{"id":1421,"date":"2025-09-29T14:35:42","date_gmt":"2025-09-29T06:35:42","guid":{"rendered":"http:\/\/www.cmd137blog.top\/?p=1421"},"modified":"2025-09-29T14:35:44","modified_gmt":"2025-09-29T06:35:44","slug":"%e4%bd%bf%e7%94%a8-java-stream-linkedhashmap-%e6%8c%89%e6%97%a5%e6%9c%9f%e6%8e%92%e5%ba%8f-map-%e5%ae%9e%e6%88%98%e4%b8%8e%e5%8e%9f%e7%90%86","status":"publish","type":"post","link":"http:\/\/www.cmd137blog.top\/?p=1421","title":{"rendered":"\u4f7f\u7528 Java Stream + LinkedHashMap \u6309\u65e5\u671f\u6392\u5e8f Map \u2014\u2014 \u5b9e\u6218\u4e0e\u539f\u7406"},"content":{"rendered":"\n

\u5728\u4e1a\u52a1\u5f00\u53d1\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u62ff\u5230\u8fd9\u6837\u4e00\u7c7b\u6570\u636e\uff1a<\/p>\n\n\n\n

{\n    \"supplierId\": 56,\n    \"supplierName\": \"\u96c4\u5b89\u94c1\u5efa\u96c6\u56e2\",\n    \"dailyInAmount\": {\n        \"2025-09-14\": 170.00,\n        \"2025-09-13\": 180.00,\n        \"2025-09-12\": 190.00,\n        \"2025-09-11\": 200.00,\n        \"2025-09-18\": 130.00,\n        ...\n    }\n}\n<\/code><\/pre>\n\n\n\n
\u8fd9\u662f\u4e00\u4e2a Map<String, BigDecimal><\/code>\uff08key \u662f\u65e5\u671f\u5b57\u7b26\u4e32\uff0cvalue \u662f\u91d1\u989d\uff09\u3002\u7531\u4e8e HashMap<\/code> \u7684\u904d\u5386\u987a\u5e8f\u662f\u65e0\u5e8f\u7684<\/strong>\uff0c\u524d\u7aef\u62ff\u5230\u7684 dailyInAmount<\/code> \u4f1a\u662f\u4e71\u5e8f\u7684\u65e5\u671f\u3002<\/p>\n\n\n\n
\u5b9e\u9645\u6548\u679c\u53ef\u80fd\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
\"2025-09-14\": 170.00,\n\"2025-09-13\": 180.00,\n\"2025-09-30\": 10.00,\n...\n<\/code><\/pre>\n\n\n\n
\u800c\u6211\u4eec\u7684\u9700\u6c42\u662f\uff1a\u6309\u65e5\u671f\u5347\u5e8f\u8f93\u51fa<\/strong>\uff0c\u8fd9\u6837\u524d\u7aef\u5c55\u793a\u5c31\u662f\u6709\u5e8f\u7684\u65f6\u95f4\u8f74\uff1a<\/p>\n\n\n\n
\"2025-09-01\": 300.00,\n\"2025-09-02\": 290.00,\n\"2025-09-03\": 280.00,\n...\n<\/code><\/pre>\n\n\n\n
Stream \u89e3\u51b3\u65b9\u6848<\/h3>\n\n\n\n
Java 8 \u4e4b\u540e\u6709\u4e86 Stream API<\/code>\uff0c\u53ef\u4ee5\u5f88\u4f18\u96c5\u5730\u5b8c\u6210\u8fd9\u79cd\u201c\u5bf9 Map \u6309\u952e\u6392\u5e8f\u5e76\u6536\u96c6\u201d\u7684\u9700\u6c42\uff1a<\/p>\n\n\n\n
