{"id":123299,"date":"2026-11-07T01:16:59","date_gmt":"2026-11-06T17:16:59","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/123299.html"},"modified":"2026-11-07T01:16:59","modified_gmt":"2026-11-06T17:16:59","slug":"%e9%83%bd-2026-%e5%b9%b4%e4%ba%86%ef%bc%8c%e4%bd%a0%e7%9c%9f%e7%9a%84%e6%90%9e%e6%b8%85%e6%a5%9a-hashmap-%e5%9c%a8-jdk-1-7-%e5%92%8c-1-8-%e4%b9%8b%e9%97%b4%e5%88%b0%e5%ba%95%e5%8f%98%e4%ba%86%e4%bb%80","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/123299.html","title":{"rendered":"\u90fd 2026 \u5e74\u4e86\uff0c\u4f60\u771f\u7684\u641e\u6e05\u695a HashMap \u5728 JDK 1.7 \u548c 1.8 \u4e4b\u95f4\u5230\u5e95\u53d8\u4e86\u4ec0\u4e48\u5417\uff1f"},"content":{"rendered":"<p> <img decoding=\"async\" width=\"1000\" src=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/11\/20261106171658-6aee0b8a61316.png\" \/> <\/p>\n<p>\u3297\ufe0f\u672c\u671f\u5185\u5bb9\u5df2\u6536\u5f55\u81f3\u4e13\u680f\u300aJava\u6838\u5fc3\u5b9e\u64cd(\u8fdb\u9636\u7248)\u300b&#xff0c;\u6301\u7eed\u5b8c\u5584\u77e5\u8bc6\u4f53\u7cfb\u4e0e\u9879\u76ee\u5b9e\u6218&#xff0c;\u5efa\u8bae\u5148\u8ba2\u9605\u6536\u85cf&#xff0c;\u540e\u7eed\u67e5\u9605\u66f4\u65b9\u4fbf&#xff5e; \u3299\ufe0f\u672c\u671f\u96be\u5ea6\u6307\u6570&#xff1a;\u2b50\u2b50\u2b50 &#x1f250;\u798f\u5229&#xff1a; <font color=\"red\">\u4e00\u6b21\u8ba2\u9605\u540e&#xff0c;\u4e13\u680f\u5185\u7684\u6240\u6709\u6587\u7ae0\u53ef\u6c38\u4e45\u514d\u8d39\u770b&#xff0c;\u6301\u7eed\u66f4\u65b0\u4e2d&#xff0c;\u4fdd\u5e951000&#043;(\u7bc7)\u786c\u6838\u5b9e\u6218\u5185\u5bb9\u3002<\/font><\/p>\n<h3>\u524d\u8a00&#xff1a;\u4ece\u4e00\u6b21\u7ebf\u4e0a\u4e8b\u6545\u8bf4\u8d77<\/h3>\n<p>\u90a3\u662f\u67d0\u5e74\u67d0\u6708&#xff0c;\u4e00\u4e2a\u51cc\u6668\u4e09\u70b9\u7684\u751f\u4ea7\u73af\u5883\u3002<\/p>\n<p>\u6211\u76ef\u7740\u76d1\u63a7\u5927\u5c4f&#xff0c;CPU \u98d9\u5230 100%&#xff0c;\u67d0\u4e2a\u670d\u52a1\u7ebf\u7a0b\u5168\u5361\u6b7b&#xff0c;\u65e5\u5fd7\u91cc\u4e00\u5806 java.lang.OutOfMemoryError&#xff0c;\u770b\u5f97\u6211\u5934\u76ae\u53d1\u9ebb\u3002\u6392\u67e5\u5230\u6700\u540e&#xff0c;\u5b9a\u4f4d\u5230\u7684\u7f6a\u9b41\u7978\u9996\u662f\u2014\u2014\u51e0\u4e2a\u7ebf\u7a0b\u540c\u65f6\u5f80\u4e00\u4e2a HashMap \u91cc\u5199\u6570\u636e&#xff0c;\u89e6\u53d1\u4e86\u6269\u5bb9&#xff0c;\u7136\u540e\u5f62\u6210\u4e86\u6b7b\u5faa\u73af\u3002<\/p>\n<p>\u5bf9&#xff0c;\u4f60\u6ca1\u770b\u9519\u3002HashMap \u5728\u591a\u7ebf\u7a0b\u6269\u5bb9\u7684\u65f6\u5019&#xff0c;\u4f1a\u5f62\u6210\u94fe\u8868\u6b7b\u5faa\u73af&#xff0c;\u7136\u540e CPU \u5c31\u6c38\u8fdc\u8f6c\u5708\u5708\u4e86&#xff0c;\u6c38\u4e0d\u505c\u6b62&#xff0c;\u582a\u79f0\u6b7b\u4ea1\u87ba\u65cb\u3002<\/p>\n<p>\u90a3\u662f JDK 1.7 \u7684\u5e74\u4ee3\u3002<\/p>\n<p>\u540e\u6765\u5347\u5230 JDK 1.8&#xff0c;\u8fd9\u4e2a\u95ee\u9898\u6d88\u5931\u4e86&#xff0c;\u4f46\u5e76\u4e0d\u662f\u8bf4 HashMap \u5c31\u7ebf\u7a0b\u5b89\u5168\u4e86\u2014\u2014\u5b83\u53ea\u662f\u6362\u4e86\u4e00\u79cd\u65b9\u5f0f&#034;\u5751&#034;\u4f60\u3002<\/p>\n<p>\u6240\u4ee5\u8fd9\u7bc7\u6587\u7ae0\u5c31\u662f\u6211\u5728\u8e29\u5b8c\u8fd9\u4e9b\u5751\u3001\u7ffb\u5b8c OpenJDK \u6e90\u7801\u4e4b\u540e&#xff0c;\u7528\u6211\u81ea\u5df1\u7684\u8bdd&#xff0c;\u628a JDK 1.7 \u548c JDK 1.8 \u7684 HashMap \u5230\u5e95\u6709\u54ea\u4e9b\u533a\u522b\u3001\u4e3a\u4ec0\u4e48\u8981\u6539\u3001\u6539\u4e86\u4e4b\u540e\u6709\u4ec0\u4e48\u5f71\u54cd&#xff0c;\u5168\u90fd\u8bb2\u6e05\u695a\u3002<\/p>\n<p>\u9002\u5408\u4eba\u7fa4&#xff1a;<\/p>\n<ul>\n<li>\u521a\u63a5\u89e6 Java \u96c6\u5408\u6846\u67b6\u3001\u542c\u8bf4\u8fc7 HashMap \u4f46\u6ca1\u6df1\u5165\u7814\u7a76\u7684\u540c\u5b66<\/li>\n<li>\u9762\u8bd5\u524d\u4e34\u65f6\u62b1\u4f5b\u811a\u60f3\u641e\u6e05\u695a\u8fd9\u9053\u7ecf\u5178\u9898\u7684\u540c\u5b66<\/li>\n<li>\u50cf\u6211\u4e00\u6837\u5728\u751f\u4ea7\u73af\u5883\u8e29\u8fc7\u5751\u3001\u60f3\u5f7b\u5e95\u641e\u660e\u767d\u5e95\u5c42\u539f\u56e0\u7684\u540c\u5b66<\/li>\n<\/ul>\n<p>\u5168\u6587\u4f1a\u4ece\u6570\u636e\u7ed3\u6784\u3001\u54c8\u5e0c\u7b97\u6cd5\u3001\u63d2\u5165\u65b9\u5f0f\u3001\u6269\u5bb9\u673a\u5236\u3001\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\u4e94\u4e2a\u7ef4\u5ea6\u5c55\u5f00&#xff0c;\u6bcf\u4e2a\u7ef4\u5ea6\u90fd\u4f1a\u6709\u4ee3\u7801\u548c\u56fe\u89e3\u8f85\u52a9\u3002\u51c6\u5907\u597d\u4e86&#xff0c;\u54b1\u4eec\u5f00\u59cb\u3002<\/p>\n<h3>\u4e00\u3001\u5148\u641e\u6e05\u695a HashMap \u7684\u57fa\u672c\u9aa8\u67b6<\/h3>\n<p>\u5728\u804a 1.7 \u548c 1.8 \u7684\u533a\u522b\u4e4b\u524d&#xff0c;\u5148\u628a HashMap \u7684\u57fa\u672c\u8bbe\u8ba1\u903b\u8f91\u68b3\u7406\u4e00\u904d&#xff0c;\u4e0d\u7136\u540e\u9762\u8bb2\u53d8\u5316\u7684\u65f6\u5019\u5bb9\u6613\u6478\u4e0d\u7740\u5934\u8111\u3002<\/p>\n<h4>1.1 HashMap \u662f\u4e2a\u4ec0\u4e48\u4e1c\u897f&#xff1f;<\/h4>\n<p>\u8bf4\u4eba\u8bdd\u5c31\u662f&#xff1a;\u4e00\u4e2a\u5141\u8bb8\u4f60\u7528\u4efb\u610f\u7c7b\u578b\u7684\u952e\u6765\u5b58\u53d6\u503c\u7684\u5bb9\u5668&#xff0c;\u5e95\u5c42\u901a\u8fc7\u54c8\u5e0c\u8868\u5b9e\u73b0\u5feb\u901f\u7684\u5b58\u53d6\u64cd\u4f5c&#xff0c;\u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6\u662f O(1)\u3002<\/p>\n<p>\u7528\u751f\u6d3b\u5316\u7684\u6bd4\u55bb\u6765\u8bf4&#xff0c;\u4f60\u53ef\u4ee5\u628a HashMap \u60f3\u8c61\u6210\u4e00\u4e2a\u8d85\u5927\u578b\u7684\u5feb\u9012\u67dc&#xff1a;<\/p>\n<ul>\n<li>\u6bcf\u4e2a\u683c\u5b50\u6709\u4e00\u4e2a\u7f16\u53f7&#xff08;\u6570\u7ec4\u4e0b\u6807&#xff09;<\/li>\n<li>\u4f60\u5bc4\u5feb\u9012\u7684\u65f6\u5019&#xff0c;\u7cfb\u7edf\u6839\u636e\u4f60\u7684\u624b\u673a\u53f7&#xff08;\u952e&#xff09;\u7b97\u51fa\u4e00\u4e2a\u683c\u5b50\u7f16\u53f7&#xff08;\u54c8\u5e0c\u503c&#xff09;&#xff0c;\u7136\u540e\u628a\u5feb\u9012\u653e\u8fdb\u53bb<\/li>\n<li>\u53d6\u7684\u65f6\u5019\u4e00\u6837&#xff0c;\u8f93\u5165\u624b\u673a\u53f7&#xff0c;\u7b97\u51fa\u683c\u5b50\u7f16\u53f7&#xff0c;\u76f4\u63a5\u5f00\u67dc<\/li>\n<\/ul>\n<p>\u4f46\u95ee\u9898\u6765\u4e86&#xff1a;\u4e0d\u540c\u7684\u624b\u673a\u53f7\u53ef\u80fd\u7b97\u51fa\u540c\u4e00\u4e2a\u683c\u5b50\u7f16\u53f7\u2014\u2014\u8fd9\u5c31\u662f\u54c8\u5e0c\u51b2\u7a81&#xff08;Hash Collision&#xff09;\u3002<\/p>\n<p>\u89e3\u51b3\u54c8\u5e0c\u51b2\u7a81\u7684\u65b9\u5f0f&#xff0c;HashMap \u7528\u7684\u662f\u94fe\u5730\u5740\u6cd5&#xff08;Separate Chaining&#xff09;\u2014\u2014\u540c\u4e00\u4e2a\u683c\u5b50\u91cc\u653e\u4e0d\u4e0b\u4e86&#xff0c;\u5c31\u5728\u683c\u5b50\u540e\u9762\u6302\u4e00\u6761\u94fe\u8868&#xff0c;\u65b0\u6765\u7684\u5f80\u94fe\u8868\u4e0a\u52a0\u3002<\/p>\n<p>\u8fd9\u662f HashMap \u7684\u57fa\u7840\u903b\u8f91&#xff0c;\u5728 JDK 1.7 \u548c 1.8 \u4e2d\u90fd\u4e00\u6837&#xff0c;\u533a\u522b\u5728\u4e8e&#xff1a;\u5f53\u94fe\u8868\u8d8a\u6765\u8d8a\u957f\u7684\u65f6\u5019&#xff0c;\u8be5\u600e\u4e48\u5904\u7406&#xff1f;<\/p>\n<h3>\u4e8c\u3001JDK 1.7 \u7684\u5b9e\u73b0&#xff1a;\u6570\u7ec4 &#043; \u94fe\u8868<\/h3>\n<h4>2.1 \u6570\u636e\u7ed3\u6784<\/h4>\n<p>JDK 1.7 \u7684 HashMap&#xff0c;\u5e95\u5c42\u662f\u4e00\u4e2a Entry&lt;K, V&gt;[] \u6570\u7ec4&#xff0c;\u6bcf\u4e2a Entry \u662f\u94fe\u8868\u7684\u8282\u70b9&#xff0c;\u5305\u542b key\u3001value\u3001hash\u3001next \u56db\u4e2a\u5b57\u6bb5\u3002<\/p>\n<p>  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.edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-w23QN7Q19v1N7fZk .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-w23QN7Q19v1N7fZk .marker{fill:#333333;stroke:#333333;}#mermaid-svg-w23QN7Q19v1N7fZk .marker.cross{stroke:#333333;}#mermaid-svg-w23QN7Q19v1N7fZk svg{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-w23QN7Q19v1N7fZk p{margin:0;}#mermaid-svg-w23QN7Q19v1N7fZk .label{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;color:#333;}#mermaid-svg-w23QN7Q19v1N7fZk .cluster-label text{fill:#333;}#mermaid-svg-w23QN7Q19v1N7fZk .cluster-label span{color:#333;}#mermaid-svg-w23QN7Q19v1N7fZk .cluster-label span p{background-color:transparent;}#mermaid-svg-w23QN7Q19v1N7fZk .label text,#mermaid-svg-w23QN7Q19v1N7fZk span{fill:#333;color:#333;}#mermaid-svg-w23QN7Q19v1N7fZk .node rect,#mermaid-svg-w23QN7Q19v1N7fZk .node circle,#mermaid-svg-w23QN7Q19v1N7fZk .node ellipse,#mermaid-svg-w23QN7Q19v1N7fZk .node polygon,#mermaid-svg-w23QN7Q19v1N7fZk .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-w23QN7Q19v1N7fZk .rough-node .label text,#mermaid-svg-w23QN7Q19v1N7fZk .node .label text,#mermaid-svg-w23QN7Q19v1N7fZk .image-shape .label,#mermaid-svg-w23QN7Q19v1N7fZk .icon-shape .label{text-anchor:middle;}#mermaid-svg-w23QN7Q19v1N7fZk .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-w23QN7Q19v1N7fZk .rough-node .label,#mermaid-svg-w23QN7Q19v1N7fZk .node .label,#mermaid-svg-w23QN7Q19v1N7fZk .image-shape .label,#mermaid-svg-w23QN7Q19v1N7fZk .icon-shape .label{text-align:center;}#mermaid-svg-w23QN7Q19v1N7fZk .node.clickable{cursor:pointer;}#mermaid-svg-w23QN7Q19v1N7fZk .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-w23QN7Q19v1N7fZk .arrowheadPath{fill:#333333;}#mermaid-svg-w23QN7Q19v1N7fZk .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-w23QN7Q19v1N7fZk .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-w23QN7Q19v1N7fZk .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-w23QN7Q19v1N7fZk .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-w23QN7Q19v1N7fZk .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-w23QN7Q19v1N7fZk .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-w23QN7Q19v1N7fZk .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-w23QN7Q19v1N7fZk .cluster text{fill:#333;}#mermaid-svg-w23QN7Q19v1N7fZk .cluster span{color:#333;}#mermaid-svg-w23QN7Q19v1N7fZk div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-w23QN7Q19v1N7fZk .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-w23QN7Q19v1N7fZk rect.text{fill:none;stroke-width:0;}#mermaid-svg-w23QN7Q19v1N7fZk .icon-shape,#mermaid-svg-w23QN7Q19v1N7fZk .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-w23QN7Q19v1N7fZk .icon-shape p,#mermaid-svg-w23QN7Q19v1N7fZk .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-w23QN7Q19v1N7fZk .icon-shape .label rect,#mermaid-svg-w23QN7Q19v1N7fZk .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-w23QN7Q19v1N7fZk .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-w23QN7Q19v1N7fZk .