{"id":202886,"date":"2025-05-22T09:27:14","date_gmt":"2025-05-22T01:27:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/202886\/"},"modified":"2025-05-22T09:27:14","modified_gmt":"2025-05-22T01:27:14","slug":"java%e5%87%bd%e6%95%b0%e7%9a%84%e5%8f%82%e6%95%b0%e6%98%af%e5%90%a6%e5%8f%af%e4%bb%a5%e6%9c%89%e6%b3%9b%e5%9e%8b%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/202886\/","title":{"rendered":"Java\u51fd\u6570\u7684\u53c2\u6570\u662f\u5426\u53ef\u4ee5\u6709\u6cdb\u578b\uff1f"},"content":{"rendered":"

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

Java\u51fd\u6570\u7684\u53c2\u6570\u662f\u5426\u53ef\u4ee5\u6709\u6cdb\u578b\uff1f<\/h1>\n

\u4e00\u5206\u8015\u8018\uff0c\u4e00\u5206\u6536\u83b7\uff01\u65e2\u7136\u6253\u5f00\u4e86\u8fd9\u7bc7\u6587\u7ae0\u300aJava\u51fd\u6570\u7684\u53c2\u6570\u662f\u5426\u53ef\u4ee5\u6709\u6cdb\u578b\uff1f\u300b<\/span>\uff0c\u5c31\u575a\u6301\u770b\u4e0b\u53bb\u5427\uff01\u6587\u4e2d\u5185\u5bb9\u5305\u542b<\/span>\u7b49\u7b49\u77e5\u8bc6\u70b9…\u5e0c\u671b\u4f60\u80fd\u5728\u9605\u8bfb\u672c\u6587\u540e\uff0c\u80fd\u771f\u771f\u5b9e\u5b9e\u5b66\u5230\u77e5\u8bc6\u6216\u8005\u5e2e\u4f60\u89e3\u51b3\u5fc3\u4e2d\u7684\u7591\u60d1\uff0c\u4e5f\u6b22\u8fce\u5927\u4f6c\u6216\u8005\u65b0\u4eba\u670b\u53cb\u4eec\u591a\u7559\u8a00\u8bc4\u8bba\uff0c\u591a\u7ed9\u5efa\u8bae\uff01\u8c22\u8c22\uff01<\/p>\n

<\/p>\n

Java \u51fd\u6570\u4e2d\u6cdb\u578b\u53c2\u6570\u7684\u4f7f\u7528<\/strong><\/p>\n

Java \u5141\u8bb8\u5728\u51fd\u6570\u7684\u53c2\u6570\u4e0a\u4f7f\u7528\u6cdb\u578b\uff0c\u4f7f\u51fd\u6570\u66f4\u52a0\u7075\u6d3b\u548c\u53ef\u91cd\u7528\u3002\u6cdb\u578b\u53c2\u6570\u4f5c\u4e3a\u5360\u4f4d\u7b26\uff0c\u53ef\u4ee5\u5728\u51fd\u6570\u8c03\u7528\u65f6\u4f20\u5165\u4e0d\u540c\u7684\u7c7b\u578b\u53c2\u6570\u3002<\/p>\n

\u8bed\u6cd5<\/strong><\/p>\n

\u6cdb\u578b\u53c2\u6570\u5728\u51fd\u6570\u7b7e\u540d\u4e2d\u4f7f\u7528\u5c16\u62ec\u53f7 <> \u62ec\u8d77\u6765\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n