\/\/ dailyAmount: Map<String, BigDecimal> \u539f\u59cb\u6570\u636e\nMap<String, BigDecimal> sortedDailyAmount = dailyAmount.entrySet().stream()\n        .sorted(Map.Entry.comparingByKey()) \/\/ \u6309 key \u6392\u5e8f\n        .collect(Collectors.toMap(\n                Map.Entry::getKey,         \/\/ key \u63d0\u53d6\u5668\n                Map.Entry::getValue,       \/\/ value \u63d0\u53d6\u5668\n                (e1, e2) -> e1,            \/\/ \u51b2\u7a81\u65f6\u53d6\u7b2c\u4e00\u4e2a\uff08\u4e00\u822c\u4e0d\u4f1a\u51b2\u7a81\uff09\n                LinkedHashMap::new         \/\/ \u6700\u7ec8 Map \u7c7b\u578b\uff1a\u6309\u63d2\u5165\u987a\u5e8f\n        ));\n\nplanVO.setDailyInAmount(sortedDailyAmount);\n<\/code><\/pre>\n\n\n\n
\u6838\u5fc3\u70b9\uff1a<\/p>\n\n\n\n
    \n
  • entrySet().stream()<\/code>\uff1aMap<\/code> \u672c\u8eab\u4e0d\u662f Collection<\/code>\uff0c\u6ca1\u6709 stream()<\/code>\uff1b\u8981\u6d41\u5f0f\u5904\u7406\u5fc5\u987b\u5148\u53d6 entrySet()<\/code>\u3002<\/li>\n\n\n\n
  • .sorted(Map.Entry.comparingByKey())<\/code>\uff1a\u5bf9 entry \u6d41\u6309 key \u81ea\u7136\u987a\u5e8f\u6392\u5e8f\u3002\u8fd9\u91cc key \u662f yyyy-MM-dd<\/code> \u683c\u5f0f\u7684\u5b57\u7b26\u4e32\uff0c\u5b57\u5178\u5e8f = \u65f6\u95f4\u987a\u5e8f\u3002<\/li>\n\n\n\n
  • Collectors.toMap(...)<\/code> \u7684 4 \u4e2a\u53c2\u6570\uff1a\n
      \n
    1. key \u6620\u5c04\u5668<\/li>\n\n\n\n
    2. value \u6620\u5c04\u5668<\/li>\n\n\n\n
    3. \u51b2\u7a81\u5408\u5e76\u7b56\u7565<\/li>\n\n\n\n
    4. \u6700\u7ec8 Map \u7c7b\u578b<\/li>\n<\/ol>\n<\/li>\n\n\n\n
    5. \u9009\u62e9 LinkedHashMap<\/code> \u662f\u4e3a\u4e86\u4fdd\u7559\u63d2\u5165\u987a\u5e8f<\/strong>\uff08\u6211\u4eec\u5df2\u7ecf\u6309\u65e5\u671f\u6392\u5e8f\u540e\u518d\u63d2\u5165\uff0c\u6240\u4ee5\u8fed\u4ee3\u5c31\u662f\u65e5\u671f\u987a\u5e8f\uff09\u3002<\/li>\n<\/ul>\n\n\n\n
      \u6548\u679c<\/h3>\n\n\n\n
      \u7ecf\u8fc7\u8fd9\u6bb5\u4ee3\u7801\u5904\u7406\u540e\uff0c\u524d\u7aef\u8fd4\u56de\u7684\u6570\u636e\u5c31\u662f\u6309\u65e5\u671f\u987a\u5e8f\u6392\u5217\u7684\uff1a<\/p>\n\n\n\n
      \"dailyInAmount\": {\n    \"2025-09-01\": 300.00,\n    \"2025-09-02\": 290.00,\n    \"2025-09-03\": 280.00,\n    \"2025-09-04\": 270.00,\n    ...\n}\n<\/code><\/pre>\n\n\n\n
      \u5e38\u89c1\u53d8\u4f53<\/h3>\n\n\n\n
        \n
      1. \u6309 value \u6392\u5e8f<\/strong>\uff1a .sorted(Map.Entry.<String,BigDecimal>comparingByValue().reversed())<\/code><\/li>\n\n\n\n
      2. \u6309\u771f\u5b9e\u65f6\u95f4\u6392\u5e8f<\/strong>\uff08\u5b57\u7b26\u4e32\u4e0d\u89c4\u5219\u65f6\uff09\uff1a DateTimeFormatter dtf = DateTimeFormatter.ofPattern(\"yyyy\/MM\/dd\"); .sorted(Comparator.comparing(e -> LocalDate.parse(e.getKey(), dtf)))<\/code><\/li>\n\n\n\n
