4f7f\u308f\u306a\u3044 \u6975\u529b#map(Function<T, R>)\u3084#filter(Predicate<T>)\u3084#flatMap(Function<T, Optional<R>)\u3092\u7528\u3044\u308b \u6700\u5f8c\u306b#orElse(T)\u3001#orElseGet(Supplier<T>)\u3092\u7528\u3044\u308b #isPresent\u306f\u4f7f\u308f\u306a\u3044 \u3053\u308c\u306f\u4f7f\u308f\u306a\u3044\u3068\u3044\u3046\u3088\u2026","height":"190","width":"100%"}