{"id":31090,"date":"2023-10-25T20:52:49","date_gmt":"2023-08-23T01:12:46","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/java%e7%9a%84stream-api%e5%92%8coptional\/"},"modified":"2025-08-12T22:16:33","modified_gmt":"2025-08-12T14:16:33","slug":"java%e7%9a%84stream-api%e5%92%8coptional","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/java%e7%9a%84stream-api%e5%92%8coptional\/","title":{"rendered":"Java\u7684Stream API\u548cOptional"},"content":{"rendered":"

\u56e0\u4e3a\u5728\u516c\u53f8\u4e3e\u529e\u4e86\u4e13\u4e3aJava\u521d\u5b66\u8005\u51c6\u5907\u7684\u5b66\u4e60\u4f1a\uff0c\u5e76\u5b66\u4e60\u4e86StreamAPI\u548cOptional\uff0c\u6240\u4ee5\u6211\u5199\u4e86\u4e00\u7bc7\u6587\u7ae0\u3002<\/p>\n

\u6d41 API<\/h3>\n

Stream API\u662f\u7528\u4e8e\u5728\u96c6\u5408\u7684\u5143\u7d20\u4e0a\u8fdb\u884c\u4e00\u7cfb\u5217\u9ad8\u6548\u7b80\u6d01\u64cd\u4f5c\u7684API\u3002\u5b83\u5177\u6709\u4ee5\u4e0b\u7279\u70b9\u3002<\/p>\n

    \n
  1. \n
      Lambda\u8868\u8fbe\u5f0f\u548c\u51fd\u6570\u5f0f\u63a5\u53e3\uff1aStream API\u5229\u7528\u4e86Lambda\u8868\u8fbe\u5f0f\u548c\u51fd\u6570\u5f0f\u63a5\u53e3\u3002<\/ol>\n<\/li>\n<\/ol>\n

      \u4e2d\u95f4\u64cd\u4f5c\u548c\u7ec8\u7aef\u64cd\u4f5c\uff1aStream\u7684\u64cd\u4f5c\u5206\u4e3a\u4e2d\u95f4\u64cd\u4f5c\uff08\u8fdb\u884c\u8f6c\u6362\u548c\u8fc7\u6ee4\uff09\u548c\u7ec8\u7aef\u64cd\u4f5c\uff08\u751f\u6210\u7ed3\u679c\uff09\u4e24\u79cd\u7c7b\u578b\u3002<\/p>\n

      \u7ba1\u9053\u5904\u7406\uff1aStream\u7684\u64cd\u4f5c\u53ef\u4ee5\u8fde\u7eed\u5730\u4f5c\u4e3a\u7ba1\u9053\u5904\u7406\u3002<\/p>\n

      \u4ee5\u4e0b\u662f\u4f7f\u7528\u6d41API\u7684\u7b80\u5355\u4ee3\u7801\u793a\u4f8b\u3002<\/p>\n