public <T> void func(T param) {\n    \/\/ ...\n}<\/pre>\n
\u5b9e\u6218\u6848\u4f8b<\/strong><\/p>\n
\u5047\u8bbe\u6211\u4eec\u8981\u7f16\u5199\u4e00\u4e2a\u51fd\u6570\uff0c\u5bf9\u7ed9\u5b9a\u5217\u8868\u4e2d\u7684\u5143\u7d20\u8fdb\u884c\u6c42\u548c\u3002\u4f7f\u7528\u6cdb\u578b\uff0c\u6211\u4eec\u53ef\u4ee5\u8ba9\u51fd\u6570\u9002\u7528\u4e8e\u5404\u79cd\u5143\u7d20\u7c7b\u578b\uff1a<\/p>\n
public static <T extends Number> double sum(List<T> numbers) {\n    double sum = 0.0;\n    for (T number : numbers) {\n        sum += number.doubleValue();\n    }\n    return sum;\n}<\/pre>\n
\u6cdb\u578b\u53c2\u6570\u9650\u5236<\/strong><\/p>\n
\u6cdb\u578b\u53c2\u6570\u53ef\u4ee5\u53d7\u5230\u9650\u5236\uff0c\u4ee5\u786e\u4fdd\u4f20\u5165\u7684\u7c7b\u578b\u6ee1\u8db3\u67d0\u4e9b\u6761\u4ef6\u3002\u9650\u5236\u4f7f\u7528\u901a\u914d\u7b26\uff08\u4f8b\u5982 ? extends T<\/code>\uff09\u6216\u63a5\u53e3\u8fb9\u754c\uff08\u4f8b\u5982 ? extends Number<\/code>\uff09\uff1a<\/p>\n
    \n
  • ? extends T<\/code>\uff1a<\/strong>\u5c06\u7c7b\u578b\u9650\u5236\u4e3a T \u6216\u5176\u5b50\u7c7b\uff08\u534f\u53d8\uff09\u3002<\/li>\n
  • ? super T<\/code>\uff1a<\/strong>\u5c06\u7c7b\u578b\u9650\u5236\u4e3a T \u6216\u5176\u8d85\u7c7b\uff08\u9006\u53d8\uff09\u3002<\/li>\n
  • ? extends Number<\/code>\uff1a<\/strong>\u5c06\u7c7b\u578b\u9650\u5236\u4e3a Number \u6216\u5176\u5b50\u7c7b\u3002<\/li>\n<\/ul>\n
    \u4f7f\u7528\u901a\u914d\u7b26<\/strong><\/p>\n
    \u4f7f\u7528\u901a\u914d\u7b26\u53ef\u4ee5\u7f16\u5199\u66f4\u901a\u7528\u7684\u51fd\u6570\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u4ee5\u7f16\u5199\u4e00\u4e2a\u901a\u7528\u51fd\u6570\uff0c\u5c06\u4efb\u4f55\u7c7b\u578b\u7684\u5217\u8868\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff1a<\/p>\n
    public static <T> String toString(List<T> list) {\n    StringBuilder sb = new StringBuilder();\n    for (T item : list) {\n        sb.append(item.toString());\n    }\n    return sb.toString();\n}<\/pre>\n
    \u4f18\u52bf<\/strong><\/p>\n
    \u4f7f\u7528\u6cdb\u578b\u53c2\u6570\u6709\u4ee5\u4e0b\u4f18\u52bf\uff1a<\/p>\n
      \n
    • \u4ee3\u7801\u53ef\u91cd\u7528\uff1a<\/strong>\u6cdb\u578b\u51fd\u6570\u53ef\u4ee5\u9002\u7528\u4e8e\u5404\u79cd\u7c7b\u578b\uff0c\u65e0\u9700\u91cd\u5199\u591a\u4e2a\u7279\u5b9a\u7c7b\u578b\u7684\u51fd\u6570\u3002<\/li>\n
    • \u7c7b\u578b\u5b89\u5168\uff1a<\/strong>\u7f16\u8bd1\u5668\u4f1a\u5f3a\u5236\u6267\u884c\u6cdb\u578b\u53c2\u6570\u9650\u5236\uff0c\u786e\u4fdd\u7c7b\u578b\u5339\u914d\u6b63\u786e\u3002<\/li>\n
    • \u7075\u6d3b\u6027\uff1a<\/strong>\u6cdb\u578b\u5141\u8bb8\u51fd\u6570\u4ee5\u4e0d\u540c\u7684\u65b9\u5f0f\u5904\u7406\u4e0d\u540c\u7c7b\u578b\u7684\u5143\u7d20\u3002<\/li>\n<\/ul>\n
      \u4ee5\u4e0a\u5c31\u662f\u672c\u6587\u7684\u5168\u90e8\u5185\u5bb9\u4e86\uff0c\u662f\u5426\u6709\u987a\u5229\u5e2e\u52a9\u4f60\u89e3\u51b3\u95ee\u9898\uff1f\u82e5\u662f\u80fd\u7ed9\u4f60\u5e26\u6765\u5b66\u4e60\u4e0a\u7684\u5e2e\u52a9\uff0c\u8bf7\u5927\u5bb6\u591a\u591a\u652f\u6301\uff01\u66f4\u591a\u5173\u4e8e\u6587\u7ae0\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u4e5f\u53ef\u5173\u6ce8\u516c\u4f17\u53f7\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
      Java\u51fd\u6570\u7684\u53c2\u6570\u662f\u5426\u53ef\u4ee5\u6709\u6cdb\u578b...<\/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-202886","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202886","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=202886"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/202886\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=202886"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=202886"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=202886"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}