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-w23QN7Q19v1N7fZk :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>HashMap\u5185\u90e8\u6570\u7ec4 table[]<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>table[0]: null<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>table[1]: Entry{k1,v1}<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>table[2]: Entry{k2,v2} -&gt; Entry{k3,v3} -&gt; Entry{k4,v4}<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>table[3]: null<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>table[4]: Entry{k5,v5} -&gt; Entry{k6,v6}<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>&#8230;<\/p>\n<p><\/span><\/p>\n<p>\u8fd9\u5f20\u56fe\u5c31\u662f JDK 1.7 HashMap \u7684\u771f\u5b9e\u72b6\u6001&#xff1a;\u5927\u90e8\u5206\u4f4d\u7f6e\u662f null&#xff0c;\u6709\u4e9b\u4f4d\u7f6e\u53ea\u6302\u4e86\u4e00\u4e2a\u8282\u70b9&#xff0c;\u6709\u4e9b\u4f4d\u7f6e\u56e0\u4e3a\u54c8\u5e0c\u51b2\u7a81&#xff0c;\u6302\u4e86\u4e00\u6761\u957f\u957f\u7684\u94fe\u8868\u3002<\/p>\n<h4>2.2 \u54c8\u5e0c\u7b97\u6cd5&#xff1a;\u5bf9\u6270\u52a8\u51fd\u6570\u7684\u6267\u5ff5<\/h4>\n<p>JDK 1.7 \u5bf9 key \u7684 hashCode \u505a\u4e86\u56db\u6b21\u6270\u52a8&#xff0c;\u76ee\u7684\u662f\u8ba9\u54c8\u5e0c\u5206\u5e03\u66f4\u5747\u5300&#xff0c;\u51cf\u5c11\u51b2\u7a81&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.7 \u7684 hash \u65b9\u6cd5<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">hash<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> h<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    h <span class=\"token operator\">^&#061;<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">20<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">^<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">12<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> h <span class=\"token operator\">^<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">7<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">^<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">4<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u7136\u540e\u901a\u8fc7\u8fd9\u4e2a\u65b9\u6cd5\u8ba1\u7b97\u6570\u7ec4\u4e0b\u6807<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">indexFor<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> h<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">int<\/span> length<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> h <span class=\"token operator\">&amp;<\/span> <span class=\"token punctuation\">(<\/span>length <span class=\"token operator\">&#8211;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7b49\u4ef7\u4e8e h % length&#xff0c;\u4f46\u4f4d\u8fd0\u7b97\u66f4\u5feb<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u8bf4\u5b9e\u8bdd&#xff0c;\u7b2c\u4e00\u6b21\u770b\u5230\u8fd9\u6bb5\u4ee3\u7801\u7684\u65f6\u5019\u6211\u662f\u61f5\u7684\u3002\u8fd9\u51e0\u4e2a\u53f3\u79fb\u548c\u5f02\u6216\u64cd\u4f5c&#xff0c;\u7c97\u770b\u50cf\u662f\u4e71\u5199\u7684&#xff0c;\u5176\u5b9e\u80cc\u540e\u662f\u6709\u6570\u5b66\u4f9d\u636e\u7684\u2014\u2014\u901a\u8fc7\u591a\u6b21\u79fb\u4f4d\u548c\u5f02\u6216&#xff0c;\u628a\u9ad8\u4f4d\u7684\u4fe1\u606f&#034;\u6df7\u5165&#034;\u4f4e\u4f4d&#xff0c;\u8fd9\u6837\u5728 &amp; (length &#8211; 1) \u7684\u65f6\u5019&#xff0c;\u9ad8\u4f4d\u4fe1\u606f\u4e5f\u80fd\u53c2\u4e0e\u5230\u4e0b\u6807\u8ba1\u7b97\u4e2d&#xff0c;\u51cf\u5c11\u78b0\u649e\u6982\u7387\u3002<\/p>\n<h4>2.3 \u63d2\u5165\u65b9\u5f0f&#xff1a;\u5934\u63d2\u6cd5<\/h4>\n<p>JDK 1.7 \u5f80\u94fe\u8868\u91cc\u63d2\u5165\u65b0\u8282\u70b9&#xff0c;\u7528\u7684\u662f\u5934\u63d2\u6cd5\u2014\u2014\u6bcf\u6b21\u90fd\u628a\u65b0\u8282\u70b9\u653e\u5230\u94fe\u8868\u7684\u5934\u90e8&#xff0c;\u539f\u6709\u7684\u8282\u70b9\u5f80\u540e\u632a\u3002<\/p>\n<p>\u4e3a\u4ec0\u4e48\u7528\u5934\u63d2\u6cd5&#xff1f;\u5f53\u5e74\u7684\u8bbe\u8ba1\u8005\u89c9\u5f97&#xff1a;\u65b0\u63d2\u5165\u7684\u6570\u636e\u88ab\u8bbf\u95ee\u7684\u6982\u7387\u66f4\u9ad8&#xff08;\u5c40\u90e8\u6027\u539f\u7406&#xff09;&#xff0c;\u653e\u5728\u5934\u90e8\u53ef\u4ee5\u66f4\u5feb\u88ab\u627e\u5230\u3002<\/p>\n<p>\u8fd9\u4e2a\u903b\u8f91\u542c\u8d77\u6765\u6ca1\u95ee\u9898&#xff0c;\u4f46\u95ee\u9898\u85cf\u5728\u6269\u5bb9\u7684\u65f6\u5019\u2026\u2026\u7b49\u6211\u4eec\u8bb2\u5230\u591a\u7ebf\u7a0b\u95ee\u9898\u90a3\u8282\u518d\u5c55\u5f00\u3002<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.7 \u7684 addEntry \u548c createEntry&#xff08;\u7b80\u5316\u7248&#xff09;<\/span><br \/>\n<span class=\"token keyword\">void<\/span> <span class=\"token function\">addEntry<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> hash<span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">K<\/span> key<span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">V<\/span> value<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">int<\/span> bucketIndex<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>size <span class=\"token operator\">&gt;&#061;<\/span> threshold<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&amp;&amp;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">null<\/span> <span class=\"token operator\">!&#061;<\/span> table<span class=\"token punctuation\">[<\/span>bucketIndex<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token function\">resize<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">2<\/span> <span class=\"token operator\">*<\/span> table<span class=\"token punctuation\">.<\/span>length<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u6269\u5bb9<\/span><br \/>\n        <span class=\"token comment\">\/\/ &#8230;\u91cd\u65b0\u8ba1\u7b97 hash \u548c bucketIndex<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token function\">createEntry<\/span><span class=\"token punctuation\">(<\/span>hash<span class=\"token punctuation\">,<\/span> key<span class=\"token punctuation\">,<\/span> value<span class=\"token punctuation\">,<\/span> bucketIndex<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token keyword\">void<\/span> <span class=\"token function\">createEntry<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> hash<span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">K<\/span> key<span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">V<\/span> value<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">int<\/span> bucketIndex<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token class-name\">Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> e <span class=\"token operator\">&#061;<\/span> table<span class=\"token punctuation\">[<\/span>bucketIndex<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token comment\">\/\/ \u5934\u63d2\u6cd5&#xff1a;\u65b0\u8282\u70b9\u7684 next \u6307\u5411\u539f\u6765\u7684\u5934\u8282\u70b9<\/span><br \/>\n    table<span class=\"token punctuation\">[<\/span>bucketIndex<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span>hash<span class=\"token punctuation\">,<\/span> key<span class=\"token punctuation\">,<\/span> value<span class=\"token punctuation\">,<\/span> e<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    size<span class=\"token operator\">&#043;&#043;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>2.4 \u6269\u5bb9\u673a\u5236<\/h4>\n<p>JDK 1.7 \u6269\u5bb9\u7684\u89e6\u53d1\u6761\u4ef6&#xff1a;\u5f53 size &gt;&#061; threshold&#xff08;threshold &#061; capacity \u00d7 loadFactor&#xff0c;\u9ed8\u8ba4 16 \u00d7 0.75 &#061; 12&#xff09;\u4e14\u5f53\u524d bucket \u975e\u7a7a\u65f6&#xff0c;\u89e6\u53d1\u6269\u5bb9&#xff0c;\u5bb9\u91cf\u7ffb\u500d\u3002<\/p>\n<p>\u6269\u5bb9\u65f6&#xff0c;\u6bcf\u4e00\u4e2a\u5143\u7d20\u90fd\u8981\u91cd\u65b0\u8ba1\u7b97\u54c8\u5e0c\u503c\u548c\u65b0\u6570\u7ec4\u4e0b\u6807&#xff0c;\u7136\u540e\u518d\u628a\u5143\u7d20\u91cd\u65b0\u63d2\u5165\u65b0\u6570\u7ec4\u3002\u8fd9\u4e2a\u8fc7\u7a0b\u53eb rehash\u3002<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.7 \u7684 transfer \u65b9\u6cd5&#xff08;\u6269\u5bb9\u6838\u5fc3\u903b\u8f91&#xff0c;\u7b80\u5316\u7248&#xff09;<\/span><br \/>\n<span class=\"token keyword\">void<\/span> <span class=\"token function\">transfer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Entry<\/span><span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span> newTable<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">boolean<\/span> rehash<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">int<\/span> newCapacity <span class=\"token operator\">&#061;<\/span> newTable<span class=\"token punctuation\">.<\/span>length<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> e <span class=\"token operator\">:<\/span> table<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">while<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">null<\/span> <span class=\"token operator\">!&#061;<\/span> e<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token class-name\">Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> next <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">.<\/span>next<span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>rehash<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n                e<span class=\"token punctuation\">.<\/span>hash <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">&#061;&#061;<\/span> e<span class=\"token punctuation\">.<\/span>key <span class=\"token operator\">?<\/span> <span class=\"token number\">0<\/span> <span class=\"token operator\">:<\/span> <span class=\"token function\">hash<\/span><span class=\"token punctuation\">(<\/span>e<span class=\"token punctuation\">.<\/span>key<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token punctuation\">}<\/span><br \/>\n            <span class=\"token keyword\">int<\/span> i <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">indexFor<\/span><span class=\"token punctuation\">(<\/span>e<span class=\"token punctuation\">.<\/span>hash<span class=\"token punctuation\">,<\/span> newCapacity<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token comment\">\/\/ \u5934\u63d2\u6cd5&#xff01;\u65b0\u6570\u7ec4\u91cc\u4e5f\u662f\u5934\u63d2<\/span><br \/>\n            e<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> newTable<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            newTable<span class=\"token punctuation\">[<\/span>i<span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n            e <span class=\"token operator\">&#061;<\/span> next<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u6ce8\u610f\u90a3\u4e2a\u5934\u63d2\u6cd5\u2014\u2014\u5355\u7ebf\u7a0b\u4e0b\u6ca1\u95ee\u9898&#xff0c;\u591a\u7ebf\u7a0b\u4e0b\u8fd9\u5c31\u662f\u707e\u96be\u7684\u8d77\u6e90\u3002\u540e\u9762\u91cd\u70b9\u8bb2\u3002<\/p>\n<h3>\u4e09\u3001JDK 1.8 \u7684\u8fdb\u5316&#xff1a;\u6570\u7ec4 &#043; \u94fe\u8868 &#043; \u7ea2\u9ed1\u6811<\/h3>\n<h4>3.1 \u6700\u5927\u7684\u53d8\u5316&#xff1a;\u5f15\u5165\u7ea2\u9ed1\u6811<\/h4>\n<p>JDK 1.8 \u5bf9 HashMap \u505a\u4e86\u91cd\u5927\u91cd\u6784&#xff0c;\u6700\u663e\u773c\u7684\u53d8\u5316\u662f&#xff1a;\u5f53\u94fe\u8868\u957f\u5ea6\u8d85\u8fc7 8&#xff0c;\u4e14\u6570\u7ec4\u957f\u5ea6\u8fbe\u5230 64 \u65f6&#xff0c;\u94fe\u8868\u4f1a\u8f6c\u6362\u6210\u7ea2\u9ed1\u6811\u3002<\/p>\n<p>\u4e3a\u4ec0\u4e48\u8981\u5f15\u5165\u7ea2\u9ed1\u6811&#xff1f;<\/p>\n<p>\u94fe\u8868\u67e5\u627e\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u662f O(n)&#xff0c;\u5982\u679c\u54c8\u5e0c\u51b2\u7a81\u4e25\u91cd&#xff0c;\u94fe\u8868\u8d8a\u6765\u8d8a\u957f&#xff0c;\u6027\u80fd\u5c31\u8d8a\u6765\u8d8a\u5dee\u3002\u7ea2\u9ed1\u6811\u7684\u67e5\u627e\u590d\u6742\u5ea6\u662f O(log n)&#xff0c;\u5728\u94fe\u8868\u6bd4\u8f83\u957f\u7684\u573a\u666f\u4e0b&#xff0c;\u6027\u80fd\u63d0\u5347\u975e\u5e38\u660e\u663e\u3002<\/p>\n<p>\u4f46\u662f\u7ea2\u9ed1\u6811\u7684\u7ef4\u62a4\u6210\u672c\u4e5f\u6bd4\u94fe\u8868\u9ad8&#xff0c;\u8282\u70b9\u6570\u5c11\u7684\u65f6\u5019&#xff0c;\u7528\u94fe\u8868\u53cd\u800c\u66f4\u8f7b\u91cf\u3002\u6240\u4ee5 JDK 1.8 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p,#mermaid-svg-sPSczN3gMryh8YA2 .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-sPSczN3gMryh8YA2 .icon-shape .label rect,#mermaid-svg-sPSczN3gMryh8YA2 .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-sPSczN3gMryh8YA2 .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-sPSczN3gMryh8YA2 .