{"id":89064,"date":"2026-08-02T10:57:07","date_gmt":"2026-08-02T02:57:07","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/89064.html"},"modified":"2026-08-02T10:57:07","modified_gmt":"2026-08-02T02:57:07","slug":"30-%e3%80%90java%e3%80%91%e9%9b%86%e5%90%88%e6%a1%86%e6%9e%b6%ef%bc%88%e4%b8%ad%ef%bc%89%ef%bc%9amap-%e4%b8%8e-queue","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/89064.html","title":{"rendered":"30. \u3010Java\u3011\u96c6\u5408\u6846\u67b6\uff08\u4e2d\uff09\uff1aMap \u4e0e Queue"},"content":{"rendered":"<p>\u6458\u8981&#xff1a; \u672c\u6587\u6df1\u5165\u8bb2\u89e3Java\u96c6\u5408\u6846\u67b6\u4e2d\u7684Map\u548cQueue\u4e24\u5927\u6838\u5fc3\u63a5\u53e3\u3002Map\u4f5c\u4e3a\u952e\u503c\u5bf9\u6620\u5c04\u5bb9\u5668&#xff0c;\u6db5\u76d6HashMap\u3001LinkedHashMap\u548cTreeMap\u7684\u5b9e\u73b0\u539f\u7406\u4e0e\u4f7f\u7528\u573a\u666f&#xff1b;Queue\u4f5c\u4e3a\u5148\u8fdb\u5148\u51fa\u961f\u5217&#xff0c;\u4ecb\u7ecdLinkedList\u3001ArrayDeque\u548cPriorityQueue\u7684\u5b9e\u8df5\u5e94\u7528\u3002\u6587\u7ae0\u901a\u8fc7\u4e30\u5bcc\u4ee3\u7801\u793a\u4f8b\u5c55\u793a\u904d\u5386\u65b9\u5f0f\u3001\u952e\u552f\u4e00\u6027\u539f\u7406\u3001\u9009\u62e9\u6307\u5357\u53ca\u5e38\u89c1\u9677\u9631&#xff0c;\u5e2e\u52a9\u5f00\u53d1\u8005\u638c\u63e1\u8fd9\u4e24\u79cd\u5728\u65e5\u5e38\u5f00\u53d1\u4e2d\u9ad8\u9891\u4f7f\u7528\u7684\u6570\u636e\u7ed3\u6784&#xff0c;\u63d0\u5347\u7f16\u7a0b\u6548\u7387\u4e0e\u4ee3\u7801\u8d28\u91cf\u3002<\/p>\n<p>\u5173\u952e\u8bcd&#xff1a; Java\u96c6\u5408\u6846\u67b6, Map\u6620\u5c04, Queue\u961f\u5217, HashMap, \u6570\u636e\u7ed3\u6784<\/p>\n<hr \/>\n<p>\u4e0a\u4e00\u7bc7\u6587\u7ae0\u6211\u4eec\u8ba4\u8bc6\u4e86 List \u548c Set&#xff0c;\u5b83\u4eec\u90fd\u662f\u201c\u5355\u4e2a\u5143\u7d20\u201d\u7684\u5bb9\u5668\u3002\u4f60\u5f80\u91cc\u9762\u653e\u4e00\u4e2a\u4e1c\u897f&#xff0c;\u5b83\u7ed9\u4f60\u5b58\u8d77\u6765&#xff1b;\u4f60\u53d6\u51fa\u6765\u7684\u65f6\u5019&#xff0c;\u5f97\u5230\u7684\u662f\u90a3\u4e2a\u4e1c\u897f\u672c\u8eab\u3002<\/p>\n<p>\u4f46\u73b0\u5b9e\u4e2d\u7684\u6570\u636e\u7ed3\u6784&#xff0c;\u8fd8\u6709\u4e00\u79cd\u975e\u5e38\u5e38\u89c1\u7684\u6a21\u5f0f&#xff1a;\u201c\u6839\u636e\u67d0\u4e2a\u4e1c\u897f&#xff0c;\u627e\u5230\u53e6\u4e00\u4e2a\u4e1c\u897f\u201d\u3002<\/p>\n<p>\u6bd4\u5982&#xff1a;<\/p>\n<ul>\n<li>\u6839\u636e\u201c\u5b66\u53f7\u201d\u627e\u5230\u201c\u5b66\u751f\u5bf9\u8c61\u201d<\/li>\n<li>\u6839\u636e\u201c\u7528\u6237\u540d\u201d\u627e\u5230\u201c\u7528\u6237\u4fe1\u606f\u201d<\/li>\n<li>\u6839\u636e\u201c\u5546\u54c1ID\u201d\u627e\u5230\u201c\u5546\u54c1\u8be6\u60c5\u201d<\/li>\n<li>\u6839\u636e\u201c\u5355\u8bcd\u201d\u627e\u5230\u201c\u5b83\u7684\u91ca\u4e49\u201d<\/li>\n<\/ul>\n<p>\u8fd9\u79cd\u201c\u952e \u2192 \u503c\u201d\u7684\u6620\u5c04\u5173\u7cfb&#xff0c;\u5728\u7a0b\u5e8f\u4e16\u754c\u91cc\u65e0\u5904\u4e0d\u5728\u3002\u5728 Java \u4e2d&#xff0c;\u8868\u8fbe\u8fd9\u79cd\u5173\u7cfb\u7684\u6570\u636e\u7ed3\u6784\u5c31\u662f Map&#xff08;\u6620\u5c04&#xff09;\u3002<\/p>\n<p>\u6b64\u5916&#xff0c;\u8fd8\u6709\u4e00\u79cd\u975e\u5e38\u57fa\u7840\u7684\u6570\u636e\u7ed3\u6784\u53eb Queue&#xff08;\u961f\u5217&#xff09;\u2014\u2014\u5b83\u5c31\u50cf\u6392\u961f\u4e70\u7968\u4e00\u6837&#xff0c;\u5148\u5230\u5148\u5f97&#xff0c;\u5148\u8fdb\u5148\u51fa&#xff08;FIFO&#xff09;\u3002<\/p>\n<p>\u4eca\u5929&#xff0c;\u6211\u4eec\u5c31\u6765\u6df1\u5165\u5b66\u4e60 Map \u548c Queue&#xff0c;\u5b83\u4eec\u662f\u96c6\u5408\u6846\u67b6\u4e2d\u53e6\u5916\u4e24\u4e2a\u6781\u5176\u91cd\u8981\u7684\u6210\u5458\u3002<\/p>\n<hr \/>\n<h4>1. Map \u63a5\u53e3 \u2014\u2014 \u952e\u503c\u5bf9\u7684\u201c\u5b57\u5178\u201d<\/h4>\n<p>Map \u548c Collection \u662f\u5e73\u7ea7\u7684\u4e24\u5927\u63a5\u53e3\u4f53\u7cfb\u3002Map \u4e0d\u7ee7\u627f Collection&#xff0c;\u5b83\u6709\u81ea\u5df1\u7684\u7ed3\u6784\u3002<\/p>\n<p>Map \u7684\u7279\u70b9&#xff1a;<\/p>\n<ul>\n<li>\u5b58\u50a8\u952e\u503c\u5bf9&#xff08;Key-Value Pair&#xff09;\u3002<\/li>\n<li>\u952e&#xff08;Key&#xff09;\u662f\u552f\u4e00\u7684&#xff0c;\u4e0d\u80fd\u91cd\u590d&#xff08;\u901a\u8fc7 equals() \u548c hashCode() \u5224\u65ad&#xff09;\u3002<\/li>\n<li>\u503c&#xff08;Value&#xff09;\u53ef\u4ee5\u91cd\u590d\u3002<\/li>\n<li>\u6bcf\u4e2a\u952e\u6700\u591a\u6620\u5c04\u5230\u4e00\u4e2a\u503c\u3002<\/li>\n<\/ul>\n<p>\u6211\u4eec\u6700\u5e38\u7528\u7684\u4e09\u4e2a Map \u5b9e\u73b0\u662f&#xff1a;HashMap\u3001LinkedHashMap \u548c TreeMap\u3002<\/p>\n<h5>1.1 HashMap \u2014\u2014 \u57fa\u4e8e\u54c8\u5e0c\u8868\u7684\u6620\u5c04<\/h5>\n<p>HashMap \u662f\u6700\u5e38\u7528\u7684 Map \u5b9e\u73b0\u3002\u5b83\u57fa\u4e8e\u54c8\u5e0c\u8868&#xff0c;\u67e5\u627e\u3001\u63d2\u5165\u3001\u5220\u9664\u7684\u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6\u4e3a O(1)\u3002<\/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><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">HashMapDemo<\/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 comment\">\/\/ \u521b\u5efa HashMap&#xff0c;\u952e\u662f String&#xff08;\u5b66\u53f7&#xff09;&#xff0c;\u503c\u662f Student \u5bf9\u8c61<\/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\">Student<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> studentMap <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\">\/\/ 1. \u6dfb\u52a0\u952e\u503c\u5bf9<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> s1 <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Student<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5f20\u4e09&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">20<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;S001&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> s2 <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Student<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u674e\u56db&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">21<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;S002&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> s3 <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Student<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u738b\u4e94&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">19<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;S003&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S001&#034;<\/span><span