{"id":203025,"date":"2025-05-22T12:45:03","date_gmt":"2025-05-22T04:45:03","guid":{"rendered":"https:\/\/server.hk\/cnblog\/203025\/"},"modified":"2025-05-22T12:45:03","modified_gmt":"2025-05-22T04:45:03","slug":"%e5%9c%a8java%e5%87%bd%e6%95%b0%e5%bc%8f%e7%bc%96%e7%a8%8b%e4%b8%ad%e4%bd%bf%e7%94%a8stream-api%e5%ae%9e%e7%8e%b0%e5%b9%b6%e8%a1%8c%e8%ae%a1%e7%ae%97%e7%9a%84%e6%9c%80%e4%bd%b3%e5%ae%9e%e8%b7%b5","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/203025\/","title":{"rendered":"\u5728Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u4f7f\u7528Stream API\u5b9e\u73b0\u5e76\u884c\u8ba1\u7b97\u7684\u6700\u4f73\u5b9e\u8df5"},"content":{"rendered":"<p><b><\/b>     <\/p>\n<h1>\u5728Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u4f7f\u7528Stream API\u5b9e\u73b0\u5e76\u884c\u8ba1\u7b97\u7684\u6700\u4f73\u5b9e\u8df5<\/h1>\n<p>\u4eca\u65e5\u4e0d\u80af\u57cb\u5934\uff0c\u660e\u65e5\u4f55\u4ee5\u62ac\u5934\uff01\u6bcf\u65e5\u4e00\u53e5\u52aa\u529b\u81ea\u5df1\u7684\u8bdd\u54c8\u54c8~\u54c8\u55bd\uff0c\u4eca\u5929\u6211\u5c06\u7ed9\u5927\u5bb6\u5e26\u6765\u4e00\u7bc7<span style=\"color: #FF6600;, Helvetica, Arial, sans-serif;font-size: 14px;background-color: #FFFFFF\">\u300a\u5728Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u4f7f\u7528Stream API\u5b9e\u73b0\u5e76\u884c\u8ba1\u7b97\u7684\u6700\u4f73\u5b9e\u8df5\u300b<\/span>\uff0c\u4e3b\u8981\u5185\u5bb9\u662f\u8bb2\u89e3<span style=\"color: #FF6600;, Helvetica, Arial, sans-serif;font-size: 14px;background-color: #FFFFFF\"><\/span>\u7b49\u7b49\uff0c\u611f\u5174\u8da3\u7684\u670b\u53cb\u53ef\u4ee5\u6536\u85cf\u6216\u8005\u6709\u66f4\u597d\u7684\u5efa\u8bae\u5728\u8bc4\u8bba\u63d0\u51fa\uff0c\u6211\u90fd\u4f1a\u8ba4\u771f\u770b\u7684\uff01\u5927\u5bb6\u4e00\u8d77\u8fdb\u6b65\uff0c\u4e00\u8d77\u5b66\u4e60\uff01<\/p>\n<p>Java Stream API \u5e76\u884c\u8ba1\u7b97\u6700\u4f73\u5b9e\u8df5\uff1a\u786e\u5b9a\u9002\u7528\u7684\u573a\u666f\uff1a\u8003\u8651\u64cd\u4f5c\u662f\u5426\u9002\u5408\u5e76\u884c\u5316\uff0c\u5927\u6570\u636e\u5904\u7406\u66f4\u9002\u5408\u3002\u8bbe\u5b9a\u5408\u9002\u5e76\u884c\u5ea6\uff1a\u6839\u636e\u5904\u7406\u5668\u5185\u6838\u6570\u786e\u5b9a\u6700\u4f73\u7ebf\u7a0b\u6570\u3002\u907f\u514d\u72b6\u6001\u5171\u4eab\uff1a\u4f7f\u7528\u65e0\u72b6\u6001\u51fd\u6570\u5f0f\u64cd\u4f5c\uff0c\u6216\u4f7f\u7528\u540c\u6b65\u673a\u5236\u4fdd\u62a4\u72b6\u6001\u3002\u4f7f\u7528\u6d41\u7684\u7ec8\u6b62\u64cd\u4f5c\uff1a\u7ec8\u6b62\u64cd\u4f5c\u89e6\u53d1\u5e76\u884c\u6267\u884c\u3002\u907f\u514d\u86ee\u529b\u5e76\u884c\u5316\uff1a\u8c28\u614e\u9009\u62e9\u5e76\u884c\u5316\u64cd\u4f5c\uff0c\u987a\u5e8f\u6267\u884c\u53ef\u80fd\u66f4\u6709\u6548\u7387\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241027\/1730023237671e0f45bd21d.