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-sPSczN3gMryh8YA2 :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u662f<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u5426<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u662f<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u5426<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u662f<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u5426<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u662f<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>\u5426<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>put(key, value)<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u8ba1\u7b97\u54c8\u5e0c\u503c\u786e\u5b9abucket\u4f4d\u7f6e<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>bucket\u662f\u5426\u4e3a\u7a7a?<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u76f4\u63a5\u63d2\u5165\u8282\u70b9<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u5f53\u524d\u8282\u70b9\u662f\u7ea2\u9ed1\u6811\u8282\u70b9?<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u6309\u7ea2\u9ed1\u6811\u65b9\u5f0f\u63d2\u5165<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u904d\u5386\u94fe\u8868<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u627e\u5230\u76f8\u540ckey?<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u66f4\u65b0value<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u94fe\u8868\u5c3e\u90e8\u63d2\u5165<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u94fe\u8868\u957f\u5ea6 &gt;&#061; 8\u4e14\u6570\u7ec4\u957f\u5ea6 &gt;&#061; 64?<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u94fe\u8868\u8f6c\u7ea2\u9ed1\u6811 treeifyBin()<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u4fdd\u6301\u94fe\u8868\u7ed3\u6784<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>size&#043;&#043;&#xff0c;\u68c0\u67e5\u662f\u5426\u9700\u8981\u6269\u5bb9<\/p>\n<p><\/span><\/p>\n<h4>3.2 \u6570\u636e\u7ed3\u6784\u53d8\u5316<\/h4>\n<p>\u8282\u70b9\u7c7b\u578b\u4ece Entry \u53d8\u6210\u4e86 Node&#xff08;\u6b63\u5e38\u60c5\u51b5&#xff09;\u548c TreeNode&#xff08;\u6811\u5316\u4e4b\u540e&#xff09;&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u7684 Node \u7c7b<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">Node<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> <span class=\"token keyword\">implements<\/span> <span class=\"token class-name\">Map<span class=\"token punctuation\">.<\/span>Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span> hash<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">final<\/span> <span class=\"token class-name\">K<\/span> key<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token class-name\">V<\/span> value<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token class-name\">Node<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> next<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token comment\">\/\/ &#8230;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u7684 TreeNode \u7c7b&#xff08;\u7ee7\u627f\u81ea LinkedHashMap.Entry&#xff0c;\u518d\u7ee7\u627f\u81ea Node&#xff09;<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">TreeNode<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> <span class=\"token keyword\">extends<\/span> <span class=\"token class-name\">LinkedHashMap<span class=\"token punctuation\">.<\/span>Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token class-name\">TreeNode<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> parent<span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7236\u8282\u70b9<\/span><br \/>\n    <span class=\"token class-name\">TreeNode<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> left<span class=\"token punctuation\">;<\/span>    <span class=\"token comment\">\/\/ \u5de6\u5b50\u8282\u70b9<\/span><br \/>\n    <span class=\"token class-name\">TreeNode<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> right<span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u53f3\u5b50\u8282\u70b9<\/span><br \/>\n    <span class=\"token class-name\">TreeNode<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">K<\/span><span class=\"token punctuation\">,<\/span><span class=\"token class-name\">V<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> prev<span class=\"token punctuation\">;<\/span>    <span class=\"token comment\">\/\/ \u7528\u4e8e\u5220\u9664\u65f6\u7ef4\u62a4\u94fe\u8868<\/span><br \/>\n    <span class=\"token keyword\">boolean<\/span> red<span class=\"token punctuation\">;<\/span>           <span class=\"token comment\">\/\/ \u989c\u8272\u6807\u5fd7<\/span><br \/>\n    <span class=\"token comment\">\/\/ &#8230;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>3.3 \u54c8\u5e0c\u7b97\u6cd5\u7b80\u5316<\/h4>\n<p>JDK 1.8 \u628a\u539f\u6765\u7684\u56db\u6b21\u6270\u52a8\u7b80\u5316\u6210\u4e86\u4e00\u6b21\u6270\u52a8&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u7684 hash \u65b9\u6cd5<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">hash<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Object<\/span> key<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">int<\/span> h<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">(<\/span>key <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">?<\/span> <span class=\"token number\">0<\/span> <span class=\"token operator\">:<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&#061;<\/span> key<span class=\"token punctuation\">.<\/span><span class=\"token function\">hashCode<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">^<\/span> <span class=\"token punctuation\">(<\/span>h <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">16<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u53ea\u505a\u4e86\u4e00\u6b21\u53f3\u79fb 16 \u4f4d\u518d\u5f02\u6216\u3002\u4e3a\u4ec0\u4e48\u591f\u7528\u4e86&#xff1f;\u56e0\u4e3a JDK 1.8 \u5f15\u5165\u4e86\u7ea2\u9ed1\u6811&#xff0c;\u5373\u4f7f\u51b2\u7a81\u7a0d\u591a\u4e00\u70b9&#xff0c;\u4e5f\u80fd\u4fdd\u8bc1\u67e5\u8be2\u6027\u80fd&#xff0c;\u4e0d\u9700\u8981\u50cf 1.7 \u90a3\u6837\u7528\u590d\u6742\u7684\u6270\u52a8\u6765\u6781\u529b\u51cf\u5c11\u51b2\u7a81\u3002<\/p>\n<p>\u53e6\u5916&#xff0c;null \u952e\u4f1a\u88ab\u6620\u5c04\u5230\u4e0b\u6807 0&#xff0c;\u8fd9\u4e00\u70b9\u4e24\u4e2a\u7248\u672c\u90fd\u4e00\u6837\u3002<\/p>\n<h4>3.4 \u63d2\u5165\u65b9\u5f0f&#xff1a;\u5c3e\u63d2\u6cd5<\/h4>\n<p>\u8fd9\u662f JDK 1.8 \u4e00\u4e2a\u975e\u5e38\u5173\u952e\u7684\u6539\u53d8&#xff1a;\u94fe\u8868\u7684\u63d2\u5165\u65b9\u5f0f\u4ece\u5934\u63d2\u6cd5\u6539\u6210\u4e86\u5c3e\u63d2\u6cd5\u3002<\/p>\n<p>\u65b0\u8282\u70b9\u4e0d\u518d\u63d2\u5230\u94fe\u8868\u5934\u90e8&#xff0c;\u800c\u662f\u63d2\u5230\u94fe\u8868\u5c3e\u90e8\u3002\u8fd9\u4e2a\u6539\u53d8\u770b\u4f3c\u5fae\u5c0f&#xff0c;\u5374\u76f4\u63a5\u89e3\u51b3\u4e86\u591a\u7ebf\u7a0b\u6269\u5bb9\u65f6\u6b7b\u5faa\u73af\u7684\u95ee\u9898&#xff08;\u867d\u7136\u5e76\u6ca1\u6709\u8ba9 HashMap \u53d8\u6210\u7ebf\u7a0b\u5b89\u5168\u7684&#xff0c;\u4f46\u81f3\u5c11\u4e0d\u4f1a\u6b7b\u5faa\u73af\u4e86&#xff09;\u3002<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u7684 putVal \u65b9\u6cd5&#xff08;\u94fe\u8868\u63d2\u5165\u90e8\u5206&#xff0c;\u7b80\u5316\u7248&#xff09;<\/span><br \/>\n<span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> binCount <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token punctuation\">;<\/span> <span class=\"token operator\">&#043;&#043;<\/span>binCount<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>e <span class=\"token operator\">&#061;<\/span> p<span class=\"token punctuation\">.<\/span>next<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u5c3e\u63d2\u6cd5&#xff01;<\/span><br \/>\n        p<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">newNode<\/span><span class=\"token punctuation\">(<\/span>hash<span class=\"token punctuation\">,<\/span> key<span class=\"token punctuation\">,<\/span> value<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>binCount <span class=\"token operator\">&gt;&#061;<\/span> <span class=\"token constant\">TREEIFY_THRESHOLD<\/span> <span class=\"token operator\">&#8211;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token comment\">\/\/ TREEIFY_THRESHOLD &#061; 8<\/span><br \/>\n            <span class=\"token function\">treeifyBin<\/span><span class=\"token punctuation\">(<\/span>tab<span class=\"token punctuation\">,<\/span> hash<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u8f6c\u7ea2\u9ed1\u6811<\/span><br \/>\n        <span class=\"token keyword\">break<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>e<span class=\"token punctuation\">.<\/span>hash <span class=\"token operator\">&#061;&#061;<\/span> hash <span class=\"token operator\">&amp;&amp;<\/span><br \/>\n        <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>k <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">.<\/span>key<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> key <span class=\"token operator\">||<\/span> <span class=\"token punctuation\">(<\/span>key <span class=\"token operator\">!&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">&amp;&amp;<\/span> key<span class=\"token punctuation\">.<\/span><span class=\"token function\">equals<\/span><span class=\"token punctuation\">(<\/span>k<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><br \/>\n        <span class=\"token keyword\">break<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    p <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h4>3.5 \u6269\u5bb9\u4f18\u5316&#xff1a;\u9ad8\u4f4e\u4f4d\u62c6\u5206<\/h4>\n<p>JDK 1.8 \u6269\u5bb9\u65f6\u6709\u4e00\u4e2a\u975e\u5e38\u7cbe\u5999\u7684\u4f18\u5316&#xff0c;\u4e0d\u518d\u9700\u8981\u50cf 1.7 \u90a3\u6837\u6bcf\u4e2a\u5143\u7d20\u90fd\u91cd\u65b0\u8ba1\u7b97\u54c8\u5e0c\u503c\u3002<\/p>\n<p>\u903b\u8f91\u662f\u8fd9\u6837\u7684&#xff1a;\u6570\u7ec4\u5bb9\u91cf\u59cb\u7ec8\u662f 2 \u7684\u5e42\u6b21&#xff08;\u8bbe\u539f\u5bb9\u91cf\u4e3a n&#xff09;&#xff0c;\u6269\u5bb9\u540e\u53d8\u6210 2n\u3002\u5143\u7d20\u5728\u65b0\u6570\u7ec4\u4e2d\u7684\u4f4d\u7f6e&#xff0c;\u8981\u4e48\u8fd8\u5728\u539f\u6765\u7684\u4e0b\u6807 i&#xff0c;\u8981\u4e48\u5728 i &#043; n\u3002\u5224\u65ad\u7684\u4f9d\u636e\u662f\u5143\u7d20\u7684\u54c8\u5e0c\u503c\u7684\u7b2c log2(n) &#043; 1 \u4f4d&#xff08;\u4e5f\u5c31\u662f\u65b0\u589e\u7684\u90a3\u4e00\u4f4d\u63a9\u7801\u4f4d&#xff09;\u662f 0 \u8fd8\u662f 1\u3002<\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u6269\u5bb9\u7684\u6838\u5fc3\u5224\u65ad\u903b\u8f91&#xff08;\u7b80\u5316\u7248&#xff09;<\/span><br \/>\n<span class=\"token comment\">\/\/ e.hash &amp; oldCap \u5982\u679c\u4e3a 0&#xff0c;\u65b0\u4e0b\u6807 &#061; \u539f\u4e0b\u6807<\/span><br \/>\n<span class=\"token comment\">\/\/ e.hash &amp; oldCap \u5982\u679c\u4e3a 1&#xff0c;\u65b0\u4e0b\u6807 &#061; \u539f\u4e0b\u6807 &#043; oldCap<\/span><br \/>\n<span class=\"token keyword\">do<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    next <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">.<\/span>next<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>e<span class=\"token punctuation\">.