<p>As a general rule, the default load factor (.75) offers a good\ntradeoff between time and space costs. Higher values decrease the\nspace overhead but increase the lookup cost (reflected in most of\nthe operations of the <tt>HashMap<\/tt> class, including\n<tt>get<\/tt> and <tt>put<\/tt>). The expected number of entries in\nthe map and its load factor should be taken into account when\nsetting its initial capacity, so as to minimize the number of\nrehash operations. If the initial capacity is greater than the\nmaximum number of entries divided by the load factor, no rehash\noperations will ever occur.<\/code><\/pre>\n\u5927\u6982\u610f\u601d\u5c31\u662f\uff1a\u52a0\u8f7d\u56e0\u5b50\u592a\u5c0f\u6d6a\u8d39\u7a7a\u95f4\u4e14\u4f1a\u53d1\u751f\u66f4\u591a\u6b21\u6570\u7684rehash\uff0c\u592a\u5927\u7684\u8bdd\u4f1a\u589e\u52a0hash\u51b2\u7a81\uff0c\u6240\u4ee50.75\u662f\u4e00\u4e2a\u6298\u4e2d\u7684\u9009\u62e9\u3002<\/p>\n
(4).TREEIFY_THRESHOLD(\u94fe\u8868\u8f6c\u4e3a\u7ea2\u9ed1\u6811\u9608\u503c)<\/h5>\n\u2460.\u4e3a\u4ec0\u4e48Map\u6876\u4e2d\u4e2a\u6570\u8d85\u8fc78\u624d\u8f6c\u4e3a\u7ea2\u9ed1\u6811<\/h6>\n
\u6e90\u7801\u4e2d\u4e5f\u7ed9\u51fa\u4e86\u89e3\u91ca<\/p>\n
Because TreeNodes are about twice the size of regular nodes, we\nuse them only when bins contain enough nodes to warrant use\n(see TREEIFY_THRESHOLD). And when they become too small (due to\nremoval or resizing) they are converted back to plain bins. In\nusages with well-distributed user hashCodes, tree bins are\nrarely used. Ideally, under random hashCodes, the frequency of\nnodes in bins follows a Poisson distribution\n(http:\/\/en.wikipedia.org\/wiki\/Poisson_distribution) with a\nparameter of about 0.5 on average for the default resizing\nthreshold of 0.75, although with a large variance because of\nresizing granularity. Ignoring variance, the expected\noccurrences of list size k are (exp(-0.5) * pow(0.5, k) \/\nfactorial(k)). The first values are:\n0: 0.60653066\n1: 0.30326533\n2: 0.07581633\n3: 0.01263606\n4: 0.00157952\n5: 0.00015795\n6: 0.00001316\n7: 0.00000094\n8: 0.00000006\nmore: less than 1 in ten million<\/code><\/pre>\n\u8fd9\u6bb5\u5185\u5bb9\u8bf4\u5230\uff0chashcode\u79bb\u6563\u6027\u5f88\u597d\u7684\u65f6\u5019\uff0c\u6811\u578bbin\u7528\u5230\u7684\u6982\u7387\u975e\u5e38\u5c0f\uff0c\u56e0\u4e3a\u6570\u636e\u5747\u5300\u5206\u5e03\u5728\u6bcf\u4e2abin\u4e2d\uff0c\u51e0\u4e4e\u4e0d\u4f1a\u6709bin\u4e2d\u94fe\u8868\u957f\u5ea6\u4f1a\u8fbe\u5230\u9608\u503c\u3002
\n\u4f46\u662f\u5728\u968f\u673ahashcode\u4e0b\uff0c\u79bb\u6563\u6027\u53ef\u80fd\u4f1a\u53d8\u5dee\uff0c\u800cJDK\u53c8\u4e0d\u80fd\u963b\u6b62\u7528\u6237\u5b9e\u73b0\u8fd9\u79cd\u4e0d\u597d\u7684hash\u7b97\u6cd5\uff0c\u56e0\u6b64\u53ef\u80fd\u5bfc\u81f4\u4e0d\u5747\u5300\u7684\u6570\u636e\u5206\u5e03\u3002
\n\u4e0d\u8fc7\u7406\u60f3\u60c5\u51b5\u4e0b\uff0c\u968f\u673a\u7684hashcode\u7b97\u6cd5\u4e0b\u6240\u6709\u7684bin\u4e2d\u7684\u7ed3\u70b9\u5206\u5e03\u9891\u7387\u4f1a\u9075\u5faa\u6cca\u677e\u5206\u5e03\uff0c\u6ce8\u91ca\u4e2d\u4e5f\u5217\u51fa\u6765\u4e86\uff0c\u94fe\u8868\u957f\u5ea6\u5230\u8fbe8\u7684\u6982\u7387\u4e3a0.00000006\uff0c\u51e0\u4e4e\u662f\u4e0d\u53ef\u80fd\u4e8b\u4ef6\uff0c\u6240\u4ee5\u624d\u9009\u62e98\u4f5c\u4e3a\u9608\u503c\u3002<\/p>\n
(5).UNTREEIFY_THRESHOLD(\u7ea2\u9ed1\u6811\u8f6c\u4e3a\u94fe\u8868\u9608\u503c)<\/h5>\n\u2460.\u4e3a\u4ec0\u4e48\u9608\u503c\u4e3a6<\/h6>\n
\u5982\u679c\u9608\u503c\u4e3a7\uff0c\u5f53\u6211\u4eec\u9891\u7e41\u7684\u6dfb\u52a0\u548c\u5220\u9664\u64cd\u4f5c\u65f6\uff0c\u4f1a\u9020\u6210\u7ea2\u9ed1\u6811\u548c\u94fe\u8868\u7684\u9891\u7e41\u8f6c\u6362\uff0c\u5f71\u54cd\u6027\u80fd\u3002<\/p>\n
(6).MIN_TREEIFY_CAPACITY(\u6700\u5c0f\u6811\u578b\u5316\u9608\u503c)<\/h5>\n\u2460.\u4f5c\u7528<\/h6>\n