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u5728 Java \u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u4f7f\u7528 Stream API \u5b9e\u73b0\u5e76\u884c\u8ba1\u7b97\u7684\u6700\u4f73\u5b9e\u8df5<\/strong><\/p>\n<p>Stream API \u662f Java \u4e2d\u4e00\u4e2a\u5f3a\u5927\u7684\u5de5\u5177\uff0c\u5b83\u5141\u8bb8\u60a8\u4ee5\u58f0\u660e\u5f0f\u65b9\u5f0f\u64cd\u4f5c\u6570\u636e\u6d41\u3002\u5176\u5e76\u884c\u7279\u6027\u53ef\u8ba9\u60a8\u5728\u591a\u4e2a\u5904\u7406\u5668\u5185\u6838\u4e0a\u5206\u5e03\u5904\u7406\uff0c\u4ece\u800c\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd\u3002<\/p>\n<p><strong>\u6700\u4f73\u5b9e\u8df5\uff1a<\/strong><\/p>\n<ul>\n<li><strong>\u786e\u5b9a\u9002\u7528\u7684\u573a\u666f\uff1a<\/strong>\u5e76\u975e\u6240\u6709\u64cd\u4f5c\u90fd\u9002\u5408\u5e76\u884c\u5316\u3002\u68c0\u67e5\u60a8\u7684\u4ee3\u7801\uff0c\u627e\u51fa\u53ef\u4ee5\u4ece\u5e76\u884c\u5904\u7406\u4e2d\u53d7\u76ca\u7684\u90e8\u5206\u3002\u901a\u5e38\uff0c\u5904\u7406\u5927\u91cf\u6570\u636e\u7684\u64cd\u4f5c\u66f4\u9002\u5408\u5e76\u884c\u5316\u3002<\/li>\n<li><strong>\u4f7f\u7528\u5408\u9002\u7684\u5e76\u884c\u5ea6\uff1a<\/strong>\u5e76\u884c\u5ea6\u5b9a\u4e49\u4e86\u7528\u4e8e\u6267\u884c\u64cd\u4f5c\u7684\u7ebf\u7a0b\u6570\u3002\u786e\u5b9a\u6700\u4f73\u5e76\u884c\u5ea6\u53ef\u80fd\u9700\u8981\u4e00\u4e9b\u5b9e\u9a8c\u3002\u4f5c\u4e3a\u4e00\u4e2a\u8d77\u70b9\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528\u673a\u5668\u7684\u5904\u7406\u5668\u5185\u6838\u6570\u3002<\/li>\n<li><strong>\u907f\u514d\u72b6\u6001\u5171\u4eab\uff1a<\/strong>\u5e76\u884c\u64cd\u4f5c\u4e2d\u53d8\u91cf\u5171\u4eab\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6570\u636e\u4e0d\u4e00\u81f4\u3002\u786e\u4fdd\u60a8\u7684\u51fd\u6570\u5f0f\u64cd\u4f5c\u662f\u65e0\u72b6\u6001\u7684\uff0c\u6216\u8005\u4f7f\u7528\u6b63\u786e\u7684\u540c\u6b65\u673a\u5236\u6765\u4fdd\u62a4\u72b6\u6001\u3002<\/li>\n<li><strong>\u4f7f\u7528\u6d41\u7684\u7ec8\u6b62\u64cd\u4f5c\uff1a<\/strong>\u7ec8\u6b62\u64cd\u4f5c\uff0c\u4f8b\u5982 <code>forEach<\/code> \u6216 <code>collect<\/code>\uff0c\u4f1a\u89e6\u53d1\u5e76\u884c\u64cd\u4f5c\u7684\u5b9e\u9645\u6267\u884c\u3002\u5728\u7ec8\u6b62\u64cd\u4f5c\u4e4b\u524d\uff0c\u4e0d\u4f1a\u6267\u884c\u4efb\u4f55\u5e76\u884c\u5904\u7406\u3002<\/li>\n<li><strong>\u907f\u514d\u86ee\u529b\u5e76\u884c\u5316\uff1a<\/strong>\u5e76\u975e\u6bcf\u4e2a\u64cd\u4f5c\u90fd\u5e94\u8be5\u5e76\u884c\u5316\u3002\u6709\u65f6\uff0c\u987a\u5e8f\u6267\u884c\u53ef\u80fd\u66f4\u6709\u6548\u7387\u3002\u8c28\u614e\u9009\u62e9\u8981\u5e76\u884c\u5316\u7684\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n<p><strong>\u5b9e\u6218\u6848\u4f8b\uff1a<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u5927\u5b66\u751f\u5217\u8868\uff0c\u6bcf\u4e2a\u5b66\u751f\u90fd\u6709\u4e00\u4e2a\u540d\u5b57\u548c\u5206\u6570\u3002\u6211\u4eec\u5e0c\u671b\u8ba1\u7b97\u51fa\u603b\u5e73\u5747\u5206\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b Stream API \u4ee3\u7801\u6765\u5b9e\u73b0\u6b64\u76ee\u7684\uff1a<\/p>\n<pre>\/\/ \u83b7\u53d6\u5b66\u751f\u5217\u8868\nList&lt;Student&gt; students = ...;\n\n\/\/ \u4f7f\u7528\u5e76\u884c\u6d41\u8ba1\u7b97\u603b\u5e73\u5747\u5206\ndouble avgScore = students.parallelStream()\n    .mapToDouble(Student::getScore)\n    .average()\n    .getAsDouble();\n\n\/\/ \u8f93\u51fa\u5e73\u5747\u5206\nSystem.out.println(\"\u5e73\u5747\u5206\uff1a\" + avgScore);<\/pre>\n<p>\u6b64\u4ee3\u7801\u4f7f\u7528 <code>parallelStream()<\/code> \u65b9\u6cd5\u521b\u5efa\u4e86\u4e00\u4e2a\u5e76\u884c\u6d41\u3002\u7136\u540e\uff0c\u5b83\u4f7f\u7528 <code>mapToDouble()<\/code> \u5c06\u6d41\u8f6c\u6362\u4e3a\u4e00\u4e2a Double \u6d41\uff0c\u5bf9\u6bcf\u4e2a\u5b66\u751f\u5206\u6570\u5e94\u7528\u8f6c\u6362\u3002\u6700\u540e\uff0c\u5b83\u4f7f\u7528 <code>average()<\/code> \u8ba1\u7b97\u6d41\u4e2d\u6570\u5b57\u7684\u5e73\u5747\u503c\u3002<\/p>\n<p>\u4eca\u5929\u5e26\u5927\u5bb6\u4e86\u89e3\u4e86\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u5e0c\u671b\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff1b\u5173\u4e8e\u6587\u7ae0\u7684\u6280\u672f\u77e5\u8bc6\u6211\u4eec\u4f1a\u4e00\u70b9\u70b9\u6df1\u5165\u4ecb\u7ecd\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u516c\u4f17\u53f7\uff0c\u4e00\u8d77\u5b66\u4e60\u7f16\u7a0b~<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u4f7f\u7528Str&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-203025","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/203025","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=203025"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/203025\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=203025"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=203025"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=203025"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}