<\/span>hash <span class=\"token operator\">&amp;<\/span> oldCap<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u653e\u5230\u4f4e\u4f4d\u94fe\u8868&#xff08;lo \u94fe\u8868&#xff09;&#xff0c;\u4f4d\u7f6e\u4e0d\u53d8<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>loTail <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span> loHead <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">else<\/span> loTail<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n        loTail <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">else<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u653e\u5230\u9ad8\u4f4d\u94fe\u8868&#xff08;hi \u94fe\u8868&#xff09;&#xff0c;\u4f4d\u7f6e &#061; \u539f\u4f4d\u7f6e &#043; \u539f\u5bb9\u91cf<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>hiTail <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span> hiHead <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">else<\/span> hiTail<span class=\"token punctuation\">.<\/span>next <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n        hiTail <span class=\"token operator\">&#061;<\/span> e<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>e <span class=\"token operator\">&#061;<\/span> next<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">!&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>\u8fd9\u4e2a\u4f18\u5316\u6709\u4e24\u4e2a\u597d\u5904&#xff1a;<\/p>\n<li>\u4e0d\u9700\u8981\u91cd\u65b0\u8ba1\u7b97\u54c8\u5e0c\u503c&#xff0c;\u6027\u80fd\u66f4\u597d<\/li>\n<li>\u7ef4\u6301\u4e86\u94fe\u8868\u7684\u539f\u6709\u987a\u5e8f&#xff08;\u56e0\u4e3a\u662f\u5c3e\u63d2&#xff09;&#xff0c;\u4e0d\u4f1a\u51fa\u73b0\u94fe\u8868\u53cd\u8f6c<\/li>\n<p>  #mermaid-svg-oXzLtgA7fWqqC0WO{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes 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.flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-oXzLtgA7fWqqC0WO rect.text{fill:none;stroke-width:0;}#mermaid-svg-oXzLtgA7fWqqC0WO .icon-shape,#mermaid-svg-oXzLtgA7fWqqC0WO .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-oXzLtgA7fWqqC0WO .icon-shape p,#mermaid-svg-oXzLtgA7fWqqC0WO .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-oXzLtgA7fWqqC0WO .icon-shape .label rect,#mermaid-svg-oXzLtgA7fWqqC0WO .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-oXzLtgA7fWqqC0WO .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-oXzLtgA7fWqqC0WO .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-oXzLtgA7fWqqC0WO :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u6269\u5bb9\u540e capacity&#061;16<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>\u6269\u5bb9\u524d capacity&#061;8<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>hash &amp; 8 &#061;&#061; 0<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>hash &amp; 8 !&#061; 0<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"edgeLabel\"><\/p>\n<p>hash &amp; 8 !&#061; 0<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>index 0<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>hash:01001 key:A<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>hash:10001 key:B<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>hash:11001 key:C<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>index 0 (bit&#061;0)<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>key:A hash:01001<\/p>\n<p><\/span><\/p>\n<p>         <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>index 8 (bit&#061;1)<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>key:B hash:10001<\/p>\n<p><\/span><\/p>\n<p>         <span class=\"nodeLabel\"><\/p>\n<p>key:C hash:11001<\/p>\n<p><\/span><\/p>\n<h3>\u56db\u3001\u6838\u5fc3\u533a\u522b\u6c47\u603b\u5bf9\u6bd4<\/h3>\n<p>\u5230\u8fd9\u91cc&#xff0c;\u6838\u5fc3\u7684\u53d8\u5316\u5df2\u7ecf\u5168\u90e8\u8bb2\u5b8c\u4e86&#xff0c;\u6765\u4e2a\u8868\u683c\u5bf9\u6bd4\u4e00\u4e0b&#xff0c;\u65b9\u4fbf\u8bb0\u5fc6&#xff1a;<\/p>\n<table>\n<tr>\u5bf9\u6bd4\u7ef4\u5ea6JDK 1.7JDK 1.8<\/tr>\n<tbody>\n<tr>\n<td>\u5e95\u5c42\u6570\u636e\u7ed3\u6784<\/td>\n<td>\u6570\u7ec4 &#043; \u94fe\u8868<\/td>\n<td>\u6570\u7ec4 &#043; \u94fe\u8868 &#043; \u7ea2\u9ed1\u6811<\/td>\n<\/tr>\n<tr>\n<td>\u8282\u70b9\u7c7b\u578b<\/td>\n<td>Entry<\/td>\n<td>Node \/ TreeNode<\/td>\n<\/tr>\n<tr>\n<td>\u54c8\u5e0c\u6270\u52a8\u6b21\u6570<\/td>\n<td>4\u6b21&#xff08;\u590d\u6742\u6270\u52a8&#xff09;<\/td>\n<td>1\u6b21&#xff08;\u7b80\u5355\u6270\u52a8&#xff09;<\/td>\n<\/tr>\n<tr>\n<td>\u94fe\u8868\u63d2\u5165\u65b9\u5f0f<\/td>\n<td>\u5934\u63d2\u6cd5<\/td>\n<td>\u5c3e\u63d2\u6cd5<\/td>\n<\/tr>\n<tr>\n<td>\u6269\u5bb9 rehash<\/td>\n<td>\u6bcf\u4e2a\u5143\u7d20\u91cd\u65b0 hash<\/td>\n<td>\u9ad8\u4f4e\u4f4d\u62c6\u5206&#xff0c;\u65e0\u9700\u91cd\u65b0 hash<\/td>\n<\/tr>\n<tr>\n<td>\u6811\u5316\u9608\u503c<\/td>\n<td>\u65e0<\/td>\n<td>\u94fe\u8868\u957f\u5ea6 \u2265 8 \u4e14\u6570\u7ec4\u957f\u5ea6 \u2265 64<\/td>\n<\/tr>\n<tr>\n<td>\u9000\u5316\u4e3a\u94fe\u8868\u9608\u503c<\/td>\n<td>\u65e0<\/td>\n<td>\u6811\u8282\u70b9\u6570 \u2264 6 \u65f6\u9000\u5316<\/td>\n<\/tr>\n<tr>\n<td>\u5e76\u53d1\u6b7b\u5faa\u73af\u98ce\u9669<\/td>\n<td>\u6709&#xff08;\u6269\u5bb9\u65f6\u5934\u63d2\u5bfc\u81f4&#xff09;<\/td>\n<td>\u65e0&#xff08;\u4f46\u4ecd\u7136\u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168&#xff09;<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u4e94\u3001\u6700\u5bb9\u6613\u88ab\u5ffd\u89c6\u7684\u5751&#xff1a;\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898<\/h3>\n<p>\u8fd9\u90e8\u5206\u662f\u6574\u7bc7\u6587\u7ae0\u6700\u91cd\u8981\u7684\u5b9e\u6218\u5185\u5bb9\u3002\u6211\u5728\u524d\u8a00\u91cc\u63d0\u5230\u7684\u90a3\u6b21\u7ebf\u4e0a\u4e8b\u6545&#xff0c;\u5c31\u51fa\u5728\u8fd9\u91cc\u3002<\/p>\n<h4>5.1 JDK 1.7 \u7684\u6b7b\u5faa\u73af\u95ee\u9898<\/h4>\n<p>\u5148\u7528\u56fe\u6765\u7406\u89e3 JDK 1.7 \u6269\u5bb9\u65f6\u4e3a\u4ec0\u4e48\u4f1a\u6b7b\u5faa\u73af\u3002<\/p>\n<p>\u5047\u8bbe\u5f53\u524d\u94fe\u8868\u662f A -&gt; B -&gt; null&#xff0c;\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u89e6\u53d1\u6269\u5bb9&#xff1a;<\/p>\n<p>     \u5171\u4eab\u5185\u5b58<\/p>\n<p>     \u7ebf\u7a0b2<\/p>\n<p>     \u7ebf\u7a0b1<\/p>\n<p>      \u5171\u4eab\u5185\u5b58<\/p>\n<p>      \u7ebf\u7a0b2<\/p>\n<p>      \u7ebf\u7a0b1<\/p>\n<p>  #mermaid-svg-nGUteG2ROhgjZ83E{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-nGUteG2ROhgjZ83E .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-nGUteG2ROhgjZ83E .error-icon{fill:#552222;}#mermaid-svg-nGUteG2ROhgjZ83E .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-nGUteG2ROhgjZ83E .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-nGUteG2ROhgjZ83E .marker{fill:#333333;stroke:#333333;}#mermaid-svg-nGUteG2ROhgjZ83E .marker.cross{stroke:#333333;}#mermaid-svg-nGUteG2ROhgjZ83E svg{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-nGUteG2ROhgjZ83E p{margin:0;}#mermaid-svg-nGUteG2ROhgjZ83E .actor{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-nGUteG2ROhgjZ83E text.actor&gt;tspan{fill:black;stroke:none;}#mermaid-svg-nGUteG2ROhgjZ83E .actor-line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-nGUteG2ROhgjZ83E .innerArc{stroke-width:1.5;stroke-dasharray:none;}#mermaid-svg-nGUteG2ROhgjZ83E .messageLine0{stroke-width:1.5;stroke-dasharray:none;stroke:#333;}#mermaid-svg-nGUteG2ROhgjZ83E .messageLine1{stroke-width:1.5;stroke-dasharray:2,2;stroke:#333;}#mermaid-svg-nGUteG2ROhgjZ83E #arrowhead path{fill:#333;stroke:#333;}#mermaid-svg-nGUteG2ROhgjZ83E .sequenceNumber{fill:white;}#mermaid-svg-nGUteG2ROhgjZ83E #sequencenumber{fill:#333;}#mermaid-svg-nGUteG2ROhgjZ83E #crosshead path{fill:#333;stroke:#333;}#mermaid-svg-nGUteG2ROhgjZ83E .messageText{fill:#333;stroke:none;}#mermaid-svg-nGUteG2ROhgjZ83E .labelBox{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-nGUteG2ROhgjZ83E .labelText,#mermaid-svg-nGUteG2ROhgjZ83E .labelText&gt;tspan{fill:black;stroke:none;}#mermaid-svg-nGUteG2ROhgjZ83E .loopText,#mermaid-svg-nGUteG2ROhgjZ83E .loopText&gt;tspan{fill:black;stroke:none;}#mermaid-svg-nGUteG2ROhgjZ83E .loopLine{stroke-width:2px;stroke-dasharray:2,2;stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-nGUteG2ROhgjZ83E .note{stroke:#aaaa33;fill:#fff5ad;}#mermaid-svg-nGUteG2ROhgjZ83E .noteText,#mermaid-svg-nGUteG2ROhgjZ83E .noteText&gt;tspan{fill:black;stroke:none;}#mermaid-svg-nGUteG2ROhgjZ83E .activation0{fill:#f4f4f4;stroke:#666;}#mermaid-svg-nGUteG2ROhgjZ83E .activation1{fill:#f4f4f4;stroke:#666;}#mermaid-svg-nGUteG2ROhgjZ83E .activation2{fill:#f4f4f4;stroke:#666;}#mermaid-svg-nGUteG2ROhgjZ83E .actorPopupMenu{position:absolute;}#mermaid-svg-nGUteG2ROhgjZ83E .actorPopupMenuPanel{position:absolute;fill:#ECECFF;box-shadow:0px 8px 16px 0px rgba(0,0,0,0.2);filter:drop-shadow(3px 5px 2px rgb(0 0 0 \/ 0.4));}#mermaid-svg-nGUteG2ROhgjZ83E .actor-man line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-nGUteG2ROhgjZ83E .actor-man circle,#mermaid-svg-nGUteG2ROhgjZ83E line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;stroke-width:2px;}#mermaid-svg-nGUteG2ROhgjZ83E :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>     \u539f\u94fe\u8868: A -&gt;&gt; B -&gt;&gt; null<\/p>\n<p>     \u6269\u5bb9\u540e(\u5934\u63d2\u6cd5): B -&gt;&gt; A -&gt;&gt; null<\/p>\n<p>     \u26a0\ufe0f \u5f62\u6210\u73af: A -&gt;&gt; B -&gt;&gt; A -&gt;&gt; B&#8230;<\/p>\n<p>   \u8bfb\u53d6 e&#061;A, next&#061;B<\/p>\n<p>   \u7ebf\u7a0b1\u88ab\u6302\u8d77(\u65f6\u95f4\u7247\u7528\u5b8c)<\/p>\n<p>   \u5b8c\u6210\u6574\u4e2a\u6269\u5bb9\u8fc7\u7a0b<\/p>\n<p>   \u6062\u590d\u6267\u884c<\/p>\n<p>   \u5934\u63d2A\u5230\u65b0table: A -&gt;&gt; null<\/p>\n<p>   next&#061;B, \u7ee7\u7eed\u5904\u7406B<\/p>\n<p>   B.next &#061; A (\u56e0\u4e3a\u6269\u5bb9\u540eB.next\u6307\u5411A)<\/p>\n<p>   \u5934\u63d2B: B -&gt;&gt; A -&gt;&gt; null<\/p>\n<p>   next &#061; A (B.next\u5728\u6269\u5bb9\u524d\u662fA)<\/p>\n<p>   \u5904\u7406A: A.next\u5df2\u6307\u5411B<\/p>\n<p>\u6838\u5fc3\u539f\u56e0&#xff1a;\u5934\u63d2\u6cd5\u5728\u6269\u5bb9\u65f6\u4f1a\u53cd\u8f6c\u94fe\u8868\u987a\u5e8f&#xff0c;\u4e24\u4e2a\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c\u65f6&#xff0c;\u4f1a\u5f62\u6210\u4e00\u4e2a\u6307\u9488\u73af&#xff0c;\u5bfc\u81f4\u540e\u7eed\u7684 get \u64cd\u4f5c\u9677\u5165\u65e0\u9650\u5faa\u73af&#xff0c;CPU 100%\u3002<\/p>\n<h4>5.2 JDK 1.8 \u7684\u6539\u8fdb\u4e0e\u6b8b\u7559\u95ee\u9898<\/h4>\n<p>JDK 1.8 \u6539\u6210\u5c3e\u63d2\u6cd5\u4e4b\u540e&#xff0c;\u6269\u5bb9\u65f6\u4e0d\u518d\u53cd\u8f6c\u94fe\u8868&#xff0c;\u6240\u4ee5\u4e0d\u4f1a\u518d\u51fa\u73b0\u6b7b\u5faa\u73af\u3002\u4f46\u662f\u2014\u2014<\/p>\n<p>HashMap \u5728 JDK 1.8 \u4e2d\u4ecd\u7136\u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168\u7684&#xff01;\u591a\u7ebf\u7a0b\u5e76\u53d1 put \u65f6&#xff0c;\u53ef\u80fd\u4f1a\u51fa\u73b0\u6570\u636e\u4e22\u5931&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ \u8fd9\u662f\u4e00\u4e2a\u53cd\u9762\u6559\u6750&#xff01;\u5343\u4e07\u4e0d\u8981\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u8fd9\u6837\u7528&#xff01;<\/span><br \/>\n<span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> map <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u7ebf\u7a0b1\u548c\u7ebf\u7a0b2\u540c\u65f6\u6267\u884c put&#xff0c;\u4e14\u4e24\u4e2a key \u6620\u5c04\u5230\u540c\u4e00\u4e2a bucket<\/span><br \/>\n<span class=\"token comment\">\/\/ \u5f53\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u5224\u65ad (p.next &#061;&#061; null) \u4e3a true<\/span><br \/>\n<span class=\"token comment\">\/\/ \u90fd\u6267\u884c p.next &#061; newNode(&#8230;)<\/span><br \/>\n<span class=\"token comment\">\/\/ \u5176\u4e2d\u4e00\u4e2a\u7ebf\u7a0b\u7684\u5199\u5165\u4f1a\u88ab\u8986\u76d6&#xff0c;\u6570\u636e\u76f4\u63a5\u4e22\u5931&#xff01;<\/span><\/p>\n<p>\u53e6\u5916&#xff0c;JDK 1.8 \u7684\u6269\u5bb9\u8fc7\u7a0b\u4e2d&#xff0c;\u591a\u7ebf\u7a0b\u53ef\u80fd\u5bfc\u81f4 table \u5f15\u7528\u548c size \u4e0d\u4e00\u81f4&#xff0c;\u6700\u7ec8\u4e5f\u4f1a\u51fa\u73b0\u5404\u79cd\u7a00\u5947\u53e4\u602a\u7684\u95ee\u9898&#xff0c;\u6bd4\u5982 get \u8fd4\u56de null&#xff08;\u660e\u660e\u5df2\u7ecf put \u8fc7\u4e86&#xff09;\u3002<\/p>\n<h4>5.3 \u6b63\u786e\u7684\u591a\u7ebf\u7a0b\u65b9\u6848<\/h4>\n<p>\u8001\u5b9e\u8bf4&#xff0c;\u5de5\u4f5c\u8fd9\u4e48\u591a\u5e74&#xff0c;\u6211\u89c1\u8fc7\u592a\u591a\u628a HashMap \u7528\u5728\u591a\u7ebf\u7a0b\u573a\u666f\u7684\u4ee3\u7801\u4e86\u3002\u8fd9\u91cc\u7ed9\u51fa\u51e0\u4e2a\u6b63\u786e\u59ff\u52bf&#xff1a;<\/p>\n<p>\u65b9\u6848\u4e00&#xff1a;\u4f7f\u7528 ConcurrentHashMap&#xff08;\u63a8\u8350&#xff09;<\/p>\n<p><span class=\"token keyword\">import<\/span> <span class=\"token import\"><span class=\"token namespace\">java<span class=\"token punctuation\">.