\u5f53\u6570\u7ec4\u4e2d\u7ed3\u70b9\u5927\u4e8eTREEIFY_THRESHOLD<\/strong>\uff0c\u4f46\u662f\u6574\u4e2a\u54c8\u5e0c\u8868\u7684\u5bb9\u91cf\u5c0f\u4e8eMIN_TREEIFY_CAPACITY<\/strong>\u65f6\uff0c\u53ea\u4f1a\u6269\u5bb9\uff0c\u4e0d\u4f1a\u53d8\u6210\u7ea2\u9ed1\u6811\uff0c\u53ea\u6709\u5728\u54c8\u5e0c\u8868\u7684\u5bb9\u91cf\u5927\u4e8eMIN_TREEIFY_CAPACITY<\/strong>\u5e76\u4e14\u6570\u7ec4\u4e2d\u7ed3\u70b9\u5927\u4e8eTREEIFY_THRESHOLD<\/strong>\u65f6\uff0c\u624d\u4f1a\u8f6c\u4e3a\u7ea2\u9ed1\u6811\u3002<\/p>\n\u2461.\u4e3a\u4ec0\u4e48\u53d664<\/h6>\nThe smallest table capacity for which bins may be treeified.\n(Otherwise the table is resized if too many nodes in a bin.)\nShould be at least 4 * TREEIFY_THRESHOLD to avoid conflicts\nbetween resizing and treeification thresholds.<\/code><\/pre>\n\u6ce8\u91ca\u4e2d\u6709\u63d0\u5230\uff0cMIN_TREEIFY_CAPACITY\u7684\u503c\u81f3\u5c11\u662fTREEIFY_THRESHOLD\u76844\u500d\uff0c\u4f46\u662f\u8f6c\u4e3a\u7ea2\u9ed1\u6811\u7684\u9608\u503c\u662f8\uff0c\u4e5f\u5c31\u8bf4MIN_TREEIFY_CAPACITY\u7684\u503c\u6700\u5c11\u5e94\u8be5\u4e3a32\uff0c\u8fd9\u91cc\u8bbe\u7f6e\u621064\u7684\u539f\u56e0\u53ef\u80fd\u662f\u7b49\u5230\u6570\u7ec4\u6269\u5bb9\u5230\u4e8632\u540e\u518d\u6269\u5bb9\u4e00\u6b21\u540e\u624d\u4f1a\u5f00\u59cb\u89e6\u53d1\u6811\u578b\u5316\u3002<\/p>\n
4.\u6784\u9020\u5668<\/h4>\n
HashMap\u4e00\u5171\u67094\u4e2a\u6784\u9020\u5668\u3002<\/p>\n
(1).\u5e38\u7528\u6784\u9020\u5668<\/h5>\n
\u4f7f\u7528\u8be5\u6784\u9020\u5668\u5982\u679c\u7528\u6237\u6ca1\u6709\u4f20\u5165initialCapacity \u548cloadFactor\u8fd9\u4e24\u4e2a\u53c2\u6570\uff0c\u4f1a\u4f7f\u7528\u9ed8\u8ba4\u503c\u3002
\ninitialCapacity\u9ed8\u8ba4\u4e3a16\uff0cloadFactory\u9ed8\u8ba4\u4e3a0.75<\/p>\n
public HashMap(int initialCapacity, float loadFactor) {\n if (initialCapacity < 0)\n throw new IllegalArgumentException("Illegal initial capacity: " +initialCapacity);\n if (initialCapacity > MAXIMUM_CAPACITY)\n \/\/\u5982\u679c\u6307\u5b9a\u7684\u957f\u5ea6\u5927\u4e8e\u4e86\u6700\u5927\u6570\u7ec4\u5bb9\u91cf\uff0c\u90a3\u5c31\u4f1a\u4f7f\u7528\u6700\u5927\u6570\u7ec4\u5bb9\u91cf\u4f5c\u4e3a\u5bb9\u91cf\n initialCapacity = MAXIMUM_CAPACITY;\n if (loadFactor <= 0 || Float.isNaN(loadFactor))\n throw new IllegalArgumentException("Illegal load factor: " +loadFactor);\n this.loadFactor = loadFactor;\n \/\/\u521d\u59cb\u5316\u5bb9\u91cf\u4e5f\u4f1a\u6839\u636e\u4f20\u5165\u7684\u503c\uff0c\u9009\u53d6\u4e00\u4e2a\u5927\u4e8e\u7b49\u4e8e\u4f20\u5165\u503c\u76842\u7684n\u6b21\u5e42\u7684\u6570\u66ff\u4ee3\n this.threshold = tableSizeFor(initialCapacity);\n }<\/code><\/pre>\n(2).\u6307\u5b9a\u5bb9\u91cf\u7684\u6784\u9020\u5668<\/h5>\n
\u53ef\u4ee5\u6307\u5b9a\u957f\u5ea6\uff0c\u52a0\u8f7d\u56e0\u5b50\u4f7f\u7528\u9ed8\u8ba4\u76840.75\uff1b<\/p>\n
public HashMap(int initialCapacity) {\n this(initialCapacity, DEFAULT_LOAD_FACTOR);\n }<\/code><\/pre>\n(3).\u91c7\u7528\u9ed8\u8ba4\u53c2\u6570\u7684\u6784\u9020\u5668<\/h5>\npublic HashMap() {\n this.loadFactor = DEFAULT_LOAD_FACTOR; \/\/ all other fields defaulted\n }<\/code><\/pre>\n(4).\u62f7\u8d1d\u6784\u9020\u5668<\/h5>\npublic HashMap(Map<? extends K, ? extends V> m) {\n this.loadFactor = DEFAULT_LOAD_FACTOR;\n putMapEntries(m, false);\n }<\/code><\/pre>\n5.\u5185\u90e8\u65b9\u6cd5<\/h4>\n(1).putMapEntries\u65b9\u6cd5<\/h5>\nfinal void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {\n int s = m.size();\n \/\/\u4f20\u5165\u7684map\u5927\u5c0f\u4e0d\u80fd\u662f0\n if (s > 0) {\n \/\/\u5982\u679c\u8fd8\u6ca1\u6709\u5b58\u50a8\u8fc7\u4efb\u4f55\u5143\u7d20\uff0c\u624d\u80fd\u8fdb\u5165\uff0c\u5982\u679c\u5df2\u7ecf\u5b58\u50a8\u8fc7\u5143\u7d20\u4f1a\u76f4\u63a5\u89e6\u53d1resize\n if (table == null) { \/\/ pre-size\n \/*\n \u5148\u4e0d\u8003\u8651\u5bb9\u91cf\u662f\u5426\u4e3a2\u7684\u5e42\uff0c\u5148\u7b97\u51fa\u5bb9\u5668\u7684\u5bb9\u91cf\n \u56e0\u4e3a\u8f6c\u4e3a\u4e86float\uff0c\u7b97\u51fa\u6765\u7684\u6570\u4f1a\u6709\u5c0f\u6570\uff0c\u76f4\u63a5\u4e0a\u53d6\u6574\uff0c\u6240\u4ee5\u505a\u4e86\u4e2a+1\u7684\u64cd\u4f5c\n *\/\n float ft = ((float)s \/ loadFactor) + 1.0F;\n \/*\n \u5982\u679c\u5c0f\u4e8e\u6700\u5927\u5bb9\u91cf\uff0c\u90a3\u4e48\u76f4\u63a5\u5c06\u8be5\u503c\u53d6\u4e3a\u6574\u578b\uff0c\u7136\u540e\u4f7f\u7528\n \u5982\u679c\u5927\u4e8e\u6700\u5927\u5bb9\u91cf\uff0c\u5c31\u8d4b\u503c\u4e3a\u6700\u5927\u5bb9\u91cf\n *\/\n int t = ((ft < (float)MAXIMUM_CAPACITY) ?