      3. \u7528 TreeMap \u7b80\u5316<\/strong>\uff1a Map<String,BigDecimal> sorted = new TreeMap<>(dailyAmount);<\/code><\/li>\n<\/ol>\n\n\n\n
        TreeMap \u4f1a\u81ea\u52a8\u6309 key \u6392\u5e8f\uff0c\u4e0d\u8fc7\u8fd4\u56de\u7684\u662f SortedMap<\/code>\uff0c\u4e0d\u662f\u6309\u63d2\u5165\u987a\u5e8f\u7684 LinkedHashMap<\/code>\uff1b\u89c6\u9700\u6c42\u9009\u62e9\u3002<\/p>\n\n\n\n
        \u603b\u7ed3<\/h3>\n\n\n\n
          \n
        • Map<\/code> \u672c\u8eab\u6ca1\u6709 stream()<\/code>\uff0c\u8981\u5904\u7406\u952e\u503c\u5bf9\u8bf7\u7528 entrySet().stream()<\/code>\u3002<\/li>\n\n\n\n
        • sorted + Collectors.toMap<\/code> \u662f Java 8 \u6d41\u5904\u7406 Map \u6392\u5e8f\u7684\u7ecf\u5178\u7528\u6cd5\u3002<\/li>\n\n\n\n
        • \u6307\u5b9a LinkedHashMap::new<\/code> \u53ef\u4ee5\u8ba9\u7ed3\u679c\u6309\u6211\u4eec\u6392\u5e8f\u540e\u7684\u987a\u5e8f\u8fed\u4ee3\u3002<\/li>\n\n\n\n
        • \u5bf9\u65e5\u671f\u3001\u91d1\u989d\u8fd9\u7c7b\u4e1a\u52a1\u6570\u636e\uff0c\u524d\u7aef\u5c55\u793a\u901a\u5e38\u8981\u6c42\u6709\u5e8f\uff0c\u8fd9\u5c31\u662f\u8fd9\u79cd\u7528\u6cd5\u7684\u5178\u578b\u573a\u666f\u3002<\/li>\n<\/ul>\n\n\n\n
          \u8fd9\u6bb5\u4ee3\u7801\u7b80\u6d01\u4f18\u96c5\u5730\u5b8c\u6210\u4e86\u201c\u65e0\u5e8f Map \u2192 \u6709\u5e8f Map\u201d\u7684\u8f6c\u6362\uff0c\u662f Stream \u5728\u65e5\u5e38\u4e1a\u52a1\u91cc\u975e\u5e38\u5e38\u89c1\u7684\u4e00\u79cd\u7528\u6cd5\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
          \u5728\u4e1a\u52a1\u5f00\u53d1\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u62ff\u5230\u8fd9\u6837\u4e00\u7c7b\u6570\u636e\uff1a \u8fd9\u662f\u4e00\u4e2a Map<String, BigDecimal&gt […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[56,37,1],"tags":[],"class_list":["post-1421","post","type-post","status-publish","format-standard","hentry","category-java","category-javaweblist","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/1421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1421"}],"version-history":[{"count":1,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/1421\/revisions"}],"predecessor-version":[{"id":1422,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/1421\/revisions\/1422"}],"wp:attachment":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1421"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1421"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}