<\/span>util<span class=\"token punctuation\">.<\/span>concurrent<span class=\"token punctuation\">.<\/span><\/span><span class=\"token class-name\">ConcurrentHashMap<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u76f4\u63a5\u66ff\u6362&#xff0c;API \u57fa\u672c\u4e00\u81f4<\/span><br \/>\n<span class=\"token class-name\">ConcurrentHashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> map <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ConcurrentHashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ JDK 1.7: \u5206\u6bb5\u9501&#xff08;Segment&#xff09;<\/span><br \/>\n<span class=\"token comment\">\/\/ JDK 1.8: CAS &#043; synchronized&#xff0c;\u9501\u7684\u7c92\u5ea6\u66f4\u7ec6&#xff08;\u53ea\u9501\u94fe\u8868\/\u6811\u7684\u5934\u8282\u70b9&#xff09;<\/span><br \/>\nmap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;user_count&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">100<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token class-name\">Integer<\/span> count <span class=\"token operator\">&#061;<\/span> map<span class=\"token punctuation\">.<\/span><span class=\"token function\">get<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;user_count&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u539f\u5b50\u64cd\u4f5c&#xff1a;\u4e0d\u5b58\u5728\u624d\u63d2\u5165<\/span><br \/>\nmap<span class=\"token punctuation\">.<\/span><span class=\"token function\">putIfAbsent<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;session_id&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u539f\u5b50\u64cd\u4f5c&#xff1a;\u8ba1\u7b97\u5e76\u66f4\u65b0<\/span><br \/>\nmap<span class=\"token punctuation\">.<\/span><span class=\"token function\">compute<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;visit_count&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span>key<span class=\"token punctuation\">,<\/span> oldVal<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">-&gt;<\/span> oldVal <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">?<\/span> <span class=\"token number\">1<\/span> <span class=\"token operator\">:<\/span> oldVal <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>\u65b9\u6848\u4e8c&#xff1a;Collections.synchronizedMap&#xff08;\u4e0d\u63a8\u8350&#xff0c;\u6027\u80fd\u5dee&#xff09;<\/p>\n<p><span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> syncMap <span class=\"token operator\">&#061;<\/span> <span class=\"token class-name\">Collections<\/span><span class=\"token punctuation\">.<\/span><span class=\"token function\">synchronizedMap<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u6240\u6709\u64cd\u4f5c\u90fd\u52a0\u4e86 synchronized&#xff0c;\u5e76\u53d1\u6027\u80fd\u5f88\u5dee<\/span><br \/>\n<span class=\"token comment\">\/\/ \u800c\u4e14\u904d\u5386\u7684\u65f6\u5019\u8fd8\u9700\u8981\u624b\u52a8\u52a0\u9501&#xff0c;\u5426\u5219\u4f9d\u7136\u4e0d\u5b89\u5168<\/span><br \/>\n<span class=\"token keyword\">synchronized<\/span> <span class=\"token punctuation\">(<\/span>syncMap<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Map<span class=\"token punctuation\">.<\/span>Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> entry <span class=\"token operator\">:<\/span> syncMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">entrySet<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u904d\u5386\u903b\u8f91<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u65b9\u6848\u4e09&#xff1a;Hashtable&#xff08;\u522b\u7528\u4e86&#xff0c;\u592a\u8001\u4e86&#xff09;<\/p>\n<p><span class=\"token comment\">\/\/ Hashtable \u7684\u6240\u6709\u65b9\u6cd5\u90fd\u52a0\u4e86 synchronized<\/span><br \/>\n<span class=\"token comment\">\/\/ \u6027\u80fd\u6bd4 Collections.synchronizedMap \u8fd8\u5dee<\/span><br \/>\n<span class=\"token comment\">\/\/ \u800c\u4e14\u7ee7\u627f\u4e86\u5f88\u591a\u5386\u53f2\u9057\u7559\u95ee\u9898&#xff0c;\u73b0\u4ee3\u9879\u76ee\u522b\u7528\u8fd9\u4e2a\u4e86<\/span><br \/>\n<span class=\"token class-name\">Hashtable<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> table <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Hashtable<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>\u7ed3\u8bba&#xff1a;\u591a\u7ebf\u7a0b\u573a\u666f&#xff0c;\u8001\u8001\u5b9e\u5b9e\u7528 ConcurrentHashMap\u3002<\/p>\n<h3>\u516d\u3001\u7ea2\u9ed1\u6811\u7684\u90a3\u4e9b\u7ec6\u8282<\/h3>\n<p>\u7ea2\u9ed1\u6811\u8fd9\u5757\u5f88\u591a\u6587\u7ae0\u4e00\u7b14\u5e26\u8fc7&#xff0c;\u4f46\u5982\u679c\u9762\u8bd5\u88ab\u95ee\u5230&#034;\u4e3a\u4ec0\u4e48\u7528\u7ea2\u9ed1\u6811\u800c\u4e0d\u7528 AVL \u6811&#034;&#xff0c;\u4e0d\u63d0\u524d\u60f3\u6e05\u695a\u53ef\u80fd\u4f1a\u7b54\u9519\u3002<\/p>\n<h4>6.1 \u7ea2\u9ed1\u6811 vs AVL \u6811<\/h4>\n<p>AVL \u6811\u662f\u4e25\u683c\u5e73\u8861\u7684\u4e8c\u53c9\u641c\u7d22\u6811&#xff0c;\u5de6\u53f3\u5b50\u6811\u9ad8\u5ea6\u5dee\u4e0d\u8d85\u8fc7 1&#xff0c;\u67e5\u627e\u6548\u7387\u6781\u9ad8&#xff0c;\u4f46\u7ef4\u62a4\u5e73\u8861\u7684\u4ee3\u4ef7\u4e5f\u5927\u2014\u2014\u6bcf\u6b21\u63d2\u5165\u5220\u9664\u90fd\u53ef\u80fd\u89e6\u53d1\u5927\u91cf\u65cb\u8f6c\u64cd\u4f5c\u3002<\/p>\n<p>\u7ea2\u9ed1\u6811\u662f&#034;\u8fd1\u4f3c\u5e73\u8861&#034;\u7684&#xff0c;\u4e0d\u8981\u6c42\u4e25\u683c\u5e73\u8861&#xff0c;\u63d2\u5165\u548c\u5220\u9664\u65f6\u65cb\u8f6c\u6b21\u6570\u66f4\u5c11&#xff08;\u6700\u591a 3 \u6b21\u65cb\u8f6c&#xff09;\u3002\u5bf9\u4e8e HashMap \u8fd9\u79cd\u8bfb\u5199\u90fd\u9891\u7e41\u7684\u573a\u666f&#xff0c;\u7ea2\u9ed1\u6811\u7684\u7efc\u5408\u6027\u80fd\u66f4\u4f18\u3002<\/p>\n<p>  #mermaid-svg-vIoAJVH08MpGtjho{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-vIoAJVH08MpGtjho .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-vIoAJVH08MpGtjho .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-vIoAJVH08MpGtjho .error-icon{fill:#552222;}#mermaid-svg-vIoAJVH08MpGtjho .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-vIoAJVH08MpGtjho .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-vIoAJVH08MpGtjho .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-vIoAJVH08MpGtjho .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-vIoAJVH08MpGtjho .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-vIoAJVH08MpGtjho .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-vIoAJVH08MpGtjho .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-vIoAJVH08MpGtjho .marker{fill:#333333;stroke:#333333;}#mermaid-svg-vIoAJVH08MpGtjho .marker.cross{stroke:#333333;}#mermaid-svg-vIoAJVH08MpGtjho svg{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-vIoAJVH08MpGtjho p{margin:0;}#mermaid-svg-vIoAJVH08MpGtjho .label{font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;color:#333;}#mermaid-svg-vIoAJVH08MpGtjho .cluster-label text{fill:#333;}#mermaid-svg-vIoAJVH08MpGtjho .cluster-label span{color:#333;}#mermaid-svg-vIoAJVH08MpGtjho .cluster-label span p{background-color:transparent;}#mermaid-svg-vIoAJVH08MpGtjho .label text,#mermaid-svg-vIoAJVH08MpGtjho span{fill:#333;color:#333;}#mermaid-svg-vIoAJVH08MpGtjho .node rect,#mermaid-svg-vIoAJVH08MpGtjho .node circle,#mermaid-svg-vIoAJVH08MpGtjho .node ellipse,#mermaid-svg-vIoAJVH08MpGtjho .node polygon,#mermaid-svg-vIoAJVH08MpGtjho .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-vIoAJVH08MpGtjho .rough-node .label text,#mermaid-svg-vIoAJVH08MpGtjho .node .label text,#mermaid-svg-vIoAJVH08MpGtjho .image-shape .label,#mermaid-svg-vIoAJVH08MpGtjho .icon-shape .label{text-anchor:middle;}#mermaid-svg-vIoAJVH08MpGtjho .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-vIoAJVH08MpGtjho .rough-node .label,#mermaid-svg-vIoAJVH08MpGtjho .node .label,#mermaid-svg-vIoAJVH08MpGtjho .image-shape .label,#mermaid-svg-vIoAJVH08MpGtjho .icon-shape .label{text-align:center;}#mermaid-svg-vIoAJVH08MpGtjho .node.clickable{cursor:pointer;}#mermaid-svg-vIoAJVH08MpGtjho .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-vIoAJVH08MpGtjho .arrowheadPath{fill:#333333;}#mermaid-svg-vIoAJVH08MpGtjho .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-vIoAJVH08MpGtjho .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-vIoAJVH08MpGtjho .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-vIoAJVH08MpGtjho .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-vIoAJVH08MpGtjho .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-vIoAJVH08MpGtjho .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-vIoAJVH08MpGtjho .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-vIoAJVH08MpGtjho .cluster text{fill:#333;}#mermaid-svg-vIoAJVH08MpGtjho .cluster span{color:#333;}#mermaid-svg-vIoAJVH08MpGtjho div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-vIoAJVH08MpGtjho .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-vIoAJVH08MpGtjho rect.text{fill:none;stroke-width:0;}#mermaid-svg-vIoAJVH08MpGtjho .icon-shape,#mermaid-svg-vIoAJVH08MpGtjho .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-vIoAJVH08MpGtjho .icon-shape p,#mermaid-svg-vIoAJVH08MpGtjho .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-vIoAJVH08MpGtjho .icon-shape .label rect,#mermaid-svg-vIoAJVH08MpGtjho .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-vIoAJVH08MpGtjho .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-vIoAJVH08MpGtjho .