{"id":202874,"date":"2025-05-22T08:08:49","date_gmt":"2025-05-22T00:08:49","guid":{"rendered":"https:\/\/server.hk\/cnblog\/202874\/"},"modified":"2025-05-22T08:08:49","modified_gmt":"2025-05-22T00:08:49","slug":"java%e5%87%bd%e6%95%b0%e5%bc%8f%e7%bc%96%e7%a8%8b%e4%b8%ad%e7%9a%84lambda%e8%a1%a8%e8%be%be%e5%bc%8f%e4%b8%8e%e9%ab%98%e9%98%b6%e5%87%bd%e6%95%b0%e7%9a%84%e5%85%b3%e7%b3%bb%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/202874\/","title":{"rendered":"Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684lambda\u8868\u8fbe\u5f0f\u4e0e\u9ad8\u9636\u51fd\u6570\u7684\u5173\u7cfb\uff1f"},"content":{"rendered":"

<\/b> <\/p>\n

Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684lambda\u8868\u8fbe\u5f0f\u4e0e\u9ad8\u9636\u51fd\u6570\u7684\u5173\u7cfb\uff1f<\/h1>\n

\u5c0f\u4f19\u4f34\u4eec\u5bf9\u6587\u7ae0\u7f16\u7a0b\u611f\u5174\u8da3\u5417\uff1f\u662f\u5426\u6b63\u5728\u5b66\u4e60\u76f8\u5173\u77e5\u8bc6\u70b9\uff1f\u5982\u679c\u662f\uff0c\u90a3\u4e48\u672c\u6587\u300aJava\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684lambda\u8868\u8fbe\u5f0f\u4e0e\u9ad8\u9636\u51fd\u6570\u7684\u5173\u7cfb\uff1f\u300b\uff0c\u5c31\u5f88\u9002\u5408\u4f60\uff0c\u672c\u7bc7\u6587\u7ae0\u8bb2\u89e3\u7684\u77e5\u8bc6\u70b9\u4e3b\u8981\u5305\u62ec\u3002\u5728\u4e4b\u540e\u7684\u6587\u7ae0\u4e2d\u4e5f\u4f1a\u591a\u591a\u5206\u4eab\u76f8\u5173\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff01<\/p>\n

<\/p>\n

Java \u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684 Lambda \u8868\u8fbe\u5f0f\u4e0e\u9ad8\u9636\u51fd\u6570<\/strong><\/p>\n

\u7b80\u4ecb<\/strong><\/p>\n

\u5728 Java \u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\uff0clambda \u8868\u8fbe\u5f0f\u548c\u9ad8\u9636\u51fd\u6570\u662f\u4e24\u4e2a\u5bc6\u5207\u76f8\u5173\u7684\u6982\u5ff5\u3002lambda \u8868\u8fbe\u5f0f\u5141\u8bb8\u6211\u4eec\u521b\u5efa\u533f\u540d\u51fd\u6570\uff0c\u800c\u9ad8\u9636\u51fd\u6570\u5141\u8bb8\u6211\u4eec\u64cd\u4f5c\u51fd\u6570\u4f5c\u4e3a\u53c2\u6570\u6216\u8fd4\u56de\u7c7b\u578b\u3002\u672c\u6587\u5c06\u63a2\u8ba8\u8fd9\u4e24\u8005\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u5e76\u63d0\u4f9b\u5b9e\u6218\u6848\u4f8b\u3002<\/p>\n

Lambda \u8868\u8fbe\u5f0f<\/strong><\/p>\n

Lambda \u8868\u8fbe\u5f0f\u662f\u4e00\u79cd\u7b80\u5316\u7684\u533f\u540d\u51fd\u6570\uff0c\u5141\u8bb8\u6211\u4eec\u4f7f\u7528\u66f4\u7b80\u6d01\u7684\u8bed\u6cd5\u6765\u5b9a\u4e49\u51fd\u6570\u3002\u5b83\u4eec\u53ef\u4ee5\u4f7f\u7528 -><\/code> \u8fd0\u7b97\u7b26\u7f16\u5199\uff0c\u5b83\u5c06\u5de6\u8fb9\u7684\u53c2\u6570\u4e0e\u53f3\u8fb9\u7684\u51fd\u6570\u4f53\u5206\u9694\u5f00\u6765\u3002\u4f8b\u5982\uff1a<\/p>\n