\n (int)ft : MAXIMUM_CAPACITY);\n \/*\n \u4e0a\u9762\u7684\u64cd\u4f5c\u5df2\u7ecf\u786e\u5b9a\u597d\u4e86\u5bb9\u91cf\u7684\u5927\u6982\u6570\u503c\n \u56e0\u4e3a\u5bb9\u91cf\u8981\u6c42\u662f2\u7684\u6b21\u5e42\uff0c\u8fd9\u91cc\u518d\u6839\u636e\u521a\u521a\u5f97\u5230\u7684\u5927\u5c0f\uff0c\n \u627e\u5230\u4e00\u4e2a\u5927\u4e8e\u7b49\u4e8e\u8fd9\u4e2a\u5bb9\u91cf\u76842\u6b21\u5e42\u4f5c\u4e3a\u771f\u6b63\u7684\u5bb9\u91cf\n *\/\n if (t > threshold)\n threshold = tableSizeFor(t);\n }\n \/*\n \u5982\u679c\u80fd\u5230\u8fd9\u91cc\uff0c\u8bf4\u660e\u5df2\u7ecf\u521d\u59cb\u5316\u8fc7\u4e86\uff0c\n \u8fd9\u91cc\u5224\u65ad\u4f20\u5165\u7684map\u5927\u5c0f\uff0c\u662f\u5426\u5df2\u7ecf\u5927\u4e8e\u5f53\u524d\u5b58\u50a8\u7684\u6700\u5927\u503c\u4e86\n *\/\n else if (s > threshold)\n \/\/\u5982\u679c\u4f20\u5165map\u7684\u5927\u5c0f\u5927\u4e8e\u4e86\u5b58\u50a8\u6700\u5927\u503c\uff0c\u90a3\u4e48\u5fc5\u987b\u5148\u8fdb\u884c\u6269\u5bb9\n resize();\n \/\/\u5faa\u73af\u8c03\u7528putVal\u5b58\u5165\u5143\u7d20\uff0cputVal\u65b9\u6cd5\u91cc\u9762\u4e5f\u53ef\u4ee5\u8fdb\u884c\u6269\u5bb9\n for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {\n K key = e.getKey();\n V value = e.getValue();\n putVal(hash(key), key, value, false, evict);\n }\n }\n }<\/code><\/pre>\n\u603b\u7ed3\uff1a<\/p>\n
\n- \u5982\u679c\u5f53\u524d\u7684HashMap\u662f\u7a7a\u7684\uff0c\u90a3\u4e48\u4f1a\u5148\u786e\u5b9a\u63d2\u5165\u540eHashMap\u7684\u5bb9\u91cf<\/li>\n
- \u5982\u679c\u5f53\u524d\u7684HashMap\u4e0d\u662f\u7a7a\u7684\uff0c\u4f1a\u5148\u5224\u65ad\u662f\u5426\u9700\u8981resize<\/li>\n
- \u63d2\u5165\u5143\u7d20\u5c31\u662f\u83b7\u53d6\u5230\u6240\u6709\u7684key-value\u5faa\u73af\u8c03\u7528putVal\u65b9\u6cd5<\/li>\n<\/ol>\n
(2).putVal\u65b9\u6cd5<\/h5>\nfinal V putVal(int hash, K key, V value, boolean onlyIfAbsent,\n boolean evict) {\n \/*\n tab\u662f\u5f53\u524dHashMap\u7684\u6570\u7ec4\n p\u662f\u8981\u64cd\u4f5c\u7684Node\n n\u662f\u5f53\u524dHashMap\u7684Node\u6570\u7ec4\u957f\u5ea6\n i\u662f\u64cd\u4f5c\u7684\u6570\u7ec4\u4e0b\u6807\n *\/\n Node<K,V>[] tab; Node<K,V> p; int n, i;\n \/*\n \u8fd9\u91cc\u7684\u64cd\u4f5c\u662f\u5224\u65adHashMap\u662f\u5426\u662f\u7a7a\u7684\n \u540c\u65f6\uff0c\u628aHashMap\u7684table\u8d4b\u503c\u7ed9\u4e86tab\n \u5c06HashMap\u7684\u957f\u5ea6\u8d4b\u503c\u7ed9\u4e86n\n *\/\n if ((tab = table) == null || (n = tab.length) == 0)\n \/\/\u8c03\u7528resize\uff0c\u751f\u6210\u4e86\u4e00\u4e2atab\u6570\u7ec4\uff0c\u5e76\u4e14\u83b7\u53d6\u4e86\u4ed6\u7684\u957f\u5ea6\n n = (tab = resize()).length;\n \/*\n (n-1)&hash \u5176\u5b9e\u5c31\u662f\u4e00\u4e2a\u53d6\u6a21\u8fd0\u7b97\u76f8\u5f53\u4e8ehash%n\n \u6839\u636ehash\u627e\u5230\u6570\u7ec4\u4e2d\u7684\u7d22\u5f15\u4f4d\u7f6e\n *\/\n if ((p = tab[i = (n - 1) & hash]) == null)\n \/*\n \u5f53\u6570\u7ec4\u4e2d\u5f53\u524d\u4f4d\u7f6e\u6ca1\u6709\u5143\u7d20\u7684\u65f6\u5019\n \u4f1a\u5728\u8fd9\u4e2a\u4f4d\u7f6e\u5b9e\u4f8b\u5316\u4e00\u4e2a\u5143\u7d20\u4f5c\u4e3a\u8fd9\u4e2a\u4f4d\u7f6e\u4e2d\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\n *\/\n tab[i] = newNode(hash, key, value, null);\n else {\n \/\/\u8fdb\u5165\u5230\u8fd9\u91cc\u8bf4\u660e\u6570\u7ec4\u4e2d\u6709\u5143\u7d20\u4e86\uff0c\u9700\u8981\u5904\u7406hash\u51b2\u7a81\n Node<K,V> e; K k;\n \/\/\u5982\u679c\u6570\u7ec4\u4e2d\u5f53\u524d\u4f4d\u7f6e\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u7684key\u4e0e\u65b0\u63d2\u5165\u7684\u5143\u7d20\u7684key\u76f8\u540c\n if (p.hash == hash &&\n ((k = p.key) == key || (key != null && key.equals(k))))\n \/\/\u5c06e\u6307\u5411p\n e = p;\n else if (p instanceof TreeNode)\n \/\/\u5982\u679c\u5df2\u7ecf\u6811\u5316\uff0c\u8c03\u7528putTreeVal\u63d2\u5165\u65b9\u6cd5\u63d2\u5165\n e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);\n \/\/\u5982\u679c\u8fd8\u6ca1\u6709\u88ab\u6811\u5316\uff0c\u8fd8\u662f\u94fe\u8868\n else {\n for (int binCount = 0; ; ++binCount) {\n \/*\n \u904d\u5386\u5230\u94fe\u8868\u5c3e\u90e8\uff0c\u5982\u679c\u6ca1\u6709\u53d1\u73b0\u76f8\u540c\u7684key\u7ed3\u70b9\uff0c\u91c7\u7528\u5c3e\u63d2\u6cd5\u63d2\u5165\u5143\u7d20\n \u56e0\u4e3a\u63d2\u5165\u4e86\u4e00\u4e2a\u65b0\u7684\u5143\u7d20\uff0c\u6240\u4ee5\u8981\u5224\u65ad\u4e00\u4e0b\u5f53\u524d\u94fe\u8868\u7684\u957f\u5ea6\n \u5982\u679c\u8d85\u8fc7\u9608\u503c\uff0c\u5c31\u4f1a\u8f6c\u4e3a\u7ea2\u9ed1\u6811\n *\/\n if ((e = p.next) == null) {\n p.next = newNode(hash, key, value, null);\n if (binCount >= TREEIFY_THRESHOLD - 1) \/\/ -1 for 1st\n treeifyBin(tab, hash);\n break;\n }\n \/\/\u5982\u679c\u6570\u7ec4\u4e2d\u6709\u5143\u7d20\u7684key\u4e0e\u65b0\u63d2\u5165\u7684key\u5b8c\u5168\u76f8\u540c\uff0c\u7528e\u6307\u5411p\n if (e.hash == hash &&((k = e.key) == key || (key != null && key.equals(k))))\n break;\n p = e;\n }\n }\n \/*\n \u901a\u8fc7\u4e0a\u9762\u7684\u64cd\u4f5c\uff0c\u5982\u679cmap\u4e2d\u6709\u76f8\u540c\u7684key\n \u6211\u4eec\u5c06e\u6307\u5411\u8be5\u7ed3\u70b9\n \u5982\u679ce\u662f\u7a7a\u7684\uff0c\u8bf4\u660e\u6210\u529f\u63d2\u5165\u4e86\n \u5982\u679ce\u4e0d\u662f\u7a7a\u7684\uff0c\u5c31\u628ae\u7684value\u6700\u4e3a\u65e7\u503c\u8fd4\u56de\uff0c\u5c06\u65b0\u63d2\u5165\u7684value\u4fdd\u5b58\u8fdb\u53bb\n *\/\n if (e != null) { \/\/ existing mapping for key\n V oldValue = e.value;\n if (!onlyIfAbsent || oldValue == null)\n e.value = value;\n \/\/hashmap\u7684afterNodeAccess\u662f\u4e2a\u7a7a\u51fd\u6570\uff0cLinkedHashMap\u5b9e\u73b0\u4e86\u4ed6\n afterNodeAccess(e);\n return oldValue;\n }\n }\n \/\/\u64cd\u4f5c\u6b21\u6570++\n ++modCount;\n \/\/\u63d2\u5165\u540esize\u4f1a+1\uff0c\u5e76\u4e14\u5224\u65ad\u6570\u7ec4\u957f\u5ea6\uff0c\u662f\u5426\u9700\u8981resize\n if (++size > threshold)\n resize();\n afterNodeInsertion(evict);\n return null;\n }<\/code><\/pre>\n\u603b\u7ed3\uff1a<\/p>\n
\n- \u5982\u679c\u5f53\u524d\u7684HashMap\u662f\u7a7a\u7684\uff0c\u4f1a\u8fdb\u884c\u4e00\u6b21resize<\/li>\n
- \u5982\u679c\u4e24\u4e2akey\u76f8\u540c\uff0c\u4f1a\u7528\u65b0\u503c\u8986\u76d6\u65e7\u503c<\/li>\n
- \u65b0\u589e\u5143\u7d20\u5728\u94fe\u8868\u4e2d\u91c7\u7528\u7684\u662f\u5c3e\u63d2\u6cd5<\/li>\n
- \u5728\u65b0\u589e\u4e86\u4e00\u4e2a\u5143\u7d20\u540e\uff0c\u90fd\u4f1a\u901a\u8fc7size\u8fdb\u884c\u4e00\u6b21resize\u5224\u65ad<\/li>\n<\/ol>\n
(3).resize\u65b9\u6cd5<\/h5>\nfinal Node<K,V>[] resize() {\n \/\/\u9996\u5148\u4fdd\u5b58\u65e7\u7684\u6570\u7ec4\n Node<K,V>[] oldTab = table;\n \/\/\u83b7\u53d6\u65e7\u6570\u7ec4\u7684\u957f\u5ea6\uff0c\u5982\u679c\u662f\u7a7a\u7684\u5c31\u4e3a0\n int oldCap = (oldTab == null) ? 0 : oldTab.length;\n \/\/\u83b7\u53d6\u6269\u5bb9\u524dHashMap\u7684\u5bb9\u91cf\n int oldThr = threshold;\n \/*\n newCap\uff1a\u65b0\u6570\u7ec4\u7684\u957f\u5ea6\n newThr\uff1a\u65b0HashMap\u7684\u6700\u5927\u5bb9\u91cf\n *\/\n int newCap, newThr = 0;\n \/\/\u5224\u65ad\u65e7HashMap\u662f\u5426\u5b58\u5165\u4e86\u5143\u7d20\n if (oldCap > 0) {\n \/\/\u65e7\u6570\u7ec4\u7684\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e\u6700\u5927\u5bb9\u91cf\uff0c\u9608\u503c\u5c31\u4f1a\u8bbe\u7f6e\u4e3aInteger\u7684\u6700\u5927\u503c\n if (oldCap >= MAXIMUM_CAPACITY) {\n threshold = Integer.MAX_VALUE;\n return oldTab;\n }\n \/*\n \u9996\u5148\uff0c\u65b0\u5bb9\u91cf\u4f1a\u8bbe\u7f6e\u4e3a\u65e7\u5bb9\u91cf\u7684\u4e24\u500d\n \u7136\u540e\uff0c\u5224\u65ad\u6269\u5bb9\u540e\u7684\u65b0\u5bb9\u91cf\u662f\u5426<2^30\n \u5e76\u4e14\u65e7\u5bb9\u91cf\u662f\u5426>=16\n *\/\n else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&\n oldCap >= DEFAULT_INITIAL_CAPACITY)\n \/\/\u4ee5\u4e0a\u6761\u4ef6\u90fd\u6ee1\u8db3\u7684\u8bdd\uff0c\u9608\u503c\u4e5f\u4f1a\u7ffb\u500d\n newThr = oldThr << 1; \/\/ double threshold\n }\n else if (oldThr > 0) \/\/ initial capacity was placed in threshold\n newCap = oldThr;\n else { \/\/ zero initial threshold signifies using defaults\n newCap = DEFAULT_INITIAL_CAPACITY;\n newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);\n }\n if (newThr == 0) {\n float ft = (float)newCap * loadFactor;\n newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?\n (int)ft : Integer.MAX_VALUE);\n }\n threshold = newThr;\n @SuppressWarnings({"rawtypes","unchecked"})\n \/*\n \u901a\u8fc7\u4e0a\u9762\u7684\u64cd\u4f5c\uff0c\u5df2\u7ecf\u786e\u5b9a\u597d\u4e86\u5bb9\u91cf\u548c\u6269\u5bb9\u9608\u503c\n 1.