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-vIoAJVH08MpGtjho :root{&#8211;mermaid-font-family:\\&#8221;trebuchet ms\\&#8221;,verdana,arial,sans-serif;}<\/p>\n<p>           <span class=\"nodeLabel\"><\/p>\n<p>\u7ea2\u9ed1\u6811\u793a\u4f8b (HashMap\u5185\u7684 bucket)<\/p>\n<p><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span class=\"edgeLabel\"><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u9ed1\u8282\u70b9: 7<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u7ea2\u8282\u70b9: 3<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u9ed1\u8282\u70b9: 11<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u9ed1\u8282\u70b9: 1<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u9ed1\u8282\u70b9: 5<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u7ea2\u8282\u70b9: 9<\/p>\n<p><\/span><\/p>\n<p>           <span style=\"color:#fff !important\" class=\"nodeLabel\"><\/p>\n<p>\u7ea2\u8282\u70b9: 13<\/p>\n<p><\/span><\/p>\n<h4>6.2 \u6811\u5316\u4e0e\u53cd\u6811\u5316\u9608\u503c\u4e3a\u4ec0\u4e48\u662f 8 \u548c 6&#xff1f;<\/h4>\n<ul>\n<li>\u6811\u5316\u9608\u503c 8&#xff1a;\u6cca\u677e\u5206\u5e03\u8ba1\u7b97\u7684\u7ed3\u679c&#xff0c;\u6b63\u5e38\u60c5\u51b5\u4e0b\u94fe\u8868\u957f\u5ea6\u8d85\u8fc7 8 \u7684\u6982\u7387\u6781\u4f4e&#xff08;\u7ea6 6\u00d710\u207b\u2078&#xff09;&#xff0c;\u53ea\u6709\u54c8\u5e0c\u51fd\u6570\u5f88\u5dee\u6216\u8005\u6570\u636e\u523b\u610f\u6784\u9020\u7684\u65f6\u5019\u624d\u4f1a\u53d1\u751f\u3002<\/li>\n<li>\u53cd\u6811\u5316\u9608\u503c 6&#xff1a;\u5e76\u4e0d\u662f 7&#xff0c;\u800c\u662f 6&#xff0c;\u4e3a\u4e86\u9632\u6b62\u9891\u7e41\u5728\u94fe\u8868\u548c\u7ea2\u9ed1\u6811\u4e4b\u95f4\u6765\u56de\u8f6c\u6362\u2014\u2014\u5982\u679c\u6811\u5316\u548c\u53cd\u6811\u5316\u7684\u9608\u503c\u4e00\u6837&#xff0c;\u6bd4\u5982\u90fd\u662f 8&#xff0c;\u90a3\u4e48\u5220\u9664\u4e00\u4e2a\u5143\u7d20\u53d8\u6210 7 \u5c31\u9000\u5316\u6210\u94fe\u8868&#xff0c;\u518d\u63d2\u5165\u4e00\u4e2a\u53d8\u6210 8 \u53c8\u6811\u5316&#xff0c;\u8fd9\u5c31\u662f\u6027\u80fd\u6296\u52a8&#xff0c;\u5f88\u8822\u3002\u8bbe\u7f6e\u4e00\u4e2a\u5dee\u503c&#xff08;8 &#8211; 6 &#061; 2&#xff09;\u6765\u505a\u7f13\u51b2&#xff0c;\u662f\u5f88\u5408\u7406\u7684\u8bbe\u8ba1\u3002<\/li>\n<\/ul>\n<p><span class=\"token comment\">\/\/ JDK 1.8 \u4e2d\u76f8\u5173\u7684\u5e38\u91cf\u5b9a\u4e49<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token constant\">TREEIFY_THRESHOLD<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">8<\/span><span class=\"token punctuation\">;<\/span>    <span class=\"token comment\">\/\/ \u6811\u5316\u9608\u503c<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token constant\">UNTREEIFY_THRESHOLD<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">6<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u53cd\u6811\u5316\u9608\u503c<\/span><br \/>\n<span class=\"token keyword\">static<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token constant\">MIN_TREEIFY_CAPACITY<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">64<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u6700\u5c0f\u6811\u5316\u6570\u7ec4\u5bb9\u91cf<\/span><\/p>\n<p>\u6ce8\u610f MIN_TREEIFY_CAPACITY &#061; 64 \u8fd9\u4e2a\u5e38\u91cf\u2014\u2014\u5982\u679c\u6570\u7ec4\u957f\u5ea6\u8fd8\u4e0d\u5230 64&#xff0c;\u5373\u4f7f\u94fe\u8868\u957f\u5ea6\u8d85\u8fc7 8&#xff0c;\u4e5f\u4e0d\u4f1a\u6811\u5316&#xff0c;\u800c\u662f\u9009\u62e9\u6269\u5bb9\u3002\u8fd9\u662f\u56e0\u4e3a\u5f53\u6570\u7ec4\u957f\u5ea6\u6bd4\u8f83\u5c0f\u7684\u65f6\u5019&#xff0c;\u6269\u5bb9\u53ef\u4ee5\u66f4\u6709\u6548\u5730\u51cf\u5c11\u54c8\u5e0c\u51b2\u7a81&#xff0c;\u6ca1\u5fc5\u8981\u6025\u7740\u6811\u5316\u3002<\/p>\n<h3>\u4e03\u3001\u4ece\u5b9e\u6218\u89d2\u5ea6&#xff1a;\u5982\u4f55\u7528\u597d HashMap&#xff1f;<\/h3>\n<p>\u5149\u77e5\u9053\u539f\u7406\u8fd8\u4e0d\u591f&#xff0c;\u5de5\u7a0b\u4e0a\u600e\u4e48\u7528\u624d\u662f\u5173\u952e\u3002<\/p>\n<h4>7.1 \u521d\u59cb\u5316\u5bb9\u91cf\u7684\u8bbe\u7f6e<\/h4>\n<p>\u8fd9\u4e2a\u7ec6\u8282\u5f88\u591a\u4eba\u5ffd\u7565&#xff0c;\u4f46\u53ef\u80fd\u5bf9\u6027\u80fd\u6709\u5f71\u54cd\u3002<\/p>\n<p>\u5982\u679c\u4f60\u5df2\u7ecf\u77e5\u9053 HashMap \u91cc\u5927\u6982\u4f1a\u653e\u591a\u5c11\u5143\u7d20&#xff0c;\u5e94\u8be5\u5728\u521d\u59cb\u5316\u7684\u65f6\u5019\u5c31\u6307\u5b9a\u5bb9\u91cf&#xff0c;\u907f\u514d\u9891\u7e41\u6269\u5bb9&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ \u53cd\u9762\u6559\u6750&#xff1a;\u4e0d\u6307\u5b9a\u521d\u59cb\u5bb9\u91cf<\/span><br \/>\n<span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> userInfo <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u968f\u7740\u6570\u636e\u589e\u52a0&#xff0c;\u4f1a\u89e6\u53d1\u591a\u6b21\u6269\u5bb9&#xff08;\u6bcf\u6b21\u6269\u5bb9\u90fd\u8981 rehash&#xff0c;\u6027\u80fd\u5f00\u9500\u5927&#xff09;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u6b63\u786e\u505a\u6cd5&#xff1a;\u9884\u4f30\u597d\u6570\u91cf&#xff0c;\u9664\u4ee5\u8d1f\u8f7d\u56e0\u5b50&#xff0c;\u5411\u4e0a\u53d6\u6574\u5230 2 \u7684\u5e42<\/span><br \/>\n<span class=\"token comment\">\/\/ \u6bd4\u5982\u9884\u8ba1\u5b58 100 \u4e2a\u5143\u7d20&#xff1a;100 \/ 0.75 &#061; 134&#xff0c;\u6240\u4ee5\u521d\u59cb\u5316 256&#xff08;2^8&#xff09;<\/span><br \/>\n<span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Object<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> userInfoOptimized <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">256<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u6216\u8005\u7528 Guava \u63d0\u4f9b\u7684\u5de5\u5177\u65b9\u6cd5&#xff0c;\u5b83\u5e2e\u4f60\u7b97\u597d\u4e86<\/span><br \/>\n<span class=\"token comment\">\/\/ Maps.newHashMapWithExpectedSize(100)<\/span><br \/>\n<span class=\"token comment\">\/\/ \u7b49\u4ef7\u4e8e new HashMap&lt;&gt;(147)&#xff0c;\u5185\u90e8\u6309 expectedSize \/ 0.75 &#043; 1 \u8ba1\u7b97<\/span><\/p>\n<h4>7.2 Key \u7684\u8bbe\u8ba1\u539f\u5219<\/h4>\n<p>HashMap \u7684 key \u9700\u8981\u6b63\u786e\u5b9e\u73b0 hashCode() \u548c equals() \u65b9\u6cd5&#xff0c;\u8fd9\u51e0\u4e4e\u662f\u4e2a\u8001\u751f\u5e38\u8c08\u7684\u70b9&#xff0c;\u4f46\u8e29\u5751\u7684\u4eba\u4f9d\u7136\u4e0d\u5c11&#xff1a;<\/p>\n<p><span class=\"token comment\">\/\/ \u53cd\u9762\u6559\u6750&#xff1a;\u7528\u53ef\u53d8\u5bf9\u8c61\u4f5c\u4e3a key<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">MutableKey<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token class-name\">String<\/span> name<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token comment\">\/\/ \u7701\u7565 hashCode \u548c equals&#xff0c;\u90fd\u57fa\u4e8e name<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">MutableKey<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> map <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token class-name\">MutableKey<\/span> key <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">MutableKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;Alice&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\nmap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span>key<span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;\u5de5\u7a0b\u5e08&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>key<span class=\"token punctuation\">.<\/span><span class=\"token function\">setName<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;Bob&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u4fee\u6539\u4e86 key \u7684\u5c5e\u6027&#xff01;<\/span><br \/>\n<span class=\"token comment\">\/\/ \u6b64\u65f6 key \u7684 hashCode \u53d8\u4e86&#xff0c;\u4f46\u5b83\u5728 map \u91cc\u5b58\u7684\u4f4d\u7f6e\u6ca1\u53d8<\/span><br \/>\n<span class=\"token comment\">\/\/ get \u64cd\u4f5c\u7528\u65b0\u7684 hashCode \u627e&#xff0c;\u627e\u5230\u9519\u8bef\u7684 bucket&#xff0c;\u8fd4\u56de null<\/span><br \/>\n<span class=\"token class-name\">String<\/span> value <span class=\"token operator\">&#061;<\/span> map<span class=\"token punctuation\">.<\/span><span class=\"token function\">get<\/span><span class=\"token punctuation\">(<\/span>key<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ null&#xff01;&#xff01;&#xff01;<\/span><br \/>\n<span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span>value<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>    <span class=\"token comment\">\/\/ \u6570\u636e&#034;\u4e22\u5931&#034;\u4e86&#xff0c;\u5176\u5b9e\u8fd8\u5728&#xff0c;\u53ea\u662f\u627e\u4e0d\u5230\u4e86<\/span><\/p>\n<p>\u6700\u4f73\u5b9e\u8df5&#xff1a;\u7528\u4e0d\u53ef\u53d8\u5bf9\u8c61\u4f5c\u4e3a key&#xff0c;\u6bd4\u5982 String\u3001Integer \u7b49\u5305\u88c5\u7c7b&#xff0c;\u6216\u8005\u4f60\u81ea\u5df1\u5b9a\u4e49\u7684 final \u7c7b\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u6b63\u786e\u505a\u6cd5&#xff1a;\u7528\u4e0d\u53ef\u53d8\u7684 String \u4f5c\u4e3a key<\/span><br \/>\n<span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">UserInfo<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> userMap <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\nuserMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;user_001&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">UserInfo<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;Alice&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">28<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token comment\">\/\/ String \u662f\u4e0d\u53ef\u53d8\u7684&#xff0c;hashCode \u4e0d\u4f1a\u53d8&#xff0c;\u5b89\u5168<\/span><\/p>\n<h4>7.3 \u4e00\u4e2a\u5b8c\u6574\u7684\u7535\u5546\u573a\u666f\u793a\u4f8b<\/h4>\n<p>\u7ed3\u5408\u4e00\u4e2a\u771f\u5b9e\u573a\u666f\u6765\u5c55\u793a HashMap \u7684\u5408\u7406\u7528\u6cd5\u2014\u2014\u4e00\u4e2a\u7b80\u5355\u7684\u5546\u54c1\u5e93\u5b58\u7ba1\u7406\u6a21\u5757&#xff1a;<\/p>\n<p><span class=\"token keyword\">import<\/span> <span class=\"token import\"><span class=\"token namespace\">java<span class=\"token punctuation\">.<\/span>util<span class=\"token punctuation\">.<\/span><\/span><span class=\"token class-name\">HashMap<\/span><\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token keyword\">import<\/span> <span class=\"token import\"><span class=\"token namespace\">java<span class=\"token punctuation\">.<\/span>util<span class=\"token punctuation\">.<\/span><\/span><span class=\"token class-name\">Map<\/span><\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token keyword\">import<\/span> <span class=\"token import\"><span class=\"token namespace\">java<span class=\"token punctuation\">.<\/span>util<span class=\"token punctuation\">.<\/span>concurrent<span class=\"token punctuation\">.<\/span><\/span><span class=\"token class-name\">ConcurrentHashMap<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/**<br \/>\n * \u5546\u54c1\u5e93\u5b58\u7ba1\u7406\u670d\u52a1<br \/>\n * \u5355\u673a\u7248\u7528 HashMap&#xff0c;\u5206\u5e03\u5f0f\u573a\u666f\u9700\u8981\u6362\u6210 Redis<br \/>\n *\/<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">InventoryService<\/span> <span class=\"token punctuation\">{<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ \u5355\u7ebf\u7a0b\u64cd\u4f5c\u7528 HashMap&#xff08;\u6bd4\u5982\u6279\u91cf\u5bfc\u5165\u573a\u666f&#xff09;<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> localCache<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ \u591a\u7ebf\u7a0b\u64cd\u4f5c\u7528 ConcurrentHashMap&#xff08;\u6bd4\u5982\u5e76\u53d1\u4e0b\u5355\u573a\u666f&#xff09;<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token keyword\">final<\/span> <span class=\"token class-name\">ConcurrentHashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> stockMap<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token keyword\">public<\/span> <span class=\"token class-name\">InventoryService<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> expectedProductCount<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u9884\u4f30\u5546\u54c1\u6570\u91cf&#xff0c;\u8ba1\u7b97\u5408\u7406\u7684\u521d\u59cb\u5bb9\u91cf&#xff0c;\u907f\u514d\u6269\u5bb9\u5f00\u9500<\/span><br \/>\n        <span class=\"token comment\">\/\/ expectedProductCount \/ 0.75 &#043; 1&#xff0c;\u53d6\u6700\u8fd1\u7684 2 \u7684\u5e42<\/span><br \/>\n        <span class=\"token keyword\">int<\/span> initialCapacity <span class=\"token operator\">&#061;<\/span> <span class=\"token function\">tableSizeFor<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">(<\/span>expectedProductCount <span class=\"token operator\">\/<\/span> <span class=\"token number\">0.75f<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1.0f<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token keyword\">this<\/span><span class=\"token punctuation\">.