class=\"token punctuation\">,<\/span> s1<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S002&#034;<\/span><span class=\"token punctuation\">,<\/span> s2<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S003&#034;<\/span><span class=\"token punctuation\">,<\/span> s3<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 2. \u6839\u636e\u952e\u83b7\u53d6\u503c<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> found <span class=\"token operator\">&#061;<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">get<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S002&#034;<\/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;\u5b66\u53f7 S002 \u7684\u5b66\u751f&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> found<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u674e\u56db<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u5982\u679c\u952e\u4e0d\u5b58\u5728&#xff0c;get() \u8fd4\u56de null<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> notFound <span class=\"token operator\">&#061;<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">get<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S999&#034;<\/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;S999&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> notFound<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ null<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 3. \u83b7\u53d6\u5e26\u9ed8\u8ba4\u503c\u7684&#xff08;JDK 8&#043;&#xff09;<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> defaultStudent <span class=\"token operator\">&#061;<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">getOrDefault<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S999&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Student<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u9ed8\u8ba4&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">0<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;DEFAULT&#034;<\/span><span class=\"token punctuation\">)<\/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;\u9ed8\u8ba4\u5b66\u751f&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> defaultStudent<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 4. \u68c0\u67e5\u662f\u5426\u5305\u542b\u67d0\u4e2a\u952e\u6216\u503c<\/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;\u662f\u5426\u5305\u542b\u952e S001&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">containsKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S001&#034;<\/span><span class=\"token punctuation\">)<\/span><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;\u662f\u5426\u5305\u542b\u5b66\u751f\u5f20\u4e09&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">containsValue<\/span><span class=\"token punctuation\">(<\/span>s1<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ true<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 5. \u66ff\u6362\u503c<\/span><br \/>\n        <span class=\"token class-name\">Student<\/span> newS2 <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">Student<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u674e\u56db\u6539\u540d&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">22<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;S002&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S002&#034;<\/span><span class=\"token punctuation\">,<\/span> newS2<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u76f8\u540c\u7684\u952e\u4f1a\u8986\u76d6\u65e7\u503c<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 6. \u5220\u9664\u952e\u503c\u5bf9<\/span><br \/>\n        studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">remove<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;S003&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ 7. \u83b7\u53d6\u5927\u5c0f<\/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;Map \u5927\u5c0f&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> studentMap<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> <span class=\"token comment\">\/\/ 2<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h5>1.2 LinkedHashMap \u2014\u2014 \u4fdd\u7559\u63d2\u5165\u987a\u5e8f\u7684 HashMap<\/h5>\n<p>LinkedHashMap \u662f HashMap \u7684\u5b50\u7c7b\u3002\u5b83\u5728\u54c8\u5e0c\u8868\u7684\u57fa\u7840\u4e0a\u589e\u52a0\u4e86\u4e00\u4e2a\u53cc\u5411\u94fe\u8868&#xff0c;\u7ef4\u62a4\u4e86\u952e\u503c\u5bf9\u7684\u63d2\u5165\u987a\u5e8f&#xff08;\u6216\u8bbf\u95ee\u987a\u5e8f&#xff0c;\u53d6\u51b3\u4e8e\u6784\u9020\u53c2\u6570&#xff09;\u3002<\/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> linkedMap <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">LinkedHashMap<\/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 \/>\nlinkedMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;apple&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;\u82f9\u679c&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\nlinkedMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;banana&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;\u9999\u8549&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\nlinkedMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;orange&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token string\">&#034;\u6a58\u5b50&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u904d\u5386\u987a\u5e8f\u4e0e\u63d2\u5165\u987a\u5e8f\u4e00\u81f4&#xff1a;apple \u2192 banana \u2192 orange<\/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> linkedMap<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\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/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 operator\">&#043;<\/span> <span class=\"token string\">&#034; &#061; &#034;<\/span> <span class=\"token operator\">&#043;<\/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><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u7528\u9014&#xff1a;\u5f53\u4f60\u9700\u8981\u4fdd\u7559\u63d2\u5165\u987a\u5e8f\u65f6&#xff08;\u6bd4\u5982\u5b9e\u73b0 LRU \u7f13\u5b58&#xff09;&#xff0c;LinkedHashMap \u5f88\u5408\u9002\u3002<\/p>\n<h5>1.3 TreeMap \u2014\u2014 \u57fa\u4e8e\u7ea2\u9ed1\u6811\u7684\u6709\u5e8f\u6620\u5c04<\/h5>\n<p>TreeMap \u57fa\u4e8e\u7ea2\u9ed1\u6811\u5b9e\u73b0&#xff0c;\u5b83\u4f1a\u6839\u636e\u952e\u7684\u81ea\u7136\u987a\u5e8f&#xff08;\u6216\u81ea\u5b9a\u4e49\u6bd4\u8f83\u5668&#xff09;\u5bf9\u952e\u8fdb\u884c\u6392\u5e8f\u3002<\/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\">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><\/span><span class=\"token class-name\">TreeMap<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">TreeMapDemo<\/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 comment\">\/\/ \u952e\u6309\u5b57\u5178\u5e8f\u5347\u5e8f\u6392\u5217<\/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> scores <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">TreeMap<\/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        scores<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5f20\u4e09&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">85<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        scores<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u674e\u56db&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">92<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        scores<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u738b\u4e94&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">78<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        scores<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u963f\u5f3a&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">88<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u904d\u5386\u65f6\u4f1a\u6309\u952e\u7684\u5b57\u5178\u5e8f\u8f93\u51fa&#xff1a;\u963f\u5f3a\u3001\u674e\u56db\u3001\u738b\u4e94\u3001\u5f20\u4e09<\/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\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> entry <span class=\"token operator\">:<\/span> scores<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\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/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 operator\">&#043;<\/span> <span class=\"token string\">&#034;: &#034;<\/span> <span class=\"token operator\">&#043;<\/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><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ TreeMap \u63d0\u4f9b\u4e86\u989d\u5916\u7684\u5bfc\u822a\u65b9\u6cd5<\/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;\u7b2c\u4e00\u4e2a\u952e&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">TreeMap<\/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 punctuation\">)<\/span> scores<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">.<\/span><span class=\"token function\">firstKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u963f\u5f3a<\/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;\u6700\u540e\u4e00\u4e2a\u952e&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">TreeMap<\/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 punctuation\">)<\/span> scores<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">.<\/span><span class=\"token function\">lastKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u5f20\u4e09<\/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;\u5927\u4e8e\u7b49\u4e8e\u674e\u56db\u7684\u952e&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">TreeMap<\/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 punctuation\">)<\/span> scores<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">.<\/span><span class=\"token function\">ceilingKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u674e\u56db&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span> <span class=\"token comment\">\/\/ \u674e\u56db<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>TreeMap \u7684\u7528\u9014&#xff1a;\u5f53\u9700\u8981\u6309\u952e\u6392\u5e8f\u65f6&#xff08;\u6bd4\u5982\u6309\u65f6\u95f4\u6233\u6392\u5e8f\u7684\u65e5\u5fd7\u3001\u6309\u540d\u79f0\u6392\u5e8f\u7684\u5b57\u5178&#xff09;\u3002<\/p>\n<hr \/>\n<h4>2. \u904d\u5386 Map \u2014\u2014 \u4e09\u79cd\u65b9\u5f0f<\/h4>\n<p>Map \u4e0d\u76f4\u63a5\u5b9e\u73b0 Iterable&#xff0c;\u6240\u4ee5\u4e0d\u80fd\u76f4\u63a5\u7528\u589e\u5f3a for \u904d\u5386\u3002\u5b83\u63d0\u4f9b\u4e86\u4e09\u79cd\u201c\u89c6\u56fe\u201d\u6765\u904d\u5386&#xff1a;<\/p>\n<h5>\u2460 \u904d\u5386\u952e&#xff08;keySet()&#xff09;<\/h5>\n<p><span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> key <span class=\"token operator\">:<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">keySet<\/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\">Student<\/span> student <span class=\"token operator\">&#061;<\/span> studentMap<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><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>key <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034; \u2192 &#034;<\/span> <span class=\"token operator\">&#043;<\/span> student<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/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<h5>\u2461 \u904d\u5386\u503c&#xff08;values()&#xff09;<\/h5>\n<p><span class=\"token keyword\">for<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Student<\/span> student <span class=\"token operator\">:<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">values<\/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\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span>student<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/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<h5>\u2462 \u904d\u5386\u952e\u503c\u5bf9&#xff08;entrySet()&#xff09;\u2014\u2014 \u6700\u5e38\u7528&#xff0c;\u6548\u7387\u6700\u9ad8<\/h5>\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\">Student<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> entry <span class=\"token operator\">:<\/span> studentMap<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> key <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\">Student<\/span> value <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><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>key <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034; \u2192 &#034;<\/span> <span class=\"token operator\">&#043;<\/span> value<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/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>entrySet() \u8fd4\u56de\u7684\u662f Map.Entry \u5bf9\u8c61\u96c6\u5408&#xff0c;\u6bcf\u4e2a Entry \u5305\u542b\u4e00\u4e2a\u952e\u548c\u4e00\u4e2a\u503c\u3002\u8fd9\u79cd\u65b9\u5f0f\u5728\u904d\u5386\u65f6\u4e0d\u9700\u8981\u4e8c\u6b21\u67e5\u627e&#xff08;get(key)&#xff09;&#xff0c;\u6027\u80fd\u6700\u597d\u3002<\/p>\n<h5>JDK 8&#043; \u7684 forEach \u65b9\u6cd5&#xff08;Lambda&#xff09;<\/h5>\n<p>studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">forEach<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>key<span class=\"token punctuation\">,<\/span> value<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">-&gt;<\/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>key <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034; \u2192 &#034;<\/span> <span class=\"token operator\">&#043;<\/span> value<span class=\"token punctuation\">.