\u5982\u679c\u6269\u5bb9\u524d\u7684HashMap\u6ca1\u6709\u5b58\u5165\u5143\u7d20\uff0c\u5c31\u6309\u7167\u9ed8\u8ba4\u503c\u8fdb\u884c\u6269\u5bb9\n 2.\u5982\u679c\u6269\u5bb9\u524d\u7684HashMap\u5df2\u7ecf\u5b58\u5165\u4e86\u5143\u7d20\uff0c\u76f4\u63a5\u6269\u5bb9\u4e24\u500d\uff0c\u5982\u679c\u65e7\u6570\u7ec4\u7684\u957f\u5ea6\u5927\u4e8e\u4e8616\uff0c\u90a3\u4e48threshold\u4e5f\u6269\u5927\u4e24\u500d\n 3.\u5982\u679c\u6b64\u65f6\u7684\u6570\u7ec4\u957f\u5ea6\u5df2\u7ecf\u5230\u4e86HashMap\u7684\u6700\u5927\u5bb9\u91cf\u65f6\uff0c\u4f1a\u5c06threshol\u8bbe\u7f6e\u4e3aInteger\u7684\u6700\u5927\u503c\n *\/\n Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];\n table = newTab;\n if (oldTab != null) {\n for (int j = 0; j < oldCap; ++j) {\n Node<K,V> e;\n \/\/\u5c06\u539f\u6765map\u4e2d\u4e0d\u662fnull\u7684\u5143\u7d20rehash\u540e\u518d\u653e\u5230\u65b0\u7684\u6570\u7ec4\u4e2d\n if ((e = oldTab[j]) != null) {\n oldTab[j] = null;\n \/\/\u5982\u679c\u5f53\u524d\u4f4d\u7f6e\u5c31\u4e00\u4e2a\u5143\u7d20\uff0c\u90a3\u4e48\u76f4\u63a5\u653e\u5230\u65b0\u6570\u7ec4\u91cc\u9762\n if (e.next == null)\n newTab[e.hash & (newCap - 1)] = e;\n \/*\n \u8fd9\u91cc\u8868\u793a\u8fd9\u4e2a\u4f4d\u7f6e\u4e0d\u6b62\u4e00\u4e2a\u7ed3\u70b9\n \u5224\u65ad\u8fd9\u4e2a\u7ed3\u70b9\u662f\u5426\u5df2\u7ecf\u6811\u578b\u5316\u4e86\n \u5982\u679c\u5df2\u7ecf\u6811\u578b\u5316\uff0c\u5c06\u8fd9\u4e2a\u6811\u4e0a\u7684\u7ed3\u70b9rehash\u540e\u5b58\u5165\n *\/\n else if (e instanceof TreeNode)\n ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);\n else { \/\/ preserve order\n Node<K,V> loHead = null, loTail = null;\n Node<K,V> hiHead = null, hiTail = null;\n Node<K,V> next;\n do {\n next = e.next;\n \/*\n \u5982\u679c\u662ftrue,\u8868\u793a(e.hash&(newCap-1))\u8fd8\u4f1a\u548c(e.hash&(oldCap-1))\u4e00\u6837\n \u56e0\u4e3a\u65b0\u5bb9\u91cf\u662f\u65e7\u5bb9\u91cf\u7684\u4e24\u500d\uff0c\u800c\u5bb9\u91cf\u90fd\u662f2\u7684\u6b21\u5e42\n \u6240\u4ee5\u8bf4\u65b0\u5bb9\u91cf\u5c31\u662f\u65e7\u5bb9\u91cf\u7684\u4e8c\u8fdb\u5236\u4f4d\u9ad8\u4f4d\u5de6\u79fb\u4e86\u4e00\u4f4d\n \u90a3(e.hash & oldCap) == 0 \u5c31\u4ee3\u8868(e.hash & (newCap-1)) = (e.hash & (oldCap-1))\n \u8fd9\u5c31\u610f\u5473\u7740\u8be5\u5143\u7d20\u5728\u65b0\u6570\u7ec4\u4e2d\u7684\u4f4d\u7f6e\u4e0d\u4f1a\u53d8\uff0c\u56e0\u6b64\uff0c\u5c06\u5176\u7ec4\u6210\u4e00\u4e2a\u94fe\u8868\u5373\u53ef\n *\/\n if ((e.hash & oldCap) == 0) {\n if (loTail == null)\n loHead = e;\n else\n loTail.next = e;\n loTail = e;\n }\n \/*\n \u800c\u5bf9\u4e8e\u975e0\u7684key\uff0c\u90a3\u4ed6\u7684\u4f4d\u7f6e\u5728\u65b0\u6570\u7ec4\u4e2d\u9700\u8981\u66f4\u65b0\uff0c\u5c31\u9700\u8981\u5728\u65b0\u7684\u4f4d\u7f6e\u518d\u7ec4\u5408\u94fe\u8868\n *\/\n else {\n if (hiTail == null)\n hiHead = e;\n else\n hiTail.next = e;\n hiTail = e;\n }\n } while ((e = next) != null);\n if (loTail != null) {\n \/\/\u4e0d\u9700\u8981\u4fee\u6539\u7ed3\u70b9\u4f4d\u7f6e\uff0c\u76f4\u63a5\u4fdd\u5b58\u5373\u53ef\n loTail.next = null;\n newTab[j] = loHead;\n }\n if (hiTail != null) {\n hiTail.next = null;\n \/\/\u9700\u8981\u91cd\u65b0\u8ba1\u7b97\u4f4d\u7f6e\uff0c\u518d\u4fdd\u5b58\n newTab[j + oldCap] = hiHead;\n }\n }\n }\n }\n }\n return newTab;\n }<\/code><\/pre>\n(4).put\u65b9\u6cd5<\/h5>\n
HashMap\u7684put\u65b9\u6cd5\u5b9e\u73b0\u4e86Map\u7684put\u63a5\u53e3\uff0c\u5176\u5b9e\u73b0\u4e5f\u662f\u8c03\u7528\u7684HashMap\u7684putVal\u65b9\u6cd5<\/p>\n
public V put(K key, V value) {\n return putVal(hash(key), key, value, false, true);\n }<\/code><\/pre>\n(5).containsKey\u65b9\u6cd5<\/h5>\n
\u6b64\u65b9\u6cd5\u7528\u6765\u5224\u65adkey\u662f\u5426\u5b58\u5728\uff0c\u5728\u67e5\u627e\u524d\u5fc5\u987b\u6ee1\u8db3\u4e09\u4e2a\u6761\u4ef6<\/p>\n
\n- (tab=table)!=null \u6570\u7ec4\u4e0d\u80fd\u4e3a\u7a7a<\/li>\n
- (n=tab.length)>0 \u6570\u7ec4\u957f\u5ea6\u5927\u4e8e0<\/li>\n
- \uff08first = tab[(n-1)&hash]\uff09!=null \u5934\u7ed3\u70b9\u4e0d\u4e3a\u7a7a<\/li>\n<\/ol>\n
\u53ea\u6709\u4ee5\u4e0a\u4e09\u4e2a\u6761\u4ef6\u90fd\u6ee1\u8db3\u4e86\u624d\u53ef\u80fd\u5b58\u5728\u5f85\u67e5\u627e\u7684\u5143\u7d20\uff0c\u5426\u5219\u8fd4\u56denull<\/p>\n
