{"id":89,"date":"2026-05-31T11:42:30","date_gmt":"2026-05-31T03:42:30","guid":{"rendered":"https:\/\/www.linerun.com.cn\/?p=89"},"modified":"2026-06-01T11:01:14","modified_gmt":"2026-06-01T03:01:14","slug":"%e4%b8%ba%e4%bb%80%e4%b9%88concurrenthashmap-%e4%b8%8d%e6%94%af%e6%8c%81-key-%e6%88%96-value-%e4%b8%ba-null","status":"publish","type":"post","link":"https:\/\/www.linerun.com.cn\/index.php\/2026\/05\/31\/%e4%b8%ba%e4%bb%80%e4%b9%88concurrenthashmap-%e4%b8%8d%e6%94%af%e6%8c%81-key-%e6%88%96-value-%e4%b8%ba-null\/","title":{"rendered":"005-\u4e3a\u4ec0\u4e48ConcurrentHashMap \u4e0d\u652f\u6301 key \u6216 value \u4e3a null?"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">\u6838\u5fc3\u539f\u56e0\u662f\u6d88\u9664\u6b67\u4e49\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ConcurrentHashMap\u662f\u4e3a\u5e76\u53d1\u73af\u5883\u8bbe\u8ba1\u7684\uff0c\u5982\u679c\u5141\u8bb8 value\u4e3anull,\u8c03\u7528 get(key)\u8fd4\u56denull\u65f6,\u4f60\u6ca1\u6cd5\u5224\u65ad\u662fkey\u4e0d\u5b58\u5728\u8fd8\u662f value \u672c\u8eab\u5c31\u662fnull\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5355\u7ebf\u7a0b\u4e0b\u8fd9\u4e2a\u95ee\u9898\u53ef\u4ee5\u7528containsKey \u6765\u533a\u5206\uff0c\u4f46\u5728\u5e76\u53d1\u73af\u5883\u4e0b\uff0c\u8fd9\u4e24\u6b65\u64cd\u4f5c\u4e4b\u95f4\u53ef\u80fd\u6709\u5176\u4ed6\u7ebf\u7a0b\u5728\u4fee\u6539map\uff0c\u5bfc\u81f4\u5224\u65ad\u5931\u6548\u3002DougLea\u8bbe\u8ba1\u65f6\u76f4\u63a5\u7981\u6b62null\uff0c\u4ece\u6839\u6e90\u4e0a\u907f\u514d\u4e86\u8fd9\u79cd\u6b67\u4e49\u3002\u5e76\u53d1\u573a\u666f\u4e0b\u7684\u6b67\u4e49\u95ee\u9898:<br>1.\u7ebf\u7a0bA\u8c03\u7528get(key)\u8fd4\u56denull<br>2.\u7ebf\u7a0bA\u8c03\u7528containsKey(key)\u60f3\u786e\u8ba4key\u662f\u5426\u5b58\u5728<br>3.\u5728\u8fd9\u4e24\u6b65\u4e4b\u95f4\uff0c\u7ebf\u7a0bB\u53ef\u80fd\u6267\u884c\u4e86 put(key, value)\u6216remove(key)<br>4.\u5bfc\u81f4\u7ebf\u7a0bA\u7684\u5224\u65ad\u7ed3\u679c\u4e0d\u53ef\u9760<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u53e6\u4e00\u4e2a\u539f\u56e0\u662f\u7b80\u5316\u5b9e\u73b0\u3002\u5982\u679c\u5141\u8bb8null\uff0cput\u3001get\u3001containsKey\u8fd9\u4e9b\u65b9\u6cd5\u90fd\u5f97\u52a0\u989d\u5916\u903b\u8f91\u53bb\u5904\u7406\u7a7a\u503c\u60c5\u51b5\uff0c\u4ee3\u7801\u590d\u6742\u5ea6\u4e0a\u5347\uff0c\u51fabug\u7684\u6982\u7387\u4e5f\u4f1a\u589e\u52a0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6838\u5fc3\u539f\u56e0\u662f\u6d88\u9664\u6b67\u4e49\u3002 ConcurrentHash &hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-89","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/89","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/comments?post=89"}],"version-history":[{"count":4,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/89\/revisions"}],"predecessor-version":[{"id":119,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/89\/revisions\/119"}],"wp:attachment":[{"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/media?parent=89"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/categories?post=89"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.linerun.com.cn\/index.php\/wp-json\/wp\/v2\/tags?post=89"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}