<\/span><span class=\"token function\">getName<\/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><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>\u8fd9\u662f\u6700\u7b80\u6d01\u7684\u904d\u5386\u65b9\u5f0f&#xff0c;\u9002\u5408\u7b80\u5355\u7684\u904d\u5386\u64cd\u4f5c\u3002<\/p>\n<hr \/>\n<h4>3. Map \u4e2d\u952e\u7684\u552f\u4e00\u6027 \u2014\u2014 hashCode() \u548c equals()<\/h4>\n<p>\u548c HashSet \u4e00\u6837&#xff0c;HashMap \u548c LinkedHashMap \u4f9d\u8d56\u952e\u7684 hashCode() \u548c equals() \u6765\u5224\u65ad\u952e\u662f\u5426\u76f8\u540c\u3002<\/p>\n<p>\u5982\u679c\u4f60\u7528\u81ea\u5b9a\u4e49\u7c7b\u4f5c\u4e3a Map \u7684\u952e&#xff0c;\u5fc5\u987b\u6b63\u786e\u91cd\u5199 hashCode() \u548c equals()&#xff0c;\u5426\u5219\u76f8\u540c\u7684\u5bf9\u8c61\u53ef\u80fd\u4f1a\u88ab\u89c6\u4e3a\u4e0d\u540c\u7684\u952e&#xff0c;\u5bfc\u81f4\u6570\u636e\u9519\u4e71\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u81ea\u5b9a\u4e49\u7c7b\u4f5c\u4e3a\u952e&#xff08;\u5fc5\u987b\u91cd\u5199 hashCode \u548c equals&#xff09;<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">ProductKey<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token class-name\">String<\/span> category<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token keyword\">private<\/span> <span class=\"token class-name\">String<\/span> id<span class=\"token punctuation\">;<\/span><\/p>\n<p>    <span class=\"token keyword\">public<\/span> <span class=\"token class-name\">ProductKey<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> category<span class=\"token punctuation\">,<\/span> <span class=\"token class-name\">String<\/span> id<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">this<\/span><span class=\"token punctuation\">.<\/span>category <span class=\"token operator\">&#061;<\/span> category<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">this<\/span><span class=\"token punctuation\">.<\/span>id <span class=\"token operator\">&#061;<\/span> id<span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token annotation punctuation\">&#064;Override<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">boolean<\/span> <span class=\"token function\">equals<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Object<\/span> o<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 keyword\">this<\/span> <span class=\"token operator\">&#061;&#061;<\/span> o<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">return<\/span> <span class=\"token boolean\">true<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>o <span class=\"token operator\">&#061;&#061;<\/span> <span class=\"token keyword\">null<\/span> <span class=\"token operator\">||<\/span> <span class=\"token function\">getClass<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">!&#061;<\/span> o<span class=\"token punctuation\">.<\/span><span class=\"token function\">getClass<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">return<\/span> <span class=\"token boolean\">false<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token class-name\">ProductKey<\/span> that <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token class-name\">ProductKey<\/span><span class=\"token punctuation\">)<\/span> o<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> category<span class=\"token punctuation\">.<\/span><span class=\"token function\">equals<\/span><span class=\"token punctuation\">(<\/span>that<span class=\"token punctuation\">.<\/span>category<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&amp;&amp;<\/span> id<span class=\"token punctuation\">.<\/span><span class=\"token function\">equals<\/span><span class=\"token punctuation\">(<\/span>that<span class=\"token punctuation\">.<\/span>id<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><\/p>\n<p>    <span class=\"token annotation punctuation\">&#064;Override<\/span><br \/>\n    <span class=\"token keyword\">public<\/span> <span class=\"token keyword\">int<\/span> <span class=\"token function\">hashCode<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">return<\/span> <span class=\"token number\">31<\/span> <span class=\"token operator\">*<\/span> category<span class=\"token punctuation\">.<\/span><span class=\"token function\">hashCode<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#043;<\/span> id<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><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>&#x1f4a1; \u5bf9\u4e8e String\u3001Integer \u7b49 JDK \u7c7b&#xff0c;\u5b83\u4eec\u5df2\u7ecf\u6b63\u786e\u91cd\u5199\u4e86\u8fd9\u4e24\u4e2a\u65b9\u6cd5&#xff0c;\u6240\u4ee5\u53ef\u4ee5\u76f4\u63a5\u4f5c\u4e3a\u952e\u4f7f\u7528\u3002<\/p>\n<hr \/>\n<h4>4. Map \u7684\u9009\u62e9\u6307\u5357<\/h4>\n<table>\n<tr>\u9700\u6c42\u63a8\u8350<\/tr>\n<tbody>\n<tr>\n<td>\u6700\u5feb\u7684\u67e5\u627e\u901f\u5ea6&#xff0c;\u4e0d\u5173\u5fc3\u987a\u5e8f<\/td>\n<td>HashMap<\/td>\n<\/tr>\n<tr>\n<td>\u9700\u8981\u4fdd\u7559\u63d2\u5165\u987a\u5e8f<\/td>\n<td>LinkedHashMap<\/td>\n<\/tr>\n<tr>\n<td>\u9700\u8981\u6309\u952e\u6392\u5e8f&#xff08;\u5347\u5e8f\/\u81ea\u5b9a\u4e49&#xff09;<\/td>\n<td>TreeMap<\/td>\n<\/tr>\n<tr>\n<td>\u9700\u8981\u7ebf\u7a0b\u5b89\u5168&#xff08;\u4e0d\u63a8\u8350&#xff0c;\u7528 ConcurrentHashMap&#xff09;<\/td>\n<td>ConcurrentHashMap&#xff08;\u6211\u4eec\u540e\u9762\u4f1a\u8bb2&#xff09;<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u5728\u65e5\u5e38\u5f00\u53d1\u4e2d&#xff0c;HashMap \u7684\u4f7f\u7528\u9891\u7387\u6700\u9ad8&#xff0c;\u7ea6\u5360 