public boolean containsKey(Object key) {\n return getNode(hash(key), key) != null;\n }\n\nfinal Node<K,V> getNode(int hash, Object key) {\n Node<K,V>[] tab; Node<K,V> first, e; int n; K k;\n if ((tab = table) != null && (n = tab.length) > 0 &&\n (first = tab[(n - 1) & hash]) != null) {\n if (first.hash == hash && \/\/ always check first node\n ((k = first.key) == key || (key != null && key.equals(k))))\n return first;\n if ((e = first.next) != null) {\n if (first instanceof TreeNode)\n return ((TreeNode<K,V>)first).getTreeNode(hash, key);\n do {\n if (e.hash == hash &&\n ((k = e.key) == key || (key != null && key.equals(k))))\n return e;\n } while ((e = e.next) != null);\n }\n }\n return null;\n }<\/code><\/pre>\n\u4e09.TreeMap<\/h3>\n1.\u6982\u8ff0<\/h4>\n\n- TreeMap\u7684\u5e95\u5c42\u901a\u8fc7\u7ea2\u9ed1\u6811\u5b9e\u73b0<\/li>\n
- TreeMap\u7684\u8fed\u4ee3\u5668\u91c7\u7528\u7684\u662f\u4e2d\u5e8f\u904d\u5386\u7684\u65b9\u5f0f<\/li>\n<\/ol>\n
2.\u7ea2\u9ed1\u6811\u7b80\u4ecb<\/h4>\n
\u7ea2\u9ed1\u6811\u53c8\u79f0\u7ea2-\u9ed1\u4e8c\u53c9\u6811<\/strong>\uff0c\u5b83\u9996\u5148\u662f\u4e00\u9897\u4e8c\u53c9\u6811\uff0c\u5b83\u5177\u6709\u4e8c\u53c9\u6811\u7684\u6240\u6709\u7279\u6027\uff0c\u540c\u65f6\u7ea2\u9ed1\u6811\u66f4\u662f\u4e00\u9897\u81ea\u5e73\u8861\u7684\u6392\u5e8f\u4e8c\u53c9\u6811<\/p>\n(1).\u5e73\u8861\u4e8c\u53c9\u6811\u7684\u7279\u6027\uff1a<\/h5>\n
1.\u662f\u4e00\u9897\u7a7a\u6811\u6216\u5b83\u7684\u5de6\u53f3\u4e24\u4e2a\u5b50\u6811\u7684\u9ad8\u5ea6\u5dee\u7edd\u5bf9\u503c\u4e0d\u8d85\u8fc71\u3002
\n2.\u5de6\u53f3\u4e24\u4e2a\u5b50\u6811\u90fd\u662f\u5e73\u8861\u4e8c\u53c9\u6811\u3002<\/p>\n
(2).\u7ea2\u9ed1\u6811\u7684\u89c4\u5219\uff1a<\/h5>\n\n- \u6bcf\u4e2a\u8282\u70b9\u90fd\u53ea\u80fd\u662f\u7ea2\u8272\u6216\u8005\u9ed1\u8272\u3002<\/li>\n
- \u6839\u7ed3\u70b9\u662f\u9ed1\u8272\u3002<\/li>\n
- \u6bcf\u4e2a\u53f6\u7ed3\u70b9(NIL\u7ed3\u70b9\uff0c\u7a7a\u7ed3\u70b9)\u662f\u9ed1\u8272\u7684\u3002<\/li>\n
- \u5982\u679c\u4e00\u4e2a\u7ed3\u70b9\u662f\u7ea2\u8272\u7684\uff0c\u90a3\u4e2a\u5b83\u7684\u4e24\u4e2a\u5b50\u7ed3\u70b9\u90fd\u662f\u9ed1\u8272\u7684\uff0c\u4e00\u6761\u8def\u5f84\u4e0a\u4e0d\u80fd\u51fa\u73b0\u76f8\u90bb\u7684\u4e24\u4e2a\u7ea2\u8272\u7ed3\u70b9\u3002<\/li>\n
- \u4ece\u4efb\u4e00\u7ed3\u70b9\u5230\u5176\u6bcf\u4e2a\u53f6\u5b50\u7684\u6240\u6709\u8def\u5f84\u90fd\u5305\u542b\u76f8\u540c\u6570\u76ee\u7684\u9ed1\u8272\u7ed3\u70b9\u3002<\/li>\n<\/ol>\n
3.\u7279\u70b9<\/h4>\n\n- TreeMap\u5b58\u50a8\u662f\u65e0\u5e8f\u7684<\/li>\n
- TreeMap\u4e0d\u5141\u8bb8\u91cd\u590d\u5b58\u5165\u76f8\u540c\u7684\u5143\u7d20<\/li>\n
- TreeMap\u53ef\u4ee5\u6392\u5e8f<\/li>\n<\/ol>\n
4.\u6392\u5e8f\u89c4\u5219<\/h4>\n\n- TreeMap\u4e2dkey\u53ef\u4ee5\u81ea\u52a8\u5bf9String\u7c7b\u578b\u62168\u5927\u57fa\u672c\u6570\u636e\u7c7b\u578b\u7684\u5305\u88c5\u7c7b\u8fdb\u884c\u6392\u5e8f<\/li>\n
- TreeMap\u65e0\u6cd5\u76f4\u63a5\u5bf9\u81ea\u5b9a\u4e49\u7c7b\u578b\u8fdb\u884c\u6392\u5e8f<\/li>\n<\/ol>\n
5.\u81ea\u5b9a\u4e49\u7c7b\u578b\u5982\u4f55\u6392\u5e8f<\/h4>\n
\u5982\u679c\u76f4\u63a5\u5c06\u81ea\u5b9a\u4e49\u7c7b\u578b\u6dfb\u52a0\u5230TreeMap\u4e2d\uff0ckey\u4f1a\u62a5 java.lang.ClassCastException
\n\u539f\u56e0\uff1a<\/strong>\u81ea\u5b9a\u4e49\u6ca1\u6709\u5b9e\u73b0 java.lang.Comparable \u63a5\u53e3(\u6b64\u65f6\uff0c\u4f7f\u7528\u7684\u662fTreeMap\u7684\u65e0\u53c2\u6784\u9020\u5668)\uff0c\u5982\u679c\u60f3\u8981\u6392\u5e8f\uff0c\u5fc5\u987b\u8981\u6307\u5b9a\u6392\u5e8f\u89c4\u5219\uff0c\u4e3b\u8981\u6709\u4ee5\u4e0b\u4e24\u79cd\u89e3\u51b3\u529e\u6cd5<\/p>\n(1).\u65b9\u6cd5\u4e00<\/h5>\n
\u653e\u5728\u96c6\u5408\u4e2d\u7684\u81ea\u5b9a\u4e49\u7c7b\u578b\u5b9e\u73b0 java.lang.Comparable \u63a5\u53e3\uff0c\u91cd\u5199 compareTo \u65b9\u6cd5\u3002<\/p>\n
public class cat implements Comparable<cat>{\n int age ;\n\n public cat(int age){\n this.age = age;\n }\n\n @Override\n public int compareTo(cat c) {\n \/\/\u6309\u7167\u5e74\u9f84\u5347\u5e8f\u6392\u5e8f\n return this.age-c.age;\n }\n\n}<\/code><\/pre>\n(2).\u65b9\u6cd5\u4e8c<\/h5>\n