<\/span>localCache <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span>initialCapacity<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">this<\/span><span class=\"token punctuation\">.<\/span>stockMap <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ConcurrentHashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span>initialCapacity<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/**<br \/>\n     * \u6279\u91cf\u521d\u59cb\u5316\u5e93\u5b58&#xff08;\u5355\u7ebf\u7a0b\u6279\u91cf\u5bfc\u5165&#xff0c;\u7528\u666e\u901a HashMap \u5904\u7406\u540e\u8f6c\u5165&#xff09;<br \/>\n     *\/<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">batchInitStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> stockData<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u5728\u5355\u7ebf\u7a0b\u7684\u6279\u91cf\u5904\u7406\u903b\u8f91\u91cc\u7528 HashMap \u4e34\u65f6\u5b58\u50a8&#xff0c;\u6027\u80fd\u66f4\u597d<\/span><br \/>\n        <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> tempMap <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span>stockData<span class=\"token punctuation\">.<\/span><span class=\"token function\">size<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">*<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Map<span class=\"token punctuation\">.<\/span>Entry<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> entry <span class=\"token operator\">:<\/span> stockData<span class=\"token punctuation\">.<\/span><span class=\"token function\">entrySet<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token class-name\">String<\/span> skuId <span class=\"token operator\">&#061;<\/span> entry<span class=\"token punctuation\">.<\/span><span class=\"token function\">getKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token class-name\">Integer<\/span> stock <span class=\"token operator\">&#061;<\/span> entry<span class=\"token punctuation\">.<\/span><span class=\"token function\">getValue<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>            <span class=\"token comment\">\/\/ \u7b80\u5355\u7684\u6570\u636e\u6821\u9a8c<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>skuId <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">||<\/span> skuId<span class=\"token punctuation\">.<\/span><span class=\"token function\">isBlank<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">||<\/span> stock <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">||<\/span> stock <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n                <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>err<span class=\"token punctuation\">.<\/span><span class=\"token function\">printf<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u975e\u6cd5\u5e93\u5b58\u6570\u636e&#xff0c;\u8df3\u8fc7&#xff1a;skuId&#061;%s, stock&#061;%s%n&#034;<\/span><span class=\"token punctuation\">,<\/span> skuId<span class=\"token punctuation\">,<\/span> stock<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n                <span class=\"token keyword\">continue<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token punctuation\">}<\/span><\/p>\n<p>            tempMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span>skuId<span class=\"token punctuation\">,<\/span> stock<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u6279\u91cf\u8f6c\u5165\u7ebf\u7a0b\u5b89\u5168\u7684 ConcurrentHashMap<\/span><br \/>\n        stockMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">putAll<\/span><span class=\"token punctuation\">(<\/span>tempMap<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">printf<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u6210\u529f\u521d\u59cb\u5316 %d \u4e2a SKU \u7684\u5e93\u5b58\u6570\u636e%n&#034;<\/span><span class=\"token punctuation\">,<\/span> tempMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">size<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/**<br \/>\n     * \u6263\u51cf\u5e93\u5b58&#xff08;\u591a\u7ebf\u7a0b\u5b89\u5168\u7248&#xff09;<br \/>\n     * \u4f7f\u7528 ConcurrentHashMap \u7684\u539f\u5b50\u64cd\u4f5c<br \/>\n     *\/<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">boolean<\/span> <span class=\"token function\">deductStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> skuId<span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">int<\/span> quantity<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>skuId <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">||<\/span> quantity <span class=\"token operator\">&lt;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token keyword\">throw<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">IllegalArgumentException<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u53c2\u6570\u975e\u6cd5&#xff1a;skuId&#061;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> skuId <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034;, quantity&#061;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> quantity<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ compute \u65b9\u6cd5\u662f\u539f\u5b50\u64cd\u4f5c&#xff0c;\u907f\u514d\u5e76\u53d1\u6263\u51cf\u51fa\u73b0\u8d85\u5356<\/span><br \/>\n        <span class=\"token keyword\">final<\/span> <span class=\"token keyword\">int<\/span><span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span> result <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">{<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">}<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7528\u6570\u7ec4\u7ed5\u8fc7 lambda \u7684 effectively final \u9650\u5236<\/span><\/p>\n<p>        stockMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">compute<\/span><span class=\"token punctuation\">(<\/span>skuId<span class=\"token punctuation\">,<\/span> <span class=\"token punctuation\">(<\/span>key<span class=\"token punctuation\">,<\/span> currentStock<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">-&gt;<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>currentStock <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n                result<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token operator\">&#8211;<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u5546\u54c1\u4e0d\u5b58\u5728<\/span><br \/>\n                <span class=\"token keyword\">return<\/span> <span class=\"token keyword\">null<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token punctuation\">}<\/span><br \/>\n            <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>currentStock <span class=\"token operator\">&lt;<\/span> quantity<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n                result<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u5e93\u5b58\u4e0d\u8db3<\/span><br \/>\n                <span class=\"token keyword\">return<\/span> currentStock<span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u4e0d\u53d8<\/span><br \/>\n            <span class=\"token punctuation\">}<\/span><br \/>\n            result<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span>      <span class=\"token comment\">\/\/ \u6263\u51cf\u6210\u529f<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> currentStock <span class=\"token operator\">&#8211;<\/span> quantity<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>result<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">printf<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5e93\u5b58\u6263\u51cf\u6210\u529f&#xff1a;skuId&#061;%s, \u6263\u51cf\u6570\u91cf&#061;%d%n&#034;<\/span><span class=\"token punctuation\">,<\/span> skuId<span class=\"token punctuation\">,<\/span> quantity<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> <span class=\"token boolean\">true<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">else<\/span> <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>result<span class=\"token punctuation\">[<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">]<\/span> <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">printf<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5e93\u5b58\u4e0d\u8db3&#xff1a;skuId&#061;%s%n&#034;<\/span><span class=\"token punctuation\">,<\/span> skuId<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> <span class=\"token boolean\">false<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span> <span class=\"token keyword\">else<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">printf<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5546\u54c1\u4e0d\u5b58\u5728&#xff1a;skuId&#061;%s%n&#034;<\/span><span class=\"token punctuation\">,<\/span> skuId<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> <span class=\"token boolean\">false<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/**<br \/>\n     * \u67e5\u8be2\u5e93\u5b58<br \/>\n     *\/<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">getStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> skuId<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> stockMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">getOrDefault<\/span><span class=\"token punctuation\">(<\/span>skuId<span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/**<br \/>\n     * \u6279\u91cf\u67e5\u8be2\u5e93\u5b58&#xff08;\u8fd4\u56de\u4e00\u4e2a\u5feb\u7167&#xff0c;\u7528 HashMap \u5b58\u7ed3\u679c&#xff09;<br \/>\n     *\/<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> <span class=\"token function\">batchGetStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Iterable<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> skuIds<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> result <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> skuId <span class=\"token operator\">:<\/span> skuIds<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            result<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span>skuId<span class=\"token punctuation\">,<\/span> <span class=\"token function\">getStock<\/span><span class=\"token punctuation\">(<\/span>skuId<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> result<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token comment\">\/\/ \u8ba1\u7b97\u6700\u8fd1\u7684 2 \u7684\u5e42&#xff08;\u53c2\u8003 HashMap \u5185\u90e8\u5b9e\u73b0&#xff09;<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token keyword\">static<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">tableSizeFor<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">int<\/span> cap<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">int<\/span> n <span class=\"token operator\">&#061;<\/span> cap <span class=\"token operator\">&#8211;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">|&#061;<\/span> n <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">|&#061;<\/span> n <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">|&#061;<\/span> n <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">4<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">|&#061;<\/span> n <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">8<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        n <span class=\"token operator\">|&#061;<\/span> n <span class=\"token operator\">&gt;&gt;&gt;<\/span> <span class=\"token number\">16<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">?