90% \u4ee5\u4e0a\u3002<\/p>\n<hr \/>\n<h4>5. Queue \u63a5\u53e3 \u2014\u2014 \u5148\u8fdb\u5148\u51fa\u7684\u201c\u961f\u5217\u201d<\/h4>\n<p>Queue \u662f Collection \u7684\u5b50\u63a5\u53e3&#xff0c;\u4ee3\u8868\u4e00\u4e2a\u961f\u5217&#xff08;Queue&#xff09;\u2014\u2014\u4e00\u79cd\u5148\u8fdb\u5148\u51fa&#xff08;FIFO&#xff09;\u7684\u6570\u636e\u7ed3\u6784\u3002\u5c31\u50cf\u6392\u961f\u4e70\u7968&#xff1a;\u5148\u6765\u7684\u4eba\u5148\u4e70\u5230&#xff0c;\u540e\u6765\u7684\u4eba\u6392\u5728\u540e\u9762\u3002<\/p>\n<p>Queue \u63d0\u4f9b\u4e86\u4e24\u7c7b\u64cd\u4f5c&#xff1a;<\/p>\n<ul>\n<li>\u6dfb\u52a0&#xff1a;offer()&#xff08;\u63a8\u8350&#xff0c;\u5931\u8d25\u8fd4\u56de false&#xff09; vs add()&#xff08;\u5931\u8d25\u629b\u5f02\u5e38&#xff09;<\/li>\n<li>\u53d6\u51fa\u5e76\u79fb\u9664&#xff1a;poll()&#xff08;\u63a8\u8350&#xff0c;\u961f\u5217\u7a7a\u8fd4\u56de null&#xff09; vs remove()&#xff08;\u7a7a\u629b\u5f02\u5e38&#xff09;<\/li>\n<li>\u67e5\u770b\u4f46\u4e0d\u79fb\u9664&#xff1a;peek()&#xff08;\u63a8\u8350&#xff0c;\u7a7a\u8fd4\u56de null&#xff09; vs element()&#xff08;\u7a7a\u629b\u5f02\u5e38&#xff09;<\/li>\n<\/ul>\n<p>\u6700\u5e38\u7528\u7684 Queue \u5b9e\u73b0\u662f LinkedList&#xff08;\u5b83\u5b9e\u73b0\u4e86 Queue \u63a5\u53e3&#xff09;\u548c ArrayDeque\u3002<\/p>\n<h5>5.1 \u57fa\u672c\u7528\u6cd5<\/h5>\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\">LinkedList<\/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\">Queue<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">QueueDemo<\/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 comment\">\/\/ LinkedList \u5b9e\u73b0\u4e86 Queue \u63a5\u53e3<\/span><br \/>\n        <span class=\"token class-name\">Queue<\/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> queue <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">LinkedList<\/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\">\/\/ \u6dfb\u52a0\u5143\u7d20<\/span><br \/>\n        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u7b2c\u4e00\u4e2a\u4eba&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u7b2c\u4e8c\u4e2a\u4eba&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u7b2c\u4e09\u4e2a\u4eba&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u67e5\u770b\u961f\u9996\u5143\u7d20&#xff08;\u4e0d\u79fb\u9664&#xff09;<\/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;\u961f\u9996&#xff1a;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">peek<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7b2c\u4e00\u4e2a\u4eba<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u51fa\u961f&#xff1a;\u53d6\u51fa\u5e76\u79fb\u9664\u961f\u9996<\/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>queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7b2c\u4e00\u4e2a\u4eba<\/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>queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7b2c\u4e8c\u4e2a\u4eba<\/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>queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u7b2c\u4e09\u4e2a\u4eba<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u961f\u5217\u4e3a\u7a7a\u65f6&#xff0c;poll() \u8fd4\u56de null<\/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>queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ null<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<h5>5.2 ArrayDeque \u2014\u2014 \u66f4\u9ad8\u6548\u7684\u961f\u5217\/\u6808<\/h5>\n<p>ArrayDeque \u662f\u4e00\u4e2a\u57fa\u4e8e\u52a8\u6001\u6570\u7ec4\u7684\u53cc\u7aef\u961f\u5217&#xff08;Deque&#xff09;&#xff0c;\u5b83\u6bd4 LinkedList \u5728\u961f\u5217\u64cd\u4f5c\u4e0a\u6027\u80fd\u66f4\u597d&#xff0c;\u4e14\u4e0d\u652f\u6301 null \u5143\u7d20\u3002<\/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\">ArrayDeque<\/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\">Deque<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">ArrayDequeDemo<\/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 comment\">\/\/ \u4f5c\u4e3a\u961f\u5217\u4f7f\u7528&#xff08;FIFO&#xff09;<\/span><br \/>\n        <span class=\"token class-name\">Deque<\/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> queue <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ArrayDeque<\/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        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;A&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;B&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;C&#034;<\/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>queue<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ A<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u4f5c\u4e3a\u6808\u4f7f\u7528&#xff08;LIFO&#xff09;<\/span><br \/>\n        <span class=\"token class-name\">Deque<\/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> stack <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ArrayDeque<\/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        stack<span class=\"token punctuation\">.<\/span><span class=\"token function\">push<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;X&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u5165\u6808<\/span><br \/>\n        stack<span class=\"token punctuation\">.<\/span><span class=\"token function\">push<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;Y&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        stack<span class=\"token punctuation\">.<\/span><span class=\"token function\">push<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;Z&#034;<\/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>stack<span class=\"token punctuation\">.