\u9009\u62e9\u5e26\u6bd4\u8f83\u5668\u53c2\u6570\u7684\u6784\u9020\u5668\uff0c\u5e76\u91cd\u5199\u6bd4\u8f83\u5668\u4e2d\u7684 compare\u65b9\u6cd5\u3002
\n\u5982\u679c\u91c7\u7528\u8fd9\u79cd\u65b9\u5f0f\uff0c\u5728\u4f20\u9012\u6bd4\u8f83\u5668\u53c2\u6570\u7ed9\u6784\u9020\u5668\u65f6\u6709\u4ee5\u4e0b3\u79cd\u5199\u6cd5<\/p>\n
\n- \n
\u5b9a\u4e49\u4e00\u4e2a Comparator \u63a5\u53e3\u7684\u5b9e\u73b0\u7c7b<\/p>\n
\/\/\u81ea\u5b9a\u4e49Cat\u7c7b\npublic class cat{\nint age ;\n\npublic cat(int age){\n this.age = age;\n}\n}\n\/\/\u63a5\u53e3\u5b9e\u73b0\u7c7b\nclass MyCat implements Comparator<Cat>{\n @Override\n public int compare(Cat o1, Cat o2) {\n return o1.age-o2.age;\n }\n}\n\/\/\u521b\u5efa\u53ef\u6392\u5e8f\u7684TreeMap\npublic static void main(String[] args) {\n TreeMap<Cat, Object> TreeMap = new TreeMap<>(new MyCat());\n}<\/code><\/pre>\n<\/li>\n- \n
\u4f7f\u7528\u533f\u540d\u5185\u90e8\u7c7b<\/p>\n
\/\/\u81ea\u5b9a\u4e49Cat\u7c7b\npublic class cat{\nint age ;\n\npublic cat(int age){\n this.age = age;\n}\n}\n\/\/\u521b\u5efaTreeMap\npublic static void main(String[] args) {\n TreeMap<Cat, Object> TreeMap = new TreeMap<>(new Comparator<Cat>() {\n @Override\n public int compare(Cat o1, Cat o2) {\n return o1.age - o2.age;\n }\n });\n}<\/code><\/pre>\n<\/li>\n- \n
\u4f7f\u7528lambda\u8868\u8fbe\u5f0f(Comparator\u662f\u51fd\u6570\u5f0f\u63a5\u53e3)<\/p>\n
\/\/\u81ea\u5b9a\u4e49Cat\u7c7b\npublic class cat{\nint age ;\n\npublic cat(int age){\n this.age = age;\n}\n}\n\/\/\u521b\u5efaTreeMap\npublic static void main(String[] args) {\n TreeMap<Cat, Object> TreeMap = new TreeMap<>((o1,o2)->o1.age-o2.age);\n}\n\/\/\u6216\u8005\u662f\npublic static void main(String[] args) {\n TreeMap<Cat, Object> TreeMap = new TreeMap<>(Comparator.comparingInt(o -> o.age));\n}<\/code><\/pre>\n<\/li>\n<\/ol>\n(3).\u5982\u4f55\u9009\u62e9\u89e3\u51b3\u65b9\u6848<\/h5>\n\n- \u5f53\u6bd4\u8f83\u89c4\u5219\u4e0d\u4f1a\u53d1\u751f\u6539\u53d8\uff0c\u6216\u8005\u6bd4\u8f83\u89c4\u5219\u53ea\u6709\u4e00\u4e2a\u65f6\uff0c\u5efa\u8bae\u4f7f\u7528\u65b9\u6cd5\u4e00<\/li>\n
- \u5f53\u6bd4\u8f83\u89c4\u5219\u6709\u591a\u4e2a\uff0c\u5e76\u4e14\u9700\u8981\u5728\u591a\u4e2a\u89c4\u5219\u4e2d\u5207\u6362\u65f6\uff0c\u5efa\u8bae\u4f7f\u7528\u65b9\u6cd5\u4e8c<\/li>\n<\/ol>\n
6.\u5185\u90e8\u53c2\u6570<\/h4>\n\/\/\u6392\u5e8f\u7528\u7684\u6bd4\u8f83\u5668\nprivate final Comparator<? super K> comparator;\n\/\/\u5934\u7ed3\u70b9\nprivate transient Entry<K,V> root;\n\/\/\u5927\u5c0f\nprivate transient int size = 0;\n\/\/\u4fee\u6539\u6b21\u6570\nprivate transient int modCount = 0;<\/code><\/pre>\n7.put\u65b9\u6cd5<\/h4>\npublic V put(K key, V value) {\n \/\/\u9996\u5148\u83b7\u53d6\u5230\u5934\u7ed3\u70b9\n Entry<K,V> t = root;\n \/\/\u5982\u679c\u5934\u7ed3\u70b9\u662f\u7a7a\u7684\uff0c\u8c03\u7528\u6bd4\u8f83\u5668\uff0c\u68c0\u67e5key\u662f\u4e0d\u662f\u7a7a\u7684\n if (t == null) {\n compare(key, key); \/\/ type (and possibly null) check\n \/\/\u56e0\u4e3a\u5934\u7ed3\u70b9\u662f\u7a7a\u7684\uff0c\u6240\u4ee5\u628a\u8fd9\u4e2a\u7ed3\u70b9\u4fdd\u5b58\u4e3a\u5934\u7ed3\u70b9\n \/\/\u56e0\u4e3a\u6ca1\u6709\u7236\u7ed3\u70b9\uff0c\u6240\u4ee5\u4f20\u5165\u4e86\u4e00\u4e2anull\n root = new Entry<>(key, value, null);\n \/\/\u957f\u5ea6\u589e\u52a0\u5230\u4e861\n size = 1;\n \/\/\u64cd\u4f5c\u6b21\u6570++\n modCount++;\n return null;\n }\n int cmp;\n Entry<K,V> parent;\n \/\/ split comparator and comparable paths\n \/\/\u83b7\u53d6\u5185\u90e8\u7684\u6bd4\u8f83\u5668\n Comparator<? super K> cpr = comparator;\n \/\/\u5982\u679c\u6bd4\u8f83\u5668\u4e0d\u662f\u7a7a\uff0c\u6309\u7740\u6bd4\u8f83\u5668\u7684\u89c4\u5219\u6267\u884c\n if (cpr != null) {\n do {\n \/\/\u5c06\u6839\u8282\u70b9\u8d4b\u503c\u7ed9parent\n parent = t;\n \/\/\u6bd4\u8f83key\u4e0e\u6839\u8282\u70b9\u7684\u5927\u5c0f\n cmp = cpr.compare(key, t.key);\n if (cmp < 0)\n \/\/\u5982\u679ckey<\u6839\u8282\u70b9\u7684key\uff0c\u6307\u5411\u5de6\u5b50\u6811\n t = t.left;\n else if (cmp > 0)\n \/\/\u5982\u679ckey>\u6839\u8282\u70b9\u7684key\uff0c\u6307\u5411\u53f3\u5b50\u6811\n t = t.right;\n else\n \/\/\u5982\u679c\u76f8\u540c\u8986\u76d6value\n return t.setValue(value);\n } while (t != null);\n }\n \/\/\u6ca1\u6709\u8bbe\u7f6e\u6bd4\u8f83\u5668\uff0c\u91c7\u7528\u81ea\u7136\u6392\u5e8f\u89c4\u5219\n else {\n if (key == null)\n throw new NullPointerException();\n @SuppressWarnings("unchecked")\n \/\/\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\n Comparable<? super K> k = (Comparable<? super K>) key;\n do {\n \/\/\u6b64\u5904\u4e0e\u4e0a\u65b9\u903b\u8f91\u4e00\u81f4\n parent = t;\n cmp = k.compareTo(t.key);\n if (cmp < 0)\n t = t.left;\n else if (cmp > 0)\n t = t.right;\n else\n return t.setValue(value);\n } while (t != null);\n }\n \/\/\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u7ed3\u70b9\uff0c\u5e76\u6307\u5b9a\u7236\u8282\u70b9\n Entry<K,V> e = new Entry<>(key, value, parent);\n \/\/\u6839\u636e\u6bd4\u8f83\u7ed3\u679c\uff0c\u51b3\u5b9a\u65b0\u7ed3\u70b9\u4e3a\u7236\u8282\u70b9\u7684\u5de6\u5b69\u5b50\u8fd8\u662f\u53f3\u5b69\u5b50\n if (cmp < 0)\n parent.left = e;\n else\n parent.right = e;\n \/\/\u65b0\u63d2\u5165\u7ed3\u70b9\u540e\u9700\u8981\u91cd\u65b0\u8c03\u6574\u7ea2\u9ed1\u6811\n fixAfterInsertion(e);\n size++;\n modCount++;\n return null;\n }<\/code><\/pre>\n\u603b\u7ed3\uff1a<\/p>\n
\n- TreeMap\u7684put\u65b9\u6cd5\u4e3b\u8981\u5206\u4e3a\u6784\u5efa\u6392\u5e8f\u4e8c\u53c9\u6811<\/strong>\u548c\u5e73\u8861\u4e8c\u53c9\u6811\u4e24\u4e2a\u6b65\u9aa4<\/strong><\/li>\n
- \u6dfb\u52a0\u7ed3\u70b9\u7684\u8fc7\u7a0b\u5982\u4e0b\n
\n- \u4ee5\u6839\u8282\u70b9\u4e3a\u521d\u59cb\u7ed3\u70b9\u8fdb\u884c\u68c0\u7d22<\/li>\n
- \u901a\u8fc7\u6bd4\u8f83\u5668\uff0c\u4e0e\u5f53\u524d\u7ed3\u70b9\u8fdb\u884c\u6bd4\u8f83\uff0c\u5982\u679c\u65b0\u589e\u7ed3\u70b9\u503c\u6bd4\u8f83\u5927\uff0c\u90a3\u4e48\u5c31\u4ee5\u5f53\u524d\u7ed3\u70b9\u7684\u53f3\u5b50\u7ed3\u70b9\u4f5c\u4e3a\u65b0\u7684\u5f53\u524d\u7ed3\u70b9\uff0c\u5426\u5219\u4ee5\u5de6\u5b50\u7ed3\u70b9\u4f5c\u4e3a\u65b0\u7684\u5f53\u524d\u7ed3\u70b9<\/li>\n
- \u627e\u5230\u5408\u9002\u7684\u53f6\u5b50\u7ed3\u70b9\u540e\uff0c\u5c06\u65b0\u589e\u7ed3\u70b9\u4e0e\u8be5\u7ed3\u70b9\u6bd4\u8f83\uff0c\u5982\u679c\u65b0\u589e\u7ed3\u70b9\u5927\uff0c\u5219\u6dfb\u52a0\u4e3a\u53f3\u5b50\u7ed3\u70b9\uff0c\u5426\u5219\u4e3a\u5de6\u5b50\u7ed3\u70b9<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n
\u56db.LinkedHashMap<\/h3>\n1.\u6982\u8ff0<\/h4>\n
HashMap\u548c\u53cc\u5411\u94fe\u8868\u7ed3\u5408\u5728\u4e00\u8d77\u5c31\u662fLinkedHashMap,\u5b83\u662f\u4e00\u4e2a\u5c06\u6240\u6709\u7ed3\u70b9\u94fe\u5165\u4e00\u4e2a\u53cc\u5411\u94fe\u8868HashMap,\u56e0\u5176\u662fHashMap\u7684\u5b50\u7c7b\uff0c\u6240\u4ee5\u5b83\u81ea\u7136\u62e5\u6709HashMap\u7684\u6240\u6709\u7279\u6027\u3002<\/p>\n
2.\u7279\u70b9<\/h4>\n
LinkedHashMap\u589e\u52a0\u4e86\u65f6\u95f4\u548c\u7a7a\u95f4\u4e0a\u7684\u5f00\u9500\uff0c\u4f46\u662f\u5b83\u901a\u8fc7\u7ef4\u62a4\u4e00\u4e2a\u989d\u5916\u7684\u53cc\u5411\u94fe\u8868\u4fdd\u8bc1\u4e86\u6570\u636e\u7684\u63d2\u5165\u987a\u5e8f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e00.Map 1.\u7279\u70b9 Map \u548c Collection \u6ca1\u6709\u7ee7\u627f\u5173\u7cfb Map \u4ee5(key,value)\u7684\u5f62\u5f0f\u5b58\u50a8\u6570\u636e\uff1a(\u952e\u503c\u5bf9), …<\/p>","protected":false},"author":1,"featured_media":639,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[51,55,54,52,53],"_links":{"self":[{"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/posts\/632"}],"collection":[{"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/comments?post=632"}],"version-history":[{"count":19,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/posts\/632\/revisions"}],"predecessor-version":[{"id":780,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/posts\/632\/revisions\/780"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/media\/639"}],"wp:attachment":[{"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/media?parent=632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/categories?post=632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bigwer.cn\/index.php\/wp-json\/wp\/v2\/tags?post=632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}