{"id":9782,"date":"2023-11-28T21:10:57","date_gmt":"2023-11-28T13:10:57","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=9782"},"modified":"2023-11-28T21:11:25","modified_gmt":"2023-11-28T13:11:25","slug":"java-zhonghashset-ru-he-jian-cha-zhong-fu-hashset","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/28\/java-zhonghashset-ru-he-jian-cha-zhong-fu-hashset\/","title":{"rendered":"Java\u4e2dHashSet\u5982\u4f55\u68c0\u67e5\u91cd\u590d? HashSet\u662f\u5982\u4f55\u4fdd\u8bc1\u6570\u636e\u4e0d\u53ef\u91cd\u590d\u7684\uff1f"},"content":{"rendered":"<p>1\u3001\u5411HashSet \u4e2dadd()\u5143\u7d20\u65f6\uff0c\u5224\u65ad\u5143\u7d20\u662f\u5426\u5b58\u5728\u7684\u4f9d\u636e\uff0c\u4e0d\u4ec5\u8981\u6bd4\u8f83 hash\u503c\uff0c\u540c\u65f6\u8fd8\u8981\u7ed3\u5408 equles() \u65b9\u6cd5\u6bd4\u8f83\u3002<br \/>\n2\u3001HashSet \u4e2d\u7684 add()\u65b9\u6cd5\u4f1a\u4f7f\u7528 HashMap \u7684 put()\u65b9\u6cd5\u3002<br \/>\n3\u3001HashMap \u7684 key \u662f\u552f\u4e00\u7684\uff0c\u7531\u6e90\u7801\u53ef\u4ee5\u770b\u51fa HashSet \u6dfb\u52a0\u8fdb\u53bb\u7684\u503c\u5c31\u662f\u4f5c\u4e3a HashMap \u7684 key\uff0c\u5e76\u4e14\u5728 HashMap \u4e2d\u5982\u679c K\/V\u76f8\u540c\u65f6\uff0c\u4f1a\u7528\u65b0\u7684V\u8986\u76d6\u6389\u65e7\u7684V\uff0c\u7136\u540e\u8fd4\u56de\u65e7\u7684V\u3002\u6240\u4ee5\u4e0d\u4f1a\u91cd\u590d\uff08 HashMap \u6bd4\u8f83 key \u662f\u5426\u76f8\u7b49\u662f\u5148\u6bd4\u8f83 hashcode \u518d\u6bd4\u8f83 equals()\uff09\u3002<br \/>\n\u4ee5\u4e0b\u662fHashSet \u90e8\u5206\u6e90\u7801\uff1a<br \/>\nprivate static final Object PRESENT = new Object();<br \/>\nprivate transient HashMap&lt;E, Object&gt; map;<br \/>\npublic HashSet(){<br \/>\nmap = new HashMap&lt;&gt;();<br \/>\n}<br \/>\npublic boolean add(E e\uff09{<br \/>\n\/\/\u8c03\u7528 HashMap \u7684 put \u65b9\u6cd5\uff0cPRESENT \u662f\u4e00\u4e2a\u81f3\u59cb\u81f3\u7ec8\u90fd\u76f8\u540c\u7684\u865a\u503c<br \/>\nreturn map.put(e, PRESENT)==null;<br \/>\n}<\/p>\n<p>hashCode()\u4e0eequals()\u7684\u76f8\u5173\u89c4\u5b9a\uff1a<br \/>\n1\u3001\u5982\u679c\u4e24\u4e2a\u5bf9\u8c61\u76f8\u7b49\uff0c\u5219hashcode\u4e00\u5b9a\u4e5f\u662f\u76f8\u540c\u7684\uff0chashCode \u662fjdk\u6839\u636e\u5bf9\u8c61\u7684\u5730\u5740\u6216\u8005\u5b57\u7b26\u4e32\u6216\u8005\u6570\u5b57\u7b97\u51fa\u6765\u7684 int \u7c7b\u578b\u7684\u6570\u503c<br \/>\n2\u3001\u4e24\u4e2a\u5bf9\u8c61\u76f8\u7b49\uff0c\u5bf9\u4e24\u4e2a\u5bf9\u8c61\u5206\u522b\u8c03\u7528 equals() \u65b9\u6cd5\u90fd\u8fd4\u56detrue<br \/>\n3\u3001\u4e24\u4e2a\u5bf9\u8c61\u6709\u76f8\u540c\u7684 hashcode \u503c\uff0c\u5b83\u4eec\u4e5f\u4e0d\u4e00\u5b9a\u662f\u76f8\u7b49\u7684<br \/>\n4\u3001\u7efc\u4e0a\uff0cequals() \u65b9\u6cd5\u88ab\u8986\u76d6\u8fc7\uff0c\u5219 hashCode() \u65b9\u6cd5\u4e5f\u5fc5\u987b\u88ab\u8986\u76d6<br \/>\n5\u3001hashCode()\u7684\u9ed8\u8ba4\u884c\u4e3a\u662f\u5bf9\u5806\u4e0a\u7684\u5bf9\u8c61\u4ea7\u751f\u72ec\u7279\u503c\u3002\u5982\u679c\u6ca1\u6709\u91cd\u5199hashCode()\uff0c\u5219\u8be5 class \u7684\u4e24\u4e2a\u5bf9\u8c61\u65e0\u8bba\u5982\u4f55\u90fd\u4e0d\u4f1a\u76f8\u7b49\uff08\u5373\u4f7f\u8fd9\u4e24\u4e2a\u5bf9\u8c61\u6307\u5411\u76f8\u540c\u7684\u6570\u636e\uff09\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>1\u3001\u5411HashSet \u4e2dadd()\u5143\u7d20\u65f6\uff0c\u5224\u65ad\u5143\u7d20\u662f\u5426\u5b58\u5728\u7684\u4f9d\u636e\uff0c\u4e0d\u4ec5\u8981\u6bd4\u8f83 hash\u503c\uff0c\u540c\u65f6\u8fd8\u8981\u7ed3\u5408 equ [&hellip;]<\/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-9782","post","type-post","status-publish","format-standard","hentry","category-javabase"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9782","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=9782"}],"version-history":[{"count":2,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9782\/revisions"}],"predecessor-version":[{"id":9794,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/9782\/revisions\/9794"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=9782"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=9782"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=9782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}