(x, y) -> x + y;<\/pre>\n
\u8fd9\u4e2a lambda \u8868\u8fbe\u5f0f\u5b9a\u4e49\u4e86\u4e00\u4e2a\u6709\u4e24\u4e2a\u53c2\u6570\uff08x \u548c y\uff09\u7684\u51fd\u6570\uff0c\u5b83\u8fd4\u56de\u5b83\u4eec\u7684\u548c\u3002<\/p>\n
\u9ad8\u9636\u51fd\u6570<\/strong><\/p>\n
\u9ad8\u9636\u51fd\u6570\u662f\u4e00\u79cd\u51fd\u6570\uff0c\u5b83\u53ef\u4ee5\u5c06\u5176\u4ed6\u51fd\u6570\u4f5c\u4e3a\u53c2\u6570\u63a5\u6536\uff0c\u6216\u8005\u8fd4\u56de\u51fd\u6570\u4f5c\u4e3a\u7ed3\u679c\u3002\u4e00\u4e9b\u5e38\u89c1\u7684\u4f8b\u5b50\u662f map()<\/code>\u3001filter()<\/code> \u548c reduce()<\/code>\u3002<\/p>\n
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);\n\n\/\/ \u4f7f\u7528 map() \u5c06\u6bcf\u4e2a\u6570\u5b57\u5e73\u65b9\nList<Integer> squaredNumbers = numbers.map(n -> n * n);\n\n\/\/ \u4f7f\u7528 filter() \u8fc7\u6ee4\u5947\u6570\nList<Integer> oddNumbers = numbers.filter(n -> n % 2 == 1);\n\n\/\/ \u4f7f\u7528 reduce() \u8ba1\u7b97\u6570\u5b57\u7684\u548c\nint sum = numbers.reduce(0, (acc, n) -> acc + n);<\/pre>\n
\u9ad8\u9636\u51fd\u6570\u4e0e Lambda \u8868\u8fbe\u5f0f\u7684\u5173\u7cfb<\/strong><\/p>\n
\u9ad8\u9636\u51fd\u6570\u548c lambda \u8868\u8fbe\u5f0f\u53ef\u4ee5\u5f88\u597d\u5730\u7ed3\u5408\u4f7f\u7528\uff0c\u4f7f\u51fd\u6570\u5f0f\u7f16\u7a0b\u66f4\u4e3a\u7b80\u6d01\u6e05\u6670\u3002lambda \u8868\u8fbe\u5f0f\u53ef\u4ee5\u4e3a\u9ad8\u9636\u51fd\u6570\u63d0\u4f9b\u51fd\u6570\u53c2\u6570\uff0c\u4ece\u800c\u907f\u514d\u4e86\u521b\u5efa\u548c\u4f20\u9012\u989d\u5916\u7684\u533f\u540d\u7c7b\u6216\u5185\u90e8\u7c7b\u3002<\/p>\n
\u5b9e\u6218\u6848\u4f8b<\/strong><\/p>\n
\u8ba1\u7b97\u5546\u573a\u7684\u603b\u9500\u552e\u989d<\/strong><\/p>\n
\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a Sales<\/code> \u7c7b\uff0c\u5176\u4e2d\u5b58\u50a8\u4e86\u6bcf\u7b14\u9500\u552e\u7684\u65e5\u671f\u548c\u91d1\u989d\u3002\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u9ad8\u9636\u51fd\u6570\u548c lambda \u8868\u8fbe\u5f0f\u6765\u8ba1\u7b97\u7279\u5b9a\u65e5\u671f\u8303\u56f4\u5185\u7684\u603b\u9500\u552e\u989d\uff1a<\/p>\n
import java.time.LocalDate;\nimport java.util.List;\n\nclass Sales {\n\n    private LocalDate date;\n    private double amount;\n\n    public Sales(LocalDate date, double amount) {\n        this.date = date;\n        this.amount = amount;\n    }\n\n    public LocalDate getDate() {\n        return date;\n    }\n\n    public double getAmount() {\n        return amount;\n    }\n}\n\npublic class SalesCalculator {\n\n    public static double calculateTotalSales(List<Sales> sales, LocalDate startDate, LocalDate endDate) {\n        return sales\n                .stream()\n                .filter(sale -> sale.getDate().isAfter(startDate) && sale.getDate().isBefore(endDate))\n                .reduce(0.0, (total, sale) -> total + sale.getAmount());\n    }\n\n    public static void main(String[] args) {\n        List<Sales> sales = List.of(\n                new Sales(LocalDate.of(2023, 1, 1), 100.0),\n                new Sales(LocalDate.of(2023, 1, 5), 200.0),\n                new Sales(LocalDate.of(2023, 2, 1), 300.0)\n        );\n\n        double totalSales = calculateTotalSales(sales, LocalDate.of(2023, 1, 1), LocalDate.of(2023, 1, 31));\n\n        System.out.println(\"Total sales: $\" + totalSales);\n        \/\/ \u8f93\u51fa: Total sales: $300.0\n    }\n}<\/pre>\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0ccalculateTotalSales()<\/code> \u65b9\u6cd5\u4f7f\u7528\u9ad8\u9636\u51fd\u6570 stream()<\/code>, filter()<\/code> \u548c reduce()<\/code> \u6765\u8ba1\u7b97\u7279\u5b9a\u65e5\u671f\u8303\u56f4\u5185\u7684\u603b\u9500\u552e\u989d\u3002lambda \u8868\u8fbe\u5f0f\u7528\u4e8e\u6307\u5b9a filter()<\/code> \u7684\u8fc7\u6ee4\u6761\u4ef6\u548c reduce()<\/code> \u7684\u7d2f\u52a0\u51fd\u6570\u3002<\/p>\n
\u4eca\u5929\u5173\u4e8e\u300aJava\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684lambda\u8868\u8fbe\u5f0f\u4e0e\u9ad8\u9636\u51fd\u6570\u7684\u5173\u7cfb\uff1f\u300b\u7684\u5185\u5bb9\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\uff0c\u5982\u679c\u6709\u4ec0\u4e48\u7591\u95ee\u6216\u8005\u5efa\u8bae\uff0c\u53ef\u4ee5\u5728\u516c\u4f17\u53f7\u4e0b\u591a\u591a\u56de\u590d\u4ea4\u6d41\uff1b\u6587\u4e2d\u82e5\u6709\u4e0d\u6b63\u4e4b\u5904\uff0c\u4e5f\u5e0c\u671b\u56de\u590d\u7559\u8a00\u4ee5\u544a\u77e5\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
Java\u51fd\u6570\u5f0f\u7f16\u7a0b\u4e2d\u7684lambd...<\/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-202874","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202874","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=202874"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202874\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=202874"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=202874"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=202874"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}