{"id":91202,"date":"2024-03-21T13:33:32","date_gmt":"2024-03-21T04:33:32","guid":{"rendered":"https:\/\/www.silicloud.com\/ja\/blog\/java-%e3%82%b9%e3%83%88%e3%83%aa%e3%83%bc%e3%83%a0%e3%81%a7-nullpointerexception-%e3%82%92%e5%9b%9e%e9%81%bf%e3%81%99%e3%82%8b%e6%96%b9%e6%b3%95\/"},"modified":"2024-03-27T19:19:15","modified_gmt":"2024-03-27T10:19:15","slug":"java-%e3%82%b9%e3%83%88%e3%83%aa%e3%83%bc%e3%83%a0%e3%81%a7-nullpointerexception-%e3%82%92%e5%9b%9e%e9%81%bf%e3%81%99%e3%82%8b%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/ja\/blog\/java-%e3%82%b9%e3%83%88%e3%83%aa%e3%83%bc%e3%83%a0%e3%81%a7-nullpointerexception-%e3%82%92%e5%9b%9e%e9%81%bf%e3%81%99%e3%82%8b%e6%96%b9%e6%b3%95\/","title":{"rendered":"Java \u30b9\u30c8\u30ea\u30fc\u30e0\u3067 NullPointerException \u3092\u56de\u907f\u3059\u308b\u65b9\u6cd5"},"content":{"rendered":"

Java 8 \u306e Stream \u3092\u4f7f\u7528\u3057\u3066\u3044\u3066 NullPointerException \u3092\u907f\u3051\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n

    \n
  1. Optional \u30af\u30e9\u30b9\u306e\u5229\u7528\uff1aOptional \u30af\u30e9\u30b9\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u3067\u3001null \u306b\u306a\u308a\u5f97\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30e9\u30c3\u30d7\u3057\u3001Optional \u30af\u30e9\u30b9\u306e\u30e1\u30bd\u30c3\u30c9\u306b\u3088\u3063\u3066\u64cd\u4f5c\u3059\u308b\u3053\u3068\u3067 NullPointerException \u3092\u56de\u907f\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/ol>\n
    Optional<String> optional = Optional.ofNullable(str);\r\noptional.ifPresent(s -> System.out.println(s));\r\n<\/code><\/pre>\n
      \n
    1. \u7a7a\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092filter\u30e1\u30bd\u30c3\u30c9\u3067\u53d6\u308a\u9664\u304f\uff1a\u7a7a\u3067\u306a\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3060\u3051\u51e6\u7406\u3059\u308b\u305f\u3081\u3001filter\u30e1\u30bd\u30c3\u30c9\u3067\u7a7a\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u9664\u304d\u3001\u51e6\u7406\u5bfe\u8c61\u304b\u3089\u53d6\u308a\u9664\u304f\u3002<\/li>\n<\/ol>\n
      List<String> list = Arrays.asList(\"apple\"<\/span>, null<\/span>, \"orange\"<\/span>, null<\/span>, \"banana\"<\/span>);\r\nlist.stream()\r\n    .filter(s -> s != null<\/span>)\r\n    .forEach(System.out::println);\r\n<\/code><\/pre>\n
        \n
      1. \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u5909\u63db\u3059\u308b\u3068\u304d\u306fmap\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u7a7a\u306e\u5834\u5408\u306f\u3001Optional \u30af\u30e9\u30b9\u3092\u4f7f\u7528\u3057\u3066\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30e9\u30c3\u30d7\u3057\u3001\u30cc\u30eb\u30dd\u30a4\u30f3\u30bf\u4f8b\u5916\u3092\u56de\u907f\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/ol>\n
        List<String> list = Arrays.asList(\"apple\"<\/span>, null<\/span>, \"orange\"<\/span>, null<\/span>, \"banana\"<\/span>);\r\nlist.stream()\r\n    .map(Optional::ofNullable)\r\n    .forEach(optional -> optional.ifPresent(System.out::println));\r\n<\/code><\/pre>\n
          \n
        1. flatMap\u3001filter\u30e1\u30bd\u30c3\u30c9\u4f7f\u7528\uff1aflatMap\u30e1\u30bd\u30c3\u30c9\u3067\u30b9\u30c8\u30ea\u30fc\u30e0\u5185\u306e\u5404\u8981\u7d20\u3092\u30b9\u30c8\u30ea\u30fc\u30e0\u306b\u5909\u63db\u3057\u3001filter\u30e1\u30bd\u30c3\u30c9\u3067\u7a7a\u30b9\u30c8\u30ea\u30fc\u30e0\u3092\u9664\u5916\u3059\u308b\u3053\u3068\u3067NullPointerException\u3092\u9632\u3050\u3002<\/li>\n<\/ol>\n
          List<List<String>> list = Arrays.asList(\r\n    Arrays.asList(\"apple\"<\/span>, \"orange\"<\/span>),\r\n    null<\/span>,\r\n    Arrays.asList(\"banana\"<\/span>, \"grape\"<\/span>),\r\n    null<\/span>\r\n);\r\nlist.stream()\r\n    .flatMap(Collection::stream)\r\n    .filter(s -> s != null<\/span>)\r\n    .forEach(System.out::println);\r\n<\/code><\/pre>\n
          \u7a7a\u30dd\u30a4\u30f3\u30bf\u4f8b\u5916\u3092 Java \u30b9\u30c8\u30ea\u30fc\u30e0\u3067\u56de\u907f\u3059\u308b\u65b9\u6cd5\u306f\u524d\u8ff0\u306e\u3068\u304a\u308a\u3067\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
          Java 8 \u306e Stream \u3092\u4f7f\u7528\u3057\u3066\u3044\u3066 NullPointerException \u3092\u907f\u3051\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002 Optional \u30af\u30e9\u30b9\u306e\u5229\u7528\uff1aOptional \u30af\u30e9\u30b9\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u3067\u3001null \u306b\u306a\u308a\u5f97 […]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-91202","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\nJava \u30b9\u30c8\u30ea\u30fc\u30e0\u3067 NullPointerException \u3092\u56de\u907f\u3059\u308b\u65b9\u6cd5 - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/ja\/blog\/java-\u30b9\u30c8\u30ea\u30fc\u30e0\u3067-nullpointerexception-\u3092\u56de\u907f\u3059\u308b\u65b9\u6cd5\/\" \/>\n<meta property=\"og:locale\" content=\"ja_JP\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Java \u30b9\u30c8\u30ea\u30fc\u30e0\u3067 NullPointerException \u3092\u56de\u907f\u3059\u308b\u65b9\u6cd5\" \/>\n<meta property=\"og:description\" content=\"Java 8 \u306e Stream \u3092\u4f7f\u7528\u3057\u3066\u3044\u3066 NullPointerException \u3092\u907f\u3051\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002 Optional \u30af\u30e9\u30b9\u306e\u5229\u7528\uff1aOptional \u30af\u30e9\u30b9\u3092\u5229\u7528\u3059\u308b\u3053\u3068\u3067\u3001null \u306b\u306a\u308a\u5f97 […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/ja\/blog\/java-\u30b9\u30c8\u30ea\u30fc\u30e0\u3067-nullpointerexception-\u3092\u56de\u907f\u3059\u308b\u65b9\u6cd5\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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