{"id":3965,"date":"2025-07-20T11:30:17","date_gmt":"2025-07-20T03:30:17","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=3965"},"modified":"2025-07-20T11:30:17","modified_gmt":"2025-07-20T03:30:17","slug":"concurrenthashmap%e7%9a%84size%e6%96%b9%e6%b3%95%e6%98%af%e7%ba%bf%e7%a8%8b%e5%ae%89%e5%85%a8%e7%9a%84%e5%90%97%ef%bc%9f%e4%b8%ba%e4%bb%80%e4%b9%88","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/07\/20\/concurrenthashmap%e7%9a%84size%e6%96%b9%e6%b3%95%e6%98%af%e7%ba%bf%e7%a8%8b%e5%ae%89%e5%85%a8%e7%9a%84%e5%90%97%ef%bc%9f%e4%b8%ba%e4%bb%80%e4%b9%88\/","title":{"rendered":"ConcurrentHashMap\u7684size()\u65b9\u6cd5\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\u5417\uff1f\u4e3a\u4ec0\u4e48"},"content":{"rendered":"\n<p><code>ConcurrentHashMap<\/code> \u7684 <code>size()<\/code> \u65b9\u6cd5 <strong>\u662f\u7ebf\u7a0b\u5b89\u5168\u7684<\/strong>\uff0c\u4f46\u5b83\u7684\u51c6\u786e\u6027\u548c\u6027\u80fd\u8868\u73b0\u4e0e\u666e\u901a <code>HashMap<\/code> \u4e0d\u540c\uff0c\u5177\u4f53\u539f\u56e0\u548c\u5b9e\u73b0\u7ec6\u8282\u5982\u4e0b\uff1a<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e00\u3001\u7ebf\u7a0b\u5b89\u5168\u6027<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>ConcurrentHashMap<\/code> \u8bbe\u8ba1\u7528\u4e8e\u9ad8\u5e76\u53d1\u73af\u5883\uff0c\u5185\u90e8\u901a\u8fc7\u5206\u6bb5\uff08Java 8 \u4e4b\u540e\u91c7\u7528\u8282\u70b9\u6570\u7ec4 + CAS + synchronized\uff09\u673a\u5236\u4fdd\u8bc1\u5e76\u53d1\u8bfb\u5199\u5b89\u5168\u3002<\/li>\n\n\n\n<li><code>size()<\/code> \u65b9\u6cd5\u5728\u5e76\u53d1\u73af\u5883\u4e2d\u8c03\u7528\uff0c\u4e0d\u4f1a\u629b\u51fa\u5f02\u5e38\uff0c\u4e5f\u4e0d\u4f1a\u8fd4\u56de\u90e8\u5206\u635f\u574f\u7684\u6570\u636e\u7ed3\u6784\uff0c\u7ebf\u7a0b\u5b89\u5168\u5730\u8fd4\u56de\u5f53\u524d\u5143\u7d20\u4e2a\u6570\u7684\u4f30\u8ba1\u503c\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e8c\u3001\u4e3a\u4ec0\u4e48\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff1f<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7ebf\u7a0b\u5b89\u5168\u4f53\u73b0\u5728\u8c03\u7528 <code>size()<\/code> \u4e0d\u4f1a\u5bfc\u81f4\u5185\u90e8\u6570\u636e\u7ed3\u6784\u5f02\u5e38\uff0c\u4e5f\u4e0d\u4f1a\u629b\u51fa <code>ConcurrentModificationException<\/code>\u3002<\/li>\n\n\n\n<li><code>ConcurrentHashMap<\/code> \u7684 <code>size()<\/code> \u5e76\u4e0d\u662f\u7b80\u5355\u5730\u8fd4\u56de\u4e00\u4e2a\u8ba1\u6570\u5668\uff0c\u800c\u662f\u52a8\u6001\u8ba1\u7b97\u5404\u4e2a\u6bb5\uff08\u6876\uff09\u4e2d\u5143\u7d20\u4e2a\u6570\u7684\u548c\uff0c\u8fc7\u7a0b\u4e2d\u5141\u8bb8\u6709\u5e76\u53d1\u66f4\u65b0\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e09\u3001\u51c6\u786e\u6027\u95ee\u9898<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>size()<\/code> \u8fd4\u56de\u7684\u503c\u662f <strong>\u8fd1\u4f3c\u503c<\/strong>\uff0c\u5728\u5e76\u53d1\u5199\u64cd\u4f5c\u6fc0\u70c8\u65f6\uff0c\u53ef\u80fd\u4e0e\u5b9e\u9645\u5143\u7d20\u6570\u91cf\u6709\u504f\u5dee\u3002<\/li>\n\n\n\n<li>\u8fd9\u662f\u56e0\u4e3a\u5e76\u53d1\u73af\u5883\u4e2d\u591a\u4e2a\u7ebf\u7a0b\u5728\u5bf9\u6876\u7684\u5143\u7d20\u8fdb\u884c\u63d2\u5165\u548c\u5220\u9664\uff0c<code>size()<\/code> \u5e76\u4e0d\u52a0\u9501\u963b\u585e\u6574\u4e2a\u7ed3\u6784\u4ee5\u83b7\u5f97\u5b8c\u5168\u51c6\u786e\u7684\u503c\uff0c\u8fd9\u6837\u505a\u53ef\u4ee5\u5927\u5e45\u63d0\u5347\u6027\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u56db\u3001\u6e90\u7801\u5173\u952e\u70b9\uff08Java 8 \u53ca\u4ee5\u540e\uff09<\/h2>\n\n\n\n<p><code>ConcurrentHashMap<\/code> \u4e2d <code>size()<\/code> \u8c03\u7528\u5185\u90e8\u7684 <code>sumCount()<\/code>\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public int size() {\n    long n = sumCount();\n    return ((n &lt; 0L) ? 