{"id":31000,"date":"2023-11-13T20:01:07","date_gmt":"2023-12-04T10:08:33","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/java%e4%b8%ad%e7%9a%84flatmap%e6%98%af%e4%bb%80%e4%b9%88%ef%bc%9f\/"},"modified":"2025-08-12T21:48:25","modified_gmt":"2025-08-12T13:48:25","slug":"java%e4%b8%ad%e7%9a%84flatmap%e6%98%af%e4%bb%80%e4%b9%88%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/java%e4%b8%ad%e7%9a%84flatmap%e6%98%af%e4%bb%80%e4%b9%88%ef%bc%9f\/","title":{"rendered":"Java\u4e2d\u7684flatMap()\u662f\u4ec0\u4e48\uff1f"},"content":{"rendered":"<p>flatMap\uff08\uff09\u662fJava\u6d41\u64cd\u4f5c\uff08Stream API\uff09\u4e2d\u4f7f\u7528\u7684\u4e00\u79cd\u4e2d\u95f4\u64cd\u4f5c\u3002<\/p>\n<p>flatMap\uff08\uff09\u65b9\u6cd5\u5c06\u6d41\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u8f6c\u6362\u4e3a\u53e6\u4e00\u4e2a\u6d41\uff0c\u5e76\u5c06\u8fd9\u4e9b\u6d41\u5408\u5e76\u6210\u4e00\u4e2a\u5355\u4e00\u7684\u6d41\u3002<\/p>\n<p>flatMap() \u65b9\u6cd5\u4f3c\u4e4e\u7528\u4e8e\u5c06\u6bcf\u4e2a\u5143\u7d20\u8f6c\u6362\u4e3a\u7531\u591a\u4e2a\u5143\u7d20\u7ec4\u6210\u7684\u65b0\u6d41\u3002<br \/>\n\u5b83\u5c06\u6620\u5c04\u51fd\u6570\u5e94\u7528\u4e8e\u6bcf\u4e2a\u5143\u7d20\uff0c\u5e76\u5c06\u7ed3\u679c\u6241\u5e73\u5316\u4ee5\u5408\u5e76\u4e3a\u5355\u4e00\u6d41\u3002<\/p>\n<p>\u6837\u672c\u2193<\/p>\n<pre class=\"post-pre\"><code><span class=\"nc\">List<\/span><span class=\"o\">&lt;<\/span><span class=\"nc\">List<\/span><span class=\"o\">&lt;<\/span><span class=\"nc\">Integer<\/span><span class=\"o\">&gt;&gt;<\/span> <span class=\"n\">nestedList<\/span> <span class=\"o\">=<\/span> <span class=\"nc\">Arrays<\/span><span class=\"o\">.<\/span><span class=\"na\">asList<\/span><span class=\"o\">(<\/span>\r\n    <span class=\"nc\">Arrays<\/span><span class=\"o\">.<\/span><span class=\"na\">asList<\/span><span class=\"o\">(<\/span><span class=\"mi\">1<\/span><span class=\"o\">,<\/span> <span class=\"mi\">2<\/span><span class=\"o\">,<\/span> <span class=\"mi\">3<\/span><span class=\"o\">),<\/span>\r\n    <span class=\"nc\">Arrays<\/span><span class=\"o\">.<\/span><span class=\"na\">asList<\/span><span class=\"o\">(<\/span><span class=\"mi\">4<\/span><span class=\"o\">,<\/span> <span class=\"mi\">5<\/span><span class=\"o\">,<\/span> <span class=\"mi\">6<\/span><span class=\"o\">),<\/span>\r\n    <span class=\"nc\">Arrays<\/span><span class=\"o\">.<\/span><span class=\"na\">asList<\/span><span class=\"o\">(<\/span><span class=\"mi\">7<\/span><span class=\"o\">,<\/span> <span class=\"mi\">8<\/span><span class=\"o\">,<\/span> <span class=\"mi\">9<\/span><span class=\"o\">)<\/span>\r\n<span class=\"o\">);<\/span>\r\n\r\n<span class=\"nc\">List<\/span><span class=\"o\">&lt;<\/span><span class=\"nc\">Integer<\/span><span class=\"o\">&gt;<\/span> <span class=\"n\">flattenedList<\/span> <span class=\"o\">=<\/span> <span class=\"n\">nestedList<\/span><span class=\"o\">.<\/span><span class=\"na\">stream<\/span><span class=\"o\">()<\/span>\r\n   <span class=\"o\">.<\/span><span class=\"na\">flatMap<\/span><span class=\"o\">(<\/span><span class=\"nl\">Collection:<\/span><span class=\"o\">:<\/span><span class=\"n\">stream<\/span><span class=\"o\">)<\/span>\r\n   <span class=\"o\">.<\/span><span class=\"na\">collect<\/span><span class=\"o\">(<\/span><span class=\"nc\">Collectors<\/span><span class=\"o\">.<\/span><span class=\"na\">toList<\/span><span class=\"o\">());<\/span>\r\n\r\n<span class=\"nc\">System<\/span><span class=\"o\">.<\/span><span class=\"na\">out<\/span><span class=\"o\">.<\/span><span class=\"na\">println<\/span><span class=\"o\">(<\/span><span class=\"n\">flattenedList<\/span><span class=\"o\">);<\/span>\r\n<\/code><\/pre>\n<p>\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u6709\u4e00\u4e2a\u5d4c\u5957\u7684\u6574\u6570\u5217\u8868nestedList\u3002\u6211\u4eec\u4f7f\u7528flatMap(Collection::stream)\u6765\u5c06\u6bcf\u4e2a\u5217\u8868\u5c55\u5e73\uff0c\u5e76\u751f\u6210\u4e00\u4e2a\u5355\u4e00\u7684\u6574\u6570\u5217\u8868flattenedList\u3002<\/p>\n<p>\u4ee5\u4e0b\u662f\u8f93\u51fa\u7ed3\u679c\u2193<\/p>\n<pre class=\"post-pre\"><code>[1, 2, 3, 4, 5, 6, 7, 8, 9]\r\n<\/code><\/pre>\n<p>\u4f7f\u7528flatMap()\u51fd\u6570\uff0c\u53ef\u4ee5\u5c06\u5d4c\u5957\u5217\u8868\u7684\u6bcf\u4e2a\u5143\u7d20\u5408\u5e76\u4e3a\u5355\u4e2a\u5143\u7d20\uff0c\u5e76\u5c06\u5176\u8f6c\u5316\u4e3a\u5e73\u5766\u5316\u7684\u5355\u4e00\u6d41\u3002<\/p>\n<p>flatMap() \u662f\u4e00\u4e2a\u65b9\u4fbf\u7684\u65b9\u6cd5\uff0c\u7528\u4e8e\u5c06\u5143\u7d20\u6241\u5e73\u5316\u3002\u7279\u522b\u9002\u7528\u4e8e\u5d4c\u5957\u7684\u5217\u8868\u6216\u6620\u5c04\u7b49\u60c5\u51b5\u4e0b\u3002<\/p>\n<p>\u592a\u96be\u5566\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>flatMap\uff08\uff09\u662fJava\u6d41\u64cd\u4f5c\uff08Stream API\uff09\u4e2d\u4f7f\u7528\u7684\u4e00\u79cd\u4e2d\u95f4\u64cd\u4f5c\u3002 flatMap\uff08\uff09\u65b9\u6cd5\u5c06\u6d41\u4e2d [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[227],"class_list":["post-31000","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-227"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ 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