Java \u4e2dHashMap \u4e0e HashTable \u6709\u4ec0\u4e48\u533a\u522b?
\n1\u3001\u7ebf\u7a0b\u5b89\u5168\uff1a HashMap \u662f\u975e\u7ebf\u7a0b\u5b89\u5168\u7684\uff0cHashTable \u662f\u7ebf\u7a0b\u5b89\u5168\u7684;
\nHashTable\u5185\u90e8\u7684\u65b9\u6cd5\u57fa\u672c\u90fd\u7ecf\u8fc7synchronized\u4fee\u9970\u3002\uff08\u5982\u679c\u4f60\u8981\u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168\u7684\u8bdd\u5c31\u4f7f\u7528ConcurrentHashMap\uff09\uff1b
\n2\u3001\u6548\u7387\uff1a\u56e0\u4e3a\u7ebf\u7a0b\u5b89\u5168\u7684\u95ee\u9898\uff0cHashMap \u8981\u6bd4 HashTable \u6548\u7387\u9ad8\u4e00\u70b9\u3002\u53e6\u5916\uff0cHashTable \u57fa\u672c\u88ab\u6dd8\u6c70\uff0c\u4e0d\u8981\u5728\u4ee3\u7801\u4e2d\u4f7f\u7528\u5b83\uff1b\uff08\u5982\u679c\u4f60\u8981\u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168\u7684\u8bdd\u5c31\u4f7f\u7528 ConcurrentHashMap\uff09\uff1b
\n3\u3001\u5bf9Nul key \u548cNull value \u7684\u652f\u6301\uff1a HashMap \u4e2d\uff0cnull \u53ef\u4ee5\u4f5c\u4e3a\u952e\uff0c\u8fd9\u6837\u7684\u952e\u53ea\u6709\u4e00\u4e2a\uff0c\u53ef\u4ee5\u6709\u4e00\u4e2a\u6216\u591a\u4e2a\u952e\u6240\u5bf9\u5e94\u7684\u503c\u4e3a null\u3002\u4f46\u662f\u5728HashTable \u4e2d put \u8fdb\u7684\u952e\u503c\u53ea\u8981\u6709\u4e00\u4e2a null\uff0c\u76f4\u63a5\u629b NullPointerException.
\n4\u3001\u521d\u59cb\u5bb9\u91cf\u5927\u5c0f\u548c\u6bcf\u6b21\u6269\u5145\u5bb9\u91cf\u5927\u5c0f\u7684\u4e0d\u540c\uff1a
\n(1)\u3001\u521b\u5efa\u65f6\u5982\u679c\u4e0d\u6307\u5b9a\u5bb9\u91cf\u521d\u59cb\u503c\uff0cHashtable \u9ed8\u8ba4\u7684\u521d\u59cb\u5927\u5c0f\u4e3a 11\uff0c\u4e4b\u540e\u6bcf\u6b21\u6269\u5145\uff0c\u5bb9\u91cf\u53d8\u4e3a\u539f\u6765\u76842n+1\u3002HashMap \u9ed8\u8ba4\u7684\u521d\u59cb\u5316\u5927\u5c0f\u4e3a 16\u3002\u4e4b\u540e\u6bcf\u6b21\u6269\u5145\uff0c\u5bb9\u91cf\u53d8\u4e3a\u539f\u6765\u7684 2 \u500d\u3002
\n(2)\u3001\u521b\u5efa\u65f6\u5982\u679c\u7ed9\u5b9a\u4e86\u5bb9\u91cf\u521d\u59cb\u503c\uff0c\u90a3\u4e48 Hashtable \u4f1a\u76f4\u63a5\u4f7f\u7528\u4f60\u7ed9\u5b9a\u7684\u5927\u5c0f\uff0c\u800c HashMap \u4f1a\u5c06\u5176\u6269\u5145\u4e3a 2 \u7684\u5e42\u6b21\u65b9\u5927\u5c0f\u3002\u4e5f\u5c31\u662f\u8bf4 HashMap \u603b\u662f\u4f7f\u75282 \u7684\u5e42\u4f5c\u4e3a\u54c8\u5e0c\u8868\u7684\u5927\u5c0f\uff0c\u540e\u9762\u4f1a\u4ecb\u7ecd\u5230\u4e3a\u4ec0\u4e48\u662f2\u7684\u5e42\u6b21\u65b9\u3002<\/p>\n
\u5e95\u5c42\u6570\u636e\u7ed3\u6784\uff1a
\nJDK1.8 \u4ee5\u540e\u7684 HashMap \u5728\u89e3\u51b3\u54c8\u5e0c\u51b2\u7a81\u65f6\u6709\u4e86\u8f83\u5927\u7684\u53d8\u5316\uff0c\u5f53\u94fe\u8868\u957f\u5ea6\u5927\u4e8e\u9608\u503c\uff08\u9ed8\u8ba4\u4e3a 8\uff09\u65f6\uff0c\u5c06\u94fe\u8868\u8f6c\u5316\u4e3a\u7ea2\u9ed1\u6811\uff0c\u4ee5\u51cf\u5c11\u641c\u7d22\u65f6\u95f4\u3002Hashtable \u6ca1\u6709\u8fd9\u6837\u7684\u673a\u5236\u3002
\n\u63a8\u8350\u4f7f\u7528\uff1a
\n\u5728 Hashtable \u7684\u7c7b\u6ce8\u91ca\u53ef\u4ee5\u770b\u5230\uff0cHashtable \u662f\u4fdd\u7559\u7c7b\u4e0d\u5efa\u8bae\u4f7f\u7528\uff0c\u63a8\u8350\u5728\u5355\u7ebf\u7a0b\u73af\u5883\u4e0b\u4f7f\u7528 HashMap \u66ff\u4ee3\uff0c\u5982\u679c\u9700\u8981\u591a\u7ebf\u7a0b\u4f7f\u7528\u5219\u7528ConcurrentHashMap \u66ff\u4ee3\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
Java \u4e2dHashMap \u4e0e HashTable \u6709\u4ec0\u4e48\u533a\u522b? 1\u3001\u7ebf\u7a0b\u5b89\u5168\uff1a HashMap \u662f\u975e\u7ebf\u7a0b\u5b89\u5168 […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[99],"tags":[],"class_list":["post-9262","post","type-post","status-publish","format-standard","hentry","category-javabase"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9262","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=9262"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9262\/revisions"}],"predecessor-version":[{"id":9263,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9262\/revisions\/9263"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=9262"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=9262"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=9262"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}