      import<\/span> java.util.Arrays<\/span>;<\/span>\r\nimport<\/span> java.util.List<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> StreamExample<\/span> {<\/span>\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[]<\/span> args<\/span>)<\/span> {<\/span>\r\n        List<\/span><<\/span>String<\/span>><\/span> list<\/span> =<\/span> Arrays<\/span>.<\/span>asList<\/span>(<\/span>\"Apple\"<\/span>,<\/span> \"Banana\"<\/span>,<\/span> \"Cherry\"<\/span>,<\/span> \"Date\"<\/span>,<\/span> \"Elderberry\"<\/span>);<\/span>\r\n\r\n        list<\/span>.<\/span>stream<\/span>()<\/span> \/\/ Stream\u306e\u751f\u6210<\/span>\r\n            .<\/span>filter<\/span>(<\/span>s<\/span> -><\/span> s<\/span>.<\/span>length<\/span>()<\/span> ><\/span> 5<\/span>)<\/span> \/\/ \u4e2d\u9593\u64cd\u4f5c: \u6587\u5b57\u6570\u304c5\u3088\u308a\u5927\u304d\u3044\u8981\u7d20\u3092\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0<\/span>\r\n            .<\/span>map<\/span>(<\/span>String:<\/span>:<\/span>toUpperCase<\/span>)<\/span> \/\/ \u4e2d\u9593\u64cd\u4f5c: \u6587\u5b57\u5217\u3092\u5927\u6587\u5b57\u306b\u5909\u63db<\/span>\r\n            .<\/span>forEach<\/span>(<\/span>System<\/span>.<\/span>out<\/span>::<\/span>println<\/span>);<\/span> \/\/ \u7d42\u7aef\u64cd\u4f5c: \u5404\u8981\u7d20\u3092\u51fa\u529b<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\n<\/code><\/pre>\n
      \u81ea\u7531\u9009\u62e9<\/h3>\n
      Optional\u7c7b\u88ab\u8bbe\u8ba1\u4e3a\u8fd4\u56de\u53ef\u80fd\u8fd4\u56denull\u7684\u65b9\u6cd5\uff0c\u4ee3\u66ff\u8fd4\u56deOptional\u5b9e\u4f8b\u3002\u8fd9\u6837\u53ef\u4ee5\u907f\u514d\u51fa\u73b0\u7a7a\u6307\u9488\u5f02\u5e38\u3002<\/p>\n
      \u4ee5\u4e0b\u662fOptional\u7c7b\u7684\u4e00\u4e9b\u57fa\u672c\u7528\u6cd5\u3002<\/p>\n
        \n
      1. \n
          ofNullable: \u5305\u88c5\u53ef\u80fd\uff1a\u5c01\u88c5\u53ef\u80fd\u7684\u7a7a\u503c\u3002<\/ol>\n<\/li>\n<\/ol>\n
          ifPresent: \u6307\u5b9a\u5728\u503c\u5b58\u5728\u65f6\u6267\u884c\u7684\u64cd\u4f5c\u3002<\/p>\n
          orElse: \u6307\u5b9a\u5728\u503c\u4e0d\u5b58\u5728\u65f6\u8fd4\u56de\u7684\u9ed8\u8ba4\u503c\u3002<\/p>\n
          map: \u6307\u5b9a\u5728\u503c\u5b58\u5728\u65f6\u5e94\u7528\u7684\u51fd\u6570\u3002<\/p>\n
          \u4ee5\u4e0b\u662fOptional\u57fa\u672c\u4f7f\u7528\u65b9\u6cd5\u7684\u793a\u4f8b\u3002<\/p>\n
          import<\/span> java.util.Optional<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> OptionalExample<\/span> {<\/span>\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[]<\/span> args<\/span>)<\/span> {<\/span>\r\n        Optional<\/span><<\/span>String<\/span>><\/span> optional<\/span> =<\/span> Optional<\/span>.<\/span>ofNullable<\/span>(<\/span>\"Hello, World!\"<\/span>);<\/span>\r\n\r\n        optional<\/span>.<\/span>ifPresent<\/span>(<\/span>System<\/span>.<\/span>out<\/span>::<\/span>println<\/span>);<\/span> \/\/ \u5024\u304c\u5b58\u5728\u3059\u308b\u305f\u3081\u3001\"Hello, World!\"\u3092\u51fa\u529b<\/span>\r\n\r\n        String<\/span> value<\/span> =<\/span> optional<\/span>.<\/span>orElse<\/span>(<\/span>\"Default value\"<\/span>);<\/span> \/\/ \u5024\u304c\u5b58\u5728\u3059\u308b\u305f\u3081\u3001\"Hello, World!\"\u3092\u8fd4\u3057\u307e\u3059<\/span>\r\n        System<\/span>.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>value<\/span>);<\/span>\r\n\r\n        Optional<\/span><<\/span>String<\/span>><\/span> emptyOptional<\/span> =<\/span> Optional<\/span>.<\/span>empty<\/span>();<\/span>\r\n\r\n        emptyOptional<\/span>.<\/span>ifPresent<\/span>(<\/span>System<\/span>.<\/span>out<\/span>::<\/span>println<\/span>);<\/span> \/\/ \u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u305f\u3081\u3001\u4f55\u3082\u51fa\u529b\u3055\u308c\u307e\u305b\u3093<\/span>\r\n\r\n        String<\/span> defaultValue<\/span> =<\/span> emptyOptional<\/span>.<\/span>orElse<\/span>(<\/span>\"Default value\"<\/span>);<\/span> \/\/ \u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u305f\u3081\u3001\"Default value\"\u3092\u8fd4\u3057\u307e\u3059<\/span>\r\n        System<\/span>.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>defaultValue<\/span>);<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
          \u56e0\u4e3a\u5728\u516c\u53f8\u4e3e\u529e\u4e86\u4e13\u4e3aJava\u521d\u5b66\u8005\u51c6\u5907\u7684\u5b66\u4e60\u4f1a\uff0c\u5e76\u5b66\u4e60\u4e86StreamAPI\u548cOptional\uff0c\u6240\u4ee5\u6211\u5199\u4e86\u4e00\u7bc7\u6587 […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[227],"class_list":["post-31090","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-227"],"yoast_head":"\nJava\u7684Stream API\u548cOptional - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"\u5173\u4e8eJava\u7684Stream API\u548cOptional\u7684\u6280\u672f\u6587\u7ae0\" \/>\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\/zh\/blog\/java\u7684stream-api\u548coptional\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Java\u7684Stream API\u548cOptional\" \/>\n<meta property=\"og:description\" content=\"\u5173\u4e8eJava\u7684Stream API\u548cOptional\u7684\u6280\u672f\u6587\u7ae0\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/java\u7684stream-api\u548coptional\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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