<\/span><span class=\"token function\">pop<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ Z&#xff08;\u540e\u8fdb\u5148\u51fa&#xff09;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>ArrayDeque \u5728\u4f5c\u4e3a\u961f\u5217\u6216\u6808\u4f7f\u7528\u65f6&#xff0c;\u6027\u80fd\u4f18\u4e8e LinkedList \u548c Stack&#xff0c;\u662f\u63a8\u8350\u7684\u9996\u9009\u3002<\/p>\n<h5>5.3 PriorityQueue \u2014\u2014 \u5e26\u4f18\u5148\u7ea7\u7684\u961f\u5217<\/h5>\n<p>PriorityQueue \u4e0d\u662f FIFO \u961f\u5217&#xff0c;\u800c\u662f\u4e00\u4e2a\u4f18\u5148\u961f\u5217\u2014\u2014\u5b83\u6839\u636e\u5143\u7d20\u7684\u4f18\u5148\u7ea7&#xff08;\u81ea\u7136\u987a\u5e8f\u6216\u81ea\u5b9a\u4e49\u6bd4\u8f83\u5668&#xff09;\u51b3\u5b9a\u51fa\u961f\u987a\u5e8f\u3002\u4f18\u5148\u7ea7\u6700\u9ad8\u7684\u5143\u7d20\u6700\u5148\u51fa\u961f\u3002<\/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\">PriorityQueue<\/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\">Queue<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">PriorityQueueDemo<\/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 comment\">\/\/ \u9ed8\u8ba4\u662f\u81ea\u7136\u5347\u5e8f&#xff08;\u6700\u5c0f\u5806&#xff09;<\/span><br \/>\n        <span class=\"token class-name\">Queue<\/span><span class=\"token generics\"><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">Integer<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> pq <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">PriorityQueue<\/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        pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">30<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">10<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">50<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">offer<\/span><span class=\"token punctuation\">(<\/span><span class=\"token number\">20<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u51fa\u961f\u987a\u5e8f&#xff1a;10, 20, 30, 50&#xff08;\u4ece\u5c0f\u5230\u5927&#xff09;<\/span><br \/>\n        <span class=\"token keyword\">while<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token operator\">!<\/span>pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">isEmpty<\/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\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">print<\/span><span class=\"token punctuation\">(<\/span>pq<span class=\"token punctuation\">.<\/span><span class=\"token function\">poll<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034; &#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ 10 20 30 50<\/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>PriorityQueue \u975e\u5e38\u9002\u5408\u4efb\u52a1\u8c03\u5ea6\u3001Dijkstra \u7b97\u6cd5\u3001\u6c42 Top K \u7b49\u573a\u666f\u3002<\/p>\n<hr \/>\n<h4>6. Deque \u63a5\u53e3 \u2014\u2014 \u53cc\u7aef\u961f\u5217<\/h4>\n<p>Deque \u662f Queue \u7684\u5b50\u63a5\u53e3&#xff0c;\u8868\u793a\u53cc\u7aef\u961f\u5217&#xff08;Double Ended Queue&#xff09;\u2014\u2014\u4f60\u53ef\u4ee5\u4ece\u4e24\u7aef\u6dfb\u52a0\u548c\u79fb\u9664\u5143\u7d20\u3002\u5b83\u65e2\u53ef\u4ee5\u4f5c\u4e3a\u961f\u5217\u4f7f\u7528&#xff0c;\u4e5f\u53ef\u4ee5\u4f5c\u4e3a\u6808\u4f7f\u7528\u3002<\/p>\n<p>Deque \u7684\u4e3b\u8981\u65b9\u6cd5&#xff1a;<\/p>\n<table>\n<tr>\u64cd\u4f5c\u961f\u9996&#xff08;First&#xff09;\u961f\u5c3e&#xff08;Last&#xff09;<\/tr>\n<tbody>\n<tr>\n<td>\u6dfb\u52a0<\/td>\n<td>offerFirst() \/ addFirst()<\/td>\n<td>offerLast() \/ addLast()<\/td>\n<\/tr>\n<tr>\n<td>\u53d6\u51fa\u5e76\u79fb\u9664<\/td>\n<td>pollFirst() \/ removeFirst()<\/td>\n<td>pollLast() \/ removeLast()<\/td>\n<\/tr>\n<tr>\n<td>\u67e5\u770b<\/td>\n<td>peekFirst() \/ getFirst()<\/td>\n<td>peekLast() \/ getLast()<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>LinkedList \u548c ArrayDeque \u90fd\u5b9e\u73b0\u4e86 Deque \u63a5\u53e3\u3002<\/p>\n<p><span class=\"token class-name\">Deque<\/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> deque <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ArrayDeque<\/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 \/>\ndeque<span class=\"token punctuation\">.<\/span><span class=\"token function\">offerFirst<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5934\u90e8\u5143\u7d20&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\ndeque<span class=\"token punctuation\">.<\/span><span class=\"token function\">offerLast<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u5c3e\u90e8\u5143\u7d20&#034;<\/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>deque<span class=\"token punctuation\">.<\/span><span class=\"token function\">pollFirst<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u5934\u90e8\u5143\u7d20<\/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>deque<span class=\"token punctuation\">.<\/span><span class=\"token function\">pollLast<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u5c3e\u90e8\u5143\u7d20<\/span><\/p>\n<hr \/>\n<h4>7. JDK 21 \u7684 SequencedMap<\/h4>\n<p>\u5728 JDK 21 \u4e2d&#xff0c;Map \u4f53\u7cfb\u4e5f\u8fce\u6765\u4e86\u4e00\u4e2a\u91cd\u8981\u7684\u65b0\u6210\u5458&#xff1a;SequencedMap \u63a5\u53e3\u3002\u5b83\u4e3a\u6709\u5e8f Map&#xff08;\u5982 LinkedHashMap \u548c TreeMap&#xff09;\u63d0\u4f9b\u4e86\u7edf\u4e00\u7684\u65b9\u6cd5\u6765\u8bbf\u95ee\u201c\u7b2c\u4e00\u4e2a\u201d\u548c\u201c\u6700\u540e\u4e00\u4e2a\u201d\u952e\u503c\u5bf9\u3002<\/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\">LinkedHashMap<\/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\">SequencedMap<\/span><\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p><span class=\"token keyword\">public<\/span> <span class=\"token keyword\">class<\/span> <span class=\"token class-name\">SequencedMapDemo<\/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\">SequencedMap<\/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\">LinkedHashMap<\/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        map<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u82f9\u679c&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">5<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        map<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u9999\u8549&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        map<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;\u6a58\u5b50&#034;<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">8<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u83b7\u53d6\u7b2c\u4e00\u4e2a\u548c\u6700\u540e\u4e00\u4e2a\u952e\u503c\u5bf9<\/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>map<span class=\"token punctuation\">.<\/span><span class=\"token function\">firstEntry<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u82f9\u679c&#061;5<\/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>map<span class=\"token punctuation\">.