{"id":241,"date":"2024-11-23T09:29:28","date_gmt":"2024-11-23T01:29:28","guid":{"rendered":"https:\/\/obagg.com\/index.php\/2024\/11\/23\/hashmap%e5%ba%95%e5%b1%82%e5%ae%9e%e7%8e%b0%e5%8e%9f%e7%90%86\/"},"modified":"2024-11-23T09:29:28","modified_gmt":"2024-11-23T01:29:28","slug":"hashmap%e5%ba%95%e5%b1%82%e5%ae%9e%e7%8e%b0%e5%8e%9f%e7%90%86","status":"publish","type":"post","link":"https:\/\/obagg.com\/index.php\/2024\/11\/23\/hashmap%e5%ba%95%e5%b1%82%e5%ae%9e%e7%8e%b0%e5%8e%9f%e7%90%86\/","title":{"rendered":"HashMap\u5e95\u5c42\u5b9e\u73b0\u539f\u7406"},"content":{"rendered":"
    \n
  1. java1.7 \u4ee5\u524dHashMap\u5e95\u5c42\u7531\u6570\u7ec4+\u94fe\u8868\u5f62\u5f0f\u5b9e\u73b0\u3002
    \n1.1 \u63d2\u5165\u6570\u636e\u65f6\u9996\u5148\u8ba1\u7b97\u6570\u636ekey\u7684hash\u503c\uff0c\u6839\u636ehash\u627e\u5230\u5bf9\u5e94\u7684\u6570\u7ec4\u69fd\u4f4d\u3002
    \n1.2 \u627e\u5230\u69fd\u4f4d\u540e\uff0c\u5224\u65ad\u5f53\u524d\u6570\u7ec4\u69fd\u4f4d\u662f\u5426\u4e3anull\uff0cnull\u5219\u76f4\u63a5\u4f5c\u4e3a\u94fe\u8868\u8868\u5934\u63d2\u5165\uff0c\u5426\u5219\u5224\u65ad\u5f53\u524d\u9700\u8981\u63d2\u5165\u7684key\u662f\u5426\u5df2\u7ecf\u5728\u5f53\u524d\u69fd\u4f4d\u7684\u94fe\u8868\u4e2d\u5b58\u5728\uff0c\u5b58\u5728\u5219\u76f4\u63a5\u66ff\u6362\u65b0\u503c\uff0c\u4e0d\u5b58\u5728\u5219\u63d2\u5165\u5230\u5934\u7ed3\u70b9\u3002<\/li>\n<\/ol>\n
    \/\/ hash\u503c\u8ba1\u7b97\nstatic final int hash(Object key){\n  int h;\n  \/\/ h = key.hashCode() \u53d6hashCode\u503c\n  \/\/ h ^ (h >>> 16) \u9ad8\u4f4d\u8fd0\u7b97\n  return key == null ? 0 : (h = key.haskCode()) ^ (h >>> 16);\n}\n<\/code><\/pre>\n
      \/\/ \u8ba1\u7b97\u69fd\u4f4d\n  (n-1) & hash\n<\/code><\/pre>\n
      \n
    1. java1.8 \u5f15\u5165\u548c\u7ea2\u9ed1\u6811\uff0c\u5e95\u5c42\u7531\u6570\u7ec4+\u94fe\u8868+\u7ea2\u9ed1\u6811\u5b9e\u73b0\u3002
      \n2.1 java1.8\u4e2d\u63d2\u5165\u5143\u7d20\u65f6\uff0c\u4f1a\u5224\u65ad\u5f53\u524d\u69fd\u4f4d\u5bf9\u5e94\u7684\u94fe\u8868\u957f\u5ea6\uff0c\u5982\u679c\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e8\uff0c\u4f1a\u5c06\u94fe\u8868\u8f6c\u6362\u4e3a\u7ea2\u9ed1\u6811\u3002\u5f53\u7ea2\u9ed1\u6811\u8282\u70b9
      \n2.2 java1.8 \u5728\u94fe\u8868\u63d2\u5165\u5143\u7d20\u65f6\uff0c\u91c7\u7528\u7684\u5c3e\u90e8\u63d2\u5165\u6cd5\uff0c\u5373\u5c06\u65b0\u8282\u70b9\u63d2\u5165\u5230\u94fe\u8868\u5c3e\u90e8\u3002
      \n2.3 \u4e3a\u4ec0\u4e48\u5f15\u5165\u7ea2\u9ed1\u6811\uff1ajdk1.8\u4ee5\u524d\u7531\u4e8e\u94fe\u8868\u7684\u67e5\u8be2\u6548\u7387\u975e\u5e38\u4f4e\uff0c\u5f53hash\u51b2\u7a81\u4e25\u91cd\u65f6\uff0c\u94fe\u8868\u8fc7\u957f\uff0c\u4e25\u91cd\u5f71\u54cd\u67e5\u8be2\u6027\u80fd\u3002\u6563\u5217\u5217\u8868\u6700\u7406\u60f3\u7684\u67e5\u8be2\u6548\u7387\u4e3aO(1)\uff0c\u4f46\u662f\u94fe\u8868\u8fc7\u957f\u65f6\uff0c\u4f1a\u5bfc\u81f4\u67e5\u8be2\u9000\u5316\u4e3aO(n)\u3002\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\u6240\u4ee5jdk8\u4e2d\u7684HashMap\u6dfb\u52a0\u4e86\u7ea2\u9ed1\u6811\u6765\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5f53\u94fe\u8868\u957f\u5ea6>=8\u7684\u65f6\u5019\u94fe\u8868\u5c31\u4f1a\u53d8\u6210\u7ea2\u9ed1\u6811\uff0c\u7ea2\u9ed1\u6811\u5176\u5b9e\u5c31\u662f\u4e00\u9897\u7279\u6b8a\u7684\u4e8c\u53c9\u6392\u5e8f\u6811\uff0c\u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6\u4e3aO(log2(n))\u3002<\/li>\n<\/ol>\n
      Please credit: OBA Blog<\/a> » HashMap\u5e95\u5c42\u5b9e\u73b0\u539f\u7406<\/a><\/p>","protected":false},"excerpt":{"rendered":"