0 : ((n &gt; (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int)n));\n}<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>sumCount()<\/code> \u65b9\u6cd5\u4f1a\u904d\u5386\u6240\u6709 <code>CounterCell<\/code> \u548c baseCount \u7d2f\u52a0\u603b\u548c\u3002<\/li>\n\n\n\n<li><code>CounterCell<\/code> \u662f\u4e00\u79cd\u5206\u6563\u7684\u8ba1\u6570\u5668\uff0c\u907f\u514d\u591a\u4e2a\u7ebf\u7a0b\u4e89\u62a2\u540c\u4e00\u4e2a\u8ba1\u6570\u53d8\u91cf\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e94\u3001\u5982\u679c\u9700\u8981\u5b8c\u5168\u51c6\u786e\u7684\u5927\u5c0f\uff0c\u600e\u4e48\u529e\uff1f<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7531\u4e8e <code>ConcurrentHashMap<\/code> \u8bbe\u8ba1\u76ee\u6807\u662f\u6027\u80fd\uff0c\u5b8c\u5168\u51c6\u786e\u7684\u5927\u5c0f\u5728\u9ad8\u5e76\u53d1\u4e0b\u5f00\u9500\u5f88\u5927\u3002<\/li>\n\n\n\n<li>\u53ef\u4ee5\u901a\u8fc7\u989d\u5916\u540c\u6b65\u548c\u5feb\u7167\u6280\u672f\u5b9e\u73b0\u51c6\u786e\u8ba1\u6570\uff0c\u4f46\u4ee3\u4ef7\u8f83\u9ad8\u3002<\/li>\n\n\n\n<li>\u5982\u679c\u786e\u5b9e\u9700\u8981\u7cbe\u786e\u8ba1\u6570\uff0c\u4e14\u5199\u64cd\u4f5c\u4e0d\u9891\u7e41\uff0c\u53ef\u4ee5\u5c06\u64cd\u4f5c\u653e\u5165\u5916\u5c42\u52a0\u9501\u4ee3\u7801\u5757\u4e2d\u3002<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u516d\u3001\u603b\u7ed3<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u70b9<\/th><th>\u8bf4\u660e<\/th><\/tr><\/thead><tbody><tr><td><code>size()<\/code> \u7ebf\u7a0b\u5b89\u5168<\/td><td>\u662f\uff0c\u8c03\u7528\u4e0d\u4f1a\u629b\u5f02\u5e38\uff0c\u5185\u90e8\u8ba1\u6570\u5b89\u5168<\/td><\/tr><tr><td><code>size()<\/code> \u51c6\u786e\u5ea6<\/td><td>\u8fd1\u4f3c\u503c\uff0c\u53ef\u80fd\u5b58\u5728\u8f7b\u5fae\u8bef\u5dee<\/td><\/tr><tr><td>\u6027\u80fd<\/td><td>\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e2d\u6027\u80fd\u4f18\u4e8e\u52a0\u9501\u83b7\u53d6\u51c6\u786e\u8ba1\u6570\u65b9\u6848<\/td><\/tr><tr><td>\u9002\u7528\u573a\u666f<\/td><td>\u9002\u5408\u5bf9\u5927\u5c0f\u6709\u8fd1\u4f3c\u9700\u6c42\u7684\u7edf\u8ba1\u6216\u76d1\u63a7<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e03\u3001\u53c2\u8003\u8d44\u6599<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/github.com\/openjdk\/jdk\/blob\/master\/src\/java.base\/share\/classes\/java\/util\/concurrent\/ConcurrentHashMap.java#L1430\">OpenJDK ConcurrentHashMap \u6e90\u7801<\/a><\/li>\n\n\n\n<li>\u300aJava\u5e76\u53d1\u7f16\u7a0b\u5b9e\u6218\u300b\u2014\u2014 ConcurrentHashMap\u7ae0\u8282<\/li>\n\n\n\n<li><a href=\"https:\/\/docs.oracle.com\/javase\/8\/docs\/api\/java\/util\/concurrent\/ConcurrentHashMap.html#size--\">Oracle\u5b98\u65b9\u6587\u6863 ConcurrentHashMap<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/segmentfault.com\/a\/1190000022543487\">\u6df1\u5165\u7406\u89e3Java\u4e2d\u7684ConcurrentHashMap<\/a><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>ConcurrentHashMap \u7684 size() \u65b9\u6cd5 \u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u4f46\u5b83\u7684\u51c6\u786e\u6027\u548c\u6027\u80fd\u8868\u73b0\u4e0e\u666e\u901a Has [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3966,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[68,86],"tags":[],"class_list":["post-3965","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","category-java-"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3965","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=3965"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3965\/revisions"}],"predecessor-version":[{"id":3967,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3965\/revisions\/3967"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media\/3966"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=3965"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=3965"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=3965"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}