<\/span><span class=\"token function\">lastEntry<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>    <span class=\"token comment\">\/\/ \u6a58\u5b50&#061;8<\/span><\/p>\n<p>        <span class=\"token comment\">\/\/ \u53cd\u8f6c\u987a\u5e8f<\/span><br \/>\n        <span class=\"token class-name\">SequencedMap<\/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> reversed <span class=\"token operator\">&#061;<\/span> map<span class=\"token punctuation\">.<\/span><span class=\"token function\">reversed<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        reversed<span class=\"token punctuation\">.<\/span><span class=\"token function\">forEach<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">(<\/span>k<span class=\"token punctuation\">,<\/span> v<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">-&gt;<\/span> <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>k <span class=\"token operator\">&#043;<\/span> <span class=\"token string\">&#034;&#061;&#034;<\/span> <span class=\"token operator\">&#043;<\/span> v<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token comment\">\/\/ \u6a58\u5b50&#061;8, \u9999\u8549&#061;3, \u82f9\u679c&#061;5<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>SequencedMap \u4e0e SequencedCollection\u3001SequencedSet \u5171\u540c\u6784\u6210\u4e86 JDK 21 \u5bf9\u201c\u6709\u5e8f\u96c6\u5408\u201d\u7684\u7edf\u4e00\u652f\u6301\u3002<\/p>\n<hr \/>\n<h4>8. \u7efc\u5408\u793a\u4f8b \u2014\u2014 \u7528 Map \u91cd\u6784\u5b66\u751f\u7ba1\u7406\u7cfb\u7edf<\/h4>\n<p>\u6211\u4eec\u6765\u628a\u5b66\u751f\u7ba1\u7406\u7cfb\u7edf\u4e2d\u201c\u67e5\u627e\u5b66\u751f\u201d\u7684\u529f\u80fd\u7528 Map \u91cd\u6784\u4e00\u4e0b\u3002<\/p>\n<p>\u4e4b\u524d\u7684\u505a\u6cd5&#xff1a;\u7528 List \u5b58\u50a8\u5b66\u751f&#xff0c;\u67e5\u627e\u65f6\u9700\u8981\u904d\u5386\u6574\u4e2a\u5217\u8868\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u65e7\u65b9\u5f0f&#xff1a;\u904d\u5386\u67e5\u627e<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token class-name\">Student<\/span> <span class=\"token function\">findStudentById<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> id<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\">Student<\/span> s <span class=\"token operator\">:<\/span> students<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n        <span class=\"token keyword\">if<\/span> <span class=\"token punctuation\">(<\/span>s<span class=\"token punctuation\">.<\/span><span class=\"token function\">getStudentId<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">.<\/span><span class=\"token function\">equals<\/span><span class=\"token punctuation\">(<\/span>id<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n            <span class=\"token keyword\">return<\/span> s<span class=\"token punctuation\">;<\/span><br \/>\n        <span class=\"token punctuation\">}<\/span><br \/>\n    <span class=\"token punctuation\">}<\/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><\/p>\n<p>\u91cd\u6784\u540e&#xff1a;\u7528 Map&lt;String, Student&gt; \u5b58\u50a8&#xff0c;\u5b66\u53f7\u4f5c\u4e3a\u952e&#xff0c;\u5b66\u751f\u5bf9\u8c61\u4f5c\u4e3a\u503c\u3002<\/p>\n<p><span class=\"token comment\">\/\/ SchoolManager \u4e2d\u7684\u6539\u52a8<\/span><br \/>\n<span class=\"token keyword\">private<\/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\">Student<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> studentMap <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\">private<\/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\">Teacher<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> teacherMap <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\">private<\/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\">Course<\/span><span class=\"token punctuation\">&gt;<\/span><\/span> courseMap <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\">\/\/ \u6dfb\u52a0\u5b66\u751f\u65f6&#xff0c;\u540c\u65f6\u653e\u5165 Map<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">addStudent<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">Student<\/span> s<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">put<\/span><span class=\"token punctuation\">(<\/span>s<span class=\"token punctuation\">.<\/span><span class=\"token function\">getStudentId<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> s<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u67e5\u627e\u5b66\u751f \u2014\u2014 O(1) \u65f6\u95f4&#xff01;<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token class-name\">Student<\/span> <span class=\"token function\">findStudentById<\/span><span class=\"token punctuation\">(<\/span><span class=\"token class-name\">String<\/span> id<span class=\"token punctuation\">)<\/span> <span class=\"token punctuation\">{<\/span><br \/>\n    <span class=\"token keyword\">return<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">get<\/span><span class=\"token punctuation\">(<\/span>id<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p><span class=\"token comment\">\/\/ \u67e5\u770b\u6240\u6709\u5b66\u751f<\/span><br \/>\n<span class=\"token keyword\">public<\/span> <span class=\"token keyword\">void<\/span> <span class=\"token function\">listStudents<\/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\">Student<\/span> s <span class=\"token operator\">:<\/span> studentMap<span class=\"token punctuation\">.<\/span><span class=\"token function\">values<\/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\">System<\/span><span class=\"token punctuation\">.<\/span>out<span class=\"token punctuation\">.