      java1.7 \u4ee5\u524dHashMap\u5e95\u5c42\u7531\u6570\u7ec4+\u94fe\u8868\u5f62\u5f0f\u5b9e\u73b0\u3002 1.1 \u63d2\u5165\u6570\u636e\u65f6\u9996\u5148\u8ba1\u7b97\u6570\u636ekey\u7684hash\u503c\uff0c\u6839\u636ehash\u627e\u5230\u5bf9\u5e94\u7684\u6570\u7ec4\u69fd\u4f4d\u3002 1.2 \u627e\u5230\u69fd\u4f4d\u540e\uff0c\u5224\u65ad\u5f53\u524d\u6570\u7ec4\u69fd\u4f4d\u662f\u5426\u4e3anull\uff0cnull\u5219\u76f4\u63a5\u4f5c\u4e3a\u94fe\u8868\u8868\u5934\u63d2\u5165\uff0c\u5426\u5219\u5224\u65ad\u5f53\u524d\u9700\u8981\u63d2\u5165\u7684key\u662f\u5426\u5df2\u7ecf\u5728\u5f53\u524d\u69fd\u4f4d\u7684\u94fe\u8868\u4e2d\u5b58\u5728\uff0c\u5b58\u5728\u5219\u76f4\u63a5\u66ff\u6362\u65b0\u503c\uff0c\u4e0d\u5b58\u5728\u5219\u63d2\u5165\u5230\u5934\u7ed3\u70b9\u3002 \/\/ hash\u503c\u8ba1\u7b97 static final int hash(Object key){ int h; \/\/ h = key.hashCode() \u53d6hashCode\u503c \/\/ h ^ (h >>> 16) \u9ad8\u4f4d\u8fd0\u7b97 return key == null ? 0 : (h = key.haskCode()) ^ (h >>> 16); } \/\/ \u8ba1\u7b97\u69fd\u4f4d (n-1) & hash java1.8 \u5f15\u5165\u548c\u7ea2\u9ed1\u6811\uff0c\u5e95\u5c42\u7531\u6570\u7ec4+\u94fe\u8868+\u7ea2\u9ed1\u6811\u5b9e\u73b0\u3002 2.1 java1.8\u4e2d\u63d2\u5165\u5143\u7d20\u65f6\uff0c\u4f1a\u5224\u65ad\u5f53\u524d\u69fd\u4f4d\u5bf9\u5e94\u7684\u94fe\u8868\u957f\u5ea6\uff0c\u5982\u679c\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e8\uff0c\u4f1a\u5c06\u94fe\u8868\u8f6c\u6362\u4e3a\u7ea2\u9ed1\u6811\u3002\u5f53\u7ea2\u9ed1\u6811\u8282\u70b9 2.2 java1.8 \u5728\u94fe\u8868\u63d2\u5165\u5143\u7d20\u65f6\uff0c\u91c7\u7528\u7684\u5c3e\u90e8\u63d2\u5165\u6cd5\uff0c\u5373\u5c06\u65b0\u8282\u70b9\u63d2\u5165\u5230\u94fe\u8868\u5c3e\u90e8\u3002 2.3 \u4e3a\u4ec0\u4e48\u5f15\u5165\u7ea2\u9ed1\u6811\uff1ajdk1.8\u4ee5\u524d\u7531\u4e8e\u94fe\u8868\u7684\u67e5\u8be2\u6548\u7387\u975e\u5e38\u4f4e\uff0c\u5f53hash\u51b2\u7a81\u4e25\u91cd\u65f6\uff0c\u94fe\u8868\u8fc7\u957f\uff0c\u4e25\u91cd\u5f71\u54cd\u67e5\u8be2\u6027\u80fd\u3002\u6563\u5217\u5217\u8868\u6700\u7406\u60f3\u7684\u67e5\u8be2\u6548\u7387\u4e3aO(1)\uff0c\u4f46\u662f\u94fe\u8868\u8fc7\u957f\u65f6\uff0c\u4f1a\u5bfc\u81f4\u67e5\u8be2\u9000\u5316\u4e3aO(n)\u3002\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\u6240\u4ee5jdk8\u4e2d\u7684HashMap\u6dfb\u52a0\u4e86\u7ea2\u9ed1\u6811\u6765\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5f53\u94fe\u8868\u957f\u5ea6>=8\u7684\u65f6\u5019\u94fe\u8868\u5c31\u4f1a\u53d8\u6210\u7ea2\u9ed1\u6811\uff0c\u7ea2\u9ed1\u6811\u5176\u5b9e\u5c31\u662f\u4e00\u9897\u7279\u6b8a\u7684\u4e8c\u53c9\u6392\u5e8f\u6811\uff0c\u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6\u4e3aO(log2(n))\u3002 Please credit: OBA Blog » HashMap\u5e95\u5c42\u5b9e\u73b0\u539f\u7406<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-241","post","type-post","status-publish","format-standard","hentry","category-share"],"_links":{"self":[{"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/posts\/241","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/comments?post=241"}],"version-history":[{"count":0,"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/posts\/241\/revisions"}],"wp:attachment":[{"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/media?parent=241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/categories?post=241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/obagg.com\/index.php\/wp-json\/wp\/v2\/tags?post=241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}