<\/span> <span class=\"token number\">1<\/span> <span class=\"token operator\">:<\/span> <span class=\"token punctuation\">(<\/span>n <span class=\"token operator\">&gt;&#061;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">1<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token number\">30<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">?<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">1<\/span> <span class=\"token operator\">&lt;&lt;<\/span> <span class=\"token number\">30<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">:<\/span> n <span class=\"token operator\">&#043;<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u4f7f\u7528\u793a\u4f8b<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">Main<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">static<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">main<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">[<\/span><span class=\"token punctuation\">]<\/span> args<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token class-name\">InventoryService<\/span> service <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">InventoryService<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">1000<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u6279\u91cf\u521d\u59cb\u5316<\/span><br \/>\n        <span class=\"token class-name\">Map<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> initData <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">HashMap<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token punctuation\">&gt;<\/span><\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        initData<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_APPLE_001&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">500<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        initData<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_MILK_002&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1000<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        initData<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_BREAD_003&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">300<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        service<span class=\"token punctuation\">.<\/span><span class=\"token function\">batchInitStock<\/span><span class=\"token punctuation\">(<\/span>initData<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u67e5\u8be2\u5e93\u5b58<\/span><br \/>\n        <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u82f9\u679c\u5e93\u5b58: &#034;<\/span> <span class=\"token operator\">&#043;<\/span> service<span class=\"token punctuation\">.<\/span><span class=\"token function\">getStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_APPLE_001&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ 500<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u6263\u51cf\u5e93\u5b58<\/span><br \/>\n        <span class=\"token keyword\">boolean<\/span> success <span class=\"token operator\">&#061;<\/span> service<span class=\"token punctuation\">.<\/span><span class=\"token function\">deductStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_APPLE_001&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">50<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u6263\u51cf\u7ed3\u679c: &#034;<\/span> <span class=\"token operator\">&#043;<\/span> success<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ true<\/span><br \/>\n        <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u6263\u51cf\u540e\u5e93\u5b58: &#034;<\/span> <span class=\"token operator\">&#043;<\/span> service<span class=\"token punctuation\">.<\/span><span class=\"token function\">getStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_APPLE_001&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ 450<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u5c1d\u8bd5\u8d85\u5356<\/span><br \/>\n        <span class=\"token keyword\">boolean<\/span> oversell <span class=\"token operator\">&#061;<\/span> service<span class=\"token punctuation\">.<\/span><span class=\"token function\">deductStock<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;SKU_BREAD_003&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">400<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u8d85\u5356\u6263\u51cf\u7ed3\u679c: &#034;<\/span> <span class=\"token operator\">&#043;<\/span> oversell<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ false<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u4ee3\u7801\u91cc\u6709\u51e0\u4e2a\u8bbe\u8ba1\u503c\u5f97\u8bf4\u4e00\u4e0b&#xff1a;<\/p>\n<li>\u6279\u91cf\u5bfc\u5165\u7528\u666e\u901a HashMap \u505a\u4e34\u65f6\u5bb9\u5668&#xff1a;ConcurrentHashMap \u7684\u5e76\u53d1\u63a7\u5236\u662f\u6709\u5f00\u9500\u7684&#xff0c;\u5355\u7ebf\u7a0b\u6279\u91cf\u5904\u7406\u7684\u65f6\u5019\u7528\u666e\u901a HashMap \u66f4\u5feb&#xff0c;\u5904\u7406\u5b8c\u518d\u6574\u4f53 putAll \u8fdb\u53bb\u3002<\/li>\n<li>compute \u505a\u539f\u5b50\u6263\u51cf&#xff1a;ConcurrentHashMap \u7684 compute \u65b9\u6cd5\u662f\u539f\u5b50\u64cd\u4f5c&#xff0c;\u5728\u5355\u673a\u573a\u666f\u4e0b\u80fd\u4fdd\u8bc1\u4e0d\u8d85\u5356&#xff0c;\u6bd4 get &#043; \u5224\u65ad &#043; put \u8fd9\u79cd\u975e\u539f\u5b50\u7ec4\u5408\u5b89\u5168\u5f97\u591a\u3002<\/li>\n<li>\u521d\u59cb\u5316\u5bb9\u91cf\u7684\u9884\u4f30&#xff1a;\u590d\u7528\u4e86 HashMap \u5185\u90e8\u7684 tableSizeFor \u65b9\u6cd5\u903b\u8f91&#xff0c;\u786e\u4fdd\u521d\u59cb\u5bb9\u91cf\u662f 2 \u7684\u5e42&#xff0c;\u4e14\u8db3\u591f\u5bb9\u7eb3\u9884\u671f\u6570\u91cf\u7684\u5143\u7d20&#xff0c;\u907f\u514d\u6269\u5bb9\u3002<\/li>\n<h3>\u516b\u3001\u9762\u8bd5\u9ad8\u9891\u95ee\u9898\u4e0e\u6211\u7684\u7406\u89e3<\/h3>\n<p>\u65e2\u7136\u8bb2\u5230\u8fd9\u91cc\u4e86&#xff0c;\u987a\u5e26\u628a HashMap \u76f8\u5173\u7684\u9ad8\u9891\u9762\u8bd5\u9898\u4e5f\u68b3\u7406\u4e00\u4e0b&#xff0c;\u7b97\u662f\u5e2e\u5927\u5bb6\u628a\u5b66\u5230\u7684\u77e5\u8bc6\u505a\u4e2a\u5e94\u7528&#xff1a;<\/p>\n<p>Q1&#xff1a;HashMap \u7684\u521d\u59cb\u5bb9\u91cf\u662f\u591a\u5c11&#xff1f;\u8d1f\u8f7d\u56e0\u5b50\u662f\u591a\u5c11&#xff1f;\u4e3a\u4ec0\u4e48\u9ed8\u8ba4\u8fd9\u4e9b\u503c&#xff1f;<\/p>\n<p>\u521d\u59cb\u5bb9\u91cf 16&#xff0c;\u8d1f\u8f7d\u56e0\u5b50 0.75\u3002\u5bb9\u91cf\u5fc5\u987b\u662f 2 \u7684\u5e42&#xff0c;\u65b9\u4fbf\u7528\u4f4d\u8fd0\u7b97\u4ee3\u66ff\u53d6\u6a21&#xff08;h &amp; (n-1) vs h % n&#xff09;\u3002\u8d1f\u8f7d\u56e0\u5b50 0.75 \u662f\u7a7a\u95f4\u548c\u65f6\u95f4\u7684\u5e73\u8861\u503c&#xff1a;\u592a\u5927\u4e86\u51b2\u7a81\u591a&#xff0c;\u592a\u5c0f\u4e86\u6d6a\u8d39\u7a7a\u95f4&#xff0c;\u5b98\u65b9\u6587\u6863\u63d0\u5230\u8fd9\u662f\u57fa\u4e8e\u6cca\u677e\u5206\u5e03\u9009\u51fa\u7684\u4e00\u4e2a\u7ecf\u9a8c\u503c\u3002<\/p>\n<p>Q2&#xff1a;HashMap \u7684 key \u53ef\u4ee5\u662f null \u5417&#xff1f;<\/p>\n<p>\u53ef\u4ee5&#xff0c;\u800c\u4e14\u53ea\u80fd\u6709\u4e00\u4e2a null key&#xff0c;\u4f1a\u88ab\u6620\u5c04\u5230\u6570\u7ec4\u4e0b\u6807 0\u3002Hashtable \u4e0d\u5141\u8bb8 null key\u3002<\/p>\n<p>Q3&#xff1a;\u4e3a\u4ec0\u4e48 HashMap \u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168\u7684&#xff1f;<\/p>\n<p>JDK 1.7&#xff1a;\u5e76\u53d1\u6269\u5bb9\u65f6\u5934\u63d2\u6cd5\u5bfc\u81f4\u94fe\u8868\u6210\u73af&#xff0c;get \u64cd\u4f5c\u65e0\u9650\u5faa\u73af&#xff0c;CPU 100%\u3002 JDK 1.8&#xff1a;\u5c3e\u63d2\u6cd5\u89e3\u51b3\u4e86\u6b7b\u5faa\u73af&#xff0c;\u4f46\u5e76\u53d1 put \u65f6\u4ecd\u7136\u53ef\u80fd\u4e22\u5931\u6570\u636e&#xff08;\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u5224\u65ad\u94fe\u8868\u5c3e\u8282\u70b9\u4e3a null&#xff0c;\u540e\u5199\u7684\u8986\u76d6\u524d\u5199\u7684&#xff09;\u3002<\/p>\n<p>Q4&#xff1a;HashMap \u548c LinkedHashMap\u3001TreeMap \u7684\u533a\u522b&#xff1f;<\/p>\n<ul>\n<li>HashMap&#xff1a;\u65e0\u5e8f&#xff0c;\u67e5\u627e O(1)&#xff0c;\u4e0d\u4fdd\u8bc1\u8fed\u4ee3\u987a\u5e8f<\/li>\n<li>LinkedHashMap&#xff1a;\u7ef4\u62a4\u63d2\u5165\u987a\u5e8f\u6216\u8bbf\u95ee\u987a\u5e8f&#xff08;\u53cc\u5411\u94fe\u8868&#xff09;&#xff0c;\u53ef\u7528\u6765\u5b9e\u73b0 LRU \u7f13\u5b58<\/li>\n<li>TreeMap&#xff1a;\u6309 key \u7684\u81ea\u7136\u987a\u5e8f\u6216 Comparator \u6392\u5e8f&#xff0c;\u57fa\u4e8e\u7ea2\u9ed1\u6811&#xff0c;\u67e5\u627e O(log n)<\/li>\n<\/ul>\n<p>Q5&#xff1a;JDK 1.8 \u7684\u7ea2\u9ed1\u6811\u5316&#xff0c;\u4ec0\u4e48\u65f6\u5019\u89e6\u53d1&#xff1f;<\/p>\n<p>\u4e24\u4e2a\u6761\u4ef6\u540c\u65f6\u6ee1\u8db3&#xff1a;\u2460 \u94fe\u8868\u957f\u5ea6 \u2265 8&#xff1b;\u2461 \u6570\u7ec4\u957f\u5ea6 \u2265 64\u3002\u5982\u679c\u6570\u7ec4\u957f\u5ea6 &lt; 64 \u4f46\u94fe\u8868\u957f\u5ea6 \u2265 8&#xff0c;\u4f1a\u4f18\u5148\u9009\u62e9\u6269\u5bb9\u800c\u4e0d\u662f\u6811\u5316\u3002<\/p>\n<h3>\u4e5d\u3001\u603b\u7ed3\u4e0e\u601d\u8003<\/h3>\n<p>\u56de\u8fc7\u5934\u6765\u770b&#xff0c;JDK 1.8 \u5bf9 HashMap \u7684\u6539\u8fdb&#xff0c;\u672c\u8d28\u4e0a\u662f\u5728\u89e3\u51b3\u4e00\u4e2a\u95ee\u9898&#xff1a;\u5982\u4f55\u5728\u4fdd\u8bc1\u67e5\u627e\u6027\u80fd\u7684\u524d\u63d0\u4e0b&#xff0c;\u5e94\u5bf9\u6781\u7aef\u7684\u54c8\u5e0c\u51b2\u7a81\u573a\u666f&#xff1f;<\/p>\n<p>JDK 1.7 \u7684\u65b9\u6848\u662f&#xff1a;\u66f4\u597d\u7684\u54c8\u5e0c\u7b97\u6cd5&#xff08;\u56db\u6b21\u6270\u52a8&#xff09;&#xff0c;\u8ba9\u51b2\u7a81\u5c3d\u91cf\u5c11\u53d1\u751f\u3002<\/p>\n<p>JDK 1.8 \u7684\u65b9\u6848\u662f&#xff1a;\u4e00\u65b9\u9762\u7b80\u5316\u54c8\u5e0c\u7b97\u6cd5&#xff08;\u51cf\u5c11\u8ba1\u7b97\u5f00\u9500&#xff09;&#xff0c;\u53e6\u4e00\u65b9\u9762\u5f15\u5165\u7ea2\u9ed1\u6811\u505a\u515c\u5e95&#xff08;\u5c31\u7b97\u51b2\u7a81\u53d1\u751f\u4e86&#xff0c;\u67e5\u627e\u4e5f\u80fd\u7ef4\u6301 O(log n) \u800c\u4e0d\u662f\u9000\u5316\u5230 O(n)&#xff09;\u3002<\/p>\n<p>\u540c\u65f6&#xff0c;\u628a\u5934\u63d2\u6cd5\u6539\u6210\u5c3e\u63d2\u6cd5&#xff0c;\u6d88\u9664\u4e86\u5e76\u53d1\u6269\u5bb9\u65f6\u7684\u6b7b\u5faa\u73af\u98ce\u9669&#xff0c;\u8ba9 HashMap \u7684\u884c\u4e3a\u5728\u591a\u7ebf\u7a0b\u573a\u666f\u4e0b\u66f4\u53ef\u9884\u671f&#xff08;\u867d\u7136\u8fd8\u662f\u4e0d\u5b89\u5168&#xff0c;\u4f46\u81f3\u5c11\u4e0d\u4f1a\u628a\u670d\u52a1\u641e\u6b7b&#xff09;\u3002<\/p>\n<p>\u5de5\u7a0b\u4e0a&#xff0c;\u8bb0\u4f4f\u51e0\u4e2a\u539f\u5219&#xff1a;<\/p>\n<li>\u5355\u7ebf\u7a0b\u7528 HashMap&#xff0c;\u591a\u7ebf\u7a0b\u7528 ConcurrentHashMap&#xff0c;\u575a\u51b3\u4e0d\u7528 Hashtable<\/li>\n<li>\u77e5\u9053\u6570\u636e\u91cf\u7684\u65f6\u5019&#xff0c;\u6307\u5b9a\u521d\u59cb\u5bb9\u91cf&#xff0c;\u51cf\u5c11\u6269\u5bb9\u5f00\u9500<\/li>\n<li>key \u8981\u7528\u4e0d\u53ef\u53d8\u7c7b\u578b&#xff0c;\u6216\u8005\u786e\u4fdd hashCode \u548c equals \u5b9e\u73b0\u6b63\u786e<\/li>\n<li>\u5982\u679c\u9700\u8981\u6709\u5e8f&#xff0c;\u8003\u8651 LinkedHashMap&#xff08;\u7ef4\u62a4\u63d2\u5165\u987a\u5e8f&#xff09;\u6216 TreeMap&#xff08;\u6309 key \u6392\u5e8f&#xff09;<\/li>\n<p>\u6700\u540e\u8bf4\u4e00\u53e5&#xff1a;\u8fd9\u4e9b\u539f\u7406\u4e0d\u662f\u4e3a\u4e86\u80cc\u9762\u8bd5\u9898\u800c\u5b58\u5728\u7684\u3002\u771f\u6b63\u641e\u61c2\u4e86&#xff0c;\u4f60\u624d\u80fd\u5728\u751f\u4ea7\u73af\u5883\u51fa\u95ee\u9898\u7684\u51cc\u6668\u4e09\u70b9&#xff0c;\u4e0d\u662f\u832b\u7136\u5730\u770b\u7740\u5d29\u6389\u7684\u670d\u52a1&#xff0c;\u800c\u662f\u6709\u6761\u4e0d\u7d0a\u5730\u5b9a\u4f4d\u95ee\u9898&#xff0c;\u4e09\u5206\u949f\u7ed9\u51fa\u89e3\u51b3\u65b9\u6848\u3002<\/p>\n<p>\u90a3\u79cd\u611f\u89c9&#xff0c;\u771f\u7684\u4e0d\u4e00\u6837\u3002<\/p>\n<h3>&#x1f31f; 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