<\/span><span class=\"token function\">println<\/span><span class=\"token punctuation\">(<\/span>s<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n    <span class=\"token punctuation\">}<\/span><br \/>\n<span class=\"token punctuation\">}<\/span><\/p>\n<p>\u8fd9\u6837\u6539\u5b8c\u4e4b\u540e&#xff0c;\u67e5\u627e\u6548\u7387\u4ece O(n) \u53d8\u6210\u4e86 O(1)&#xff0c;\u800c\u4e14\u4ee3\u7801\u66f4\u7b80\u6d01\u3002Map \u7684 values() \u65b9\u6cd5\u53ef\u4ee5\u76f4\u63a5\u83b7\u53d6\u6240\u6709\u5b66\u751f\u5bf9\u8c61&#xff0c;keySet() \u53ef\u4ee5\u83b7\u53d6\u6240\u6709\u5b66\u53f7\u3002<\/p>\n<p>&#x1f4a1; \u8bbe\u8ba1\u5efa\u8bae&#xff1a;\u5728\u9700\u8981\u9891\u7e41\u6839\u636e\u67d0\u4e2a\u552f\u4e00\u6807\u8bc6\u67e5\u627e\u5bf9\u8c61\u7684\u573a\u666f\u4e2d&#xff0c;\u7528 Map \u5b58\u50a8\u662f\u6807\u914d\u505a\u6cd5\u3002\u4f60\u751a\u81f3\u53ef\u4ee5\u8ba9 students \u5217\u8868\u548c studentMap \u540c\u65f6\u5b58\u5728\u2014\u2014\u5217\u8868\u7528\u6765\u4fdd\u6301\u987a\u5e8f&#xff0c;Map \u7528\u6765\u52a0\u901f\u67e5\u627e\u3002<\/p>\n<hr \/>\n<h4>9. \u5e38\u89c1\u9677\u9631\u4e0e\u6ce8\u610f\u4e8b\u9879<\/h4>\n<p>1. \u7528\u53ef\u53d8\u5bf9\u8c61\u4f5c\u4e3a Map \u7684\u952e<\/p>\n<p>\u5982\u679c\u952e\u5bf9\u8c61\u662f\u53ef\u53d8\u7684&#xff0c;\u5e76\u4e14\u4fee\u6539\u540e\u5f71\u54cd\u4e86 hashCode() \u6216 equals() \u7684\u8fd4\u56de\u503c&#xff0c;\u90a3\u8fd9\u4e2a\u952e\u5c31\u201c\u4e22\u5931\u201d\u4e86\u2014\u2014\u4f60\u518d\u4e5f\u627e\u4e0d\u5230\u5bf9\u5e94\u7684\u503c\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u9519\u8bef\u793a\u4f8b<\/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\">List<\/span><span class=\"token punctuation\">&lt;<\/span><span class=\"token class-name\">String<\/span><span class=\"token punctuation\">&gt;<\/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\">List<\/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> key <span class=\"token operator\">&#061;<\/span> <span class=\"token keyword\">new<\/span> <span class=\"token class-name\">ArrayList<\/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 \/>\nkey<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;A&#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;value&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\nkey<span class=\"token punctuation\">.<\/span><span class=\"token function\">add<\/span><span class=\"token punctuation\">(<\/span><span class=\"token string\">&#034;B&#034;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span>   <span class=\"token comment\">\/\/ \u4fee\u6539\u4e86\u952e&#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>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 punctuation\">;<\/span>  <span class=\"token comment\">\/\/ \u53ef\u80fd\u8fd4\u56de null&#xff0c;\u56e0\u4e3a hashCode \u53d8\u4e86<\/span><\/p>\n<p>\u89e3\u51b3\u65b9\u6848&#xff1a;\u4f7f\u7528\u4e0d\u53ef\u53d8\u5bf9\u8c61\u4f5c\u4e3a\u952e&#xff08;\u5982 String\u3001Integer&#xff0c;\u6216\u8005\u4f60\u81ea\u5df1\u7684\u4e0d\u53ef\u53d8\u7c7b&#xff09;\u3002<\/p>\n<p>2. HashMap \u4e2d\u7684 null \u503c<\/p>\n<ul>\n<li>HashMap \u5141\u8bb8\u4e00\u4e2a null \u952e\u548c\u4efb\u610f\u4e2a null \u503c\u3002<\/li>\n<li>TreeMap \u4e0d\u5141\u8bb8 null \u952e&#xff08;\u56e0\u4e3a\u65e0\u6cd5\u6392\u5e8f&#xff09;&#xff0c;\u4f46\u503c\u53ef\u4ee5\u662f null\u3002<\/li>\n<li>ConcurrentHashMap \u4e0d\u5141\u8bb8 null \u952e\u6216\u503c\u3002<\/li>\n<\/ul>\n<p>3. \u904d\u5386\u65f6\u4fee\u6539 Map<\/p>\n<p>\u548c\u96c6\u5408\u4e00\u6837&#xff0c;\u5728\u904d\u5386 Map \u65f6&#xff08;\u65e0\u8bba\u662f keySet()\u3001values() \u8fd8\u662f entrySet()&#xff09;&#xff0c;\u4e0d\u80fd\u76f4\u63a5\u8c03\u7528 put() \u6216 remove()&#xff0c;\u5426\u5219\u4f1a\u629b\u51fa ConcurrentModificationException\u3002\u53ef\u4ee5\u4f7f\u7528\u8fed\u4ee3\u5668\u7684 remove() \u65b9\u6cd5&#xff0c;\u6216\u4f7f\u7528 removeIf()\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u5b89\u5168\u5220\u9664&#xff1a;\u4f7f\u7528 entrySet \u7684 removeIf<\/span><br \/>\nstudentMap<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 function\">removeIf<\/span><span class=\"token punctuation\">(<\/span>entry <span class=\"token operator\">-&gt;<\/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><span class=\"token function\">getAge<\/span><span class=\"token punctuation\">(<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">18<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<p>4. \u9009\u62e9\u5408\u9002\u7684\u521d\u59cb\u5bb9\u91cf<\/p>\n<p>\u5982\u679c\u4f60\u80fd\u9884\u4f30 Map \u7684\u5927\u5c0f&#xff0c;\u5728\u6784\u9020\u65f6\u6307\u5b9a\u521d\u59cb\u5bb9\u91cf\u53ef\u4ee5\u51cf\u5c11\u6269\u5bb9\u5f00\u9500&#xff0c;\u63d0\u5347\u6027\u80fd\u3002<\/p>\n<p><span class=\"token comment\">\/\/ \u9884\u8ba1\u5b58\u50a8 1000 \u4e2a\u5143\u7d20<\/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\">Student<\/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 number\">1000<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><\/p>\n<hr \/>\n<h4>10. \u4eca\u5929\u7684\u603b\u7ed3<\/h4>\n<p>\u4eca\u5929\u6211\u4eec\u5b66\u4e60\u4e86 Map \u548c Queue \u4e24\u4e2a\u91cd\u8981\u7684\u96c6\u5408\u7c7b\u578b&#xff1a;<\/p>\n<p>Map&#xff08;\u6620\u5c04&#xff09;<\/p>\n<ul>\n<li>\u5b58\u50a8\u952e\u503c\u5bf9&#xff0c;\u952e\u552f\u4e00\u3002\u6838\u5fc3\u5b9e\u73b0&#xff1a;HashMap&#xff08;\u6700\u5feb&#xff09;\u3001LinkedHashMap&#xff08;\u4fdd\u7559\u63d2\u5165\u987a\u5e8f&#xff09;\u3001TreeMap&#xff08;\u6309\u952e\u6392\u5e8f&#xff09;\u3002<\/li>\n<li>\u904d\u5386\u65b9\u5f0f&#xff1a;keySet()\u3001values()\u3001entrySet()&#xff08;\u6700\u5e38\u7528&#xff09;\u3002<\/li>\n<li>\u952e\u7684\u76f8\u7b49\u6027\u4f9d\u8d56 hashCode() \u548c equals()&#xff0c;\u81ea\u5b9a\u4e49\u952e\u5fc5\u987b\u91cd\u5199\u3002<\/li>\n<li>JDK 21 \u65b0\u589e SequencedMap&#xff0c;\u652f\u6301\u6709\u5e8f\u8bbf\u95ee\u3002<\/li>\n<\/ul>\n<p>Queue&#xff08;\u961f\u5217&#xff09;<\/p>\n<ul>\n<li>FIFO \u6570\u636e\u7ed3\u6784&#xff0c;\u6838\u5fc3\u5b9e\u73b0&#xff1a;LinkedList\u3001ArrayDeque&#xff08;\u63a8\u8350&#xff09;\u3001PriorityQueue&#xff08;\u6309\u4f18\u5148\u7ea7\u51fa\u961f&#xff09;\u3002<\/li>\n<li>Deque \u53cc\u7aef\u961f\u5217&#xff0c;\u53ef\u4f5c\u4e3a\u961f\u5217\u6216\u6808\u4f7f\u7528\u3002<\/li>\n<li>\u63a8\u8350\u4f7f\u7528 offer()\u3001poll()\u3001peek() \u7cfb\u5217\u65b9\u6cd5&#xff0c;\u5b83\u4eec\u5728\u961f\u5217\u7a7a\u65f6\u8fd4\u56de null \u800c\u975e\u629b\u5f02\u5e38\u3002<\/li>\n<\/ul>\n<p>Map \u548c Queue \u662f\u65e5\u5e38\u5f00\u53d1\u4e2d\u4f7f\u7528\u9891\u7387\u6781\u9ad8\u7684\u6570\u636e\u7ed3\u6784\u3002\u638c\u63e1\u5b83\u4eec&#xff0c;\u4f60\u5c31\u80fd\u4f18\u96c5\u5730\u5904\u7406\u201c\u6620\u5c04\u5173\u7cfb\u201d\u548c\u201c\u6392\u961f\u4efb\u52a1\u201d\u8fd9\u4e24\u7c7b\u5e38\u89c1\u573a\u666f\u3002<\/p>\n<hr \/>\n<h4>\u52a8\u624b\u8bd5\u8bd5<\/h4>\n<li>\u521b\u5efa\u4e00\u4e2a HashMap&lt;String, 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