{"id":37400,"date":"2023-12-11T14:41:18","date_gmt":"2023-12-11T06:41:18","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=37400"},"modified":"2023-12-11T14:41:18","modified_gmt":"2023-12-11T06:41:18","slug":"%e8%af%b4%e4%b8%80%e8%af%b4-arraylist-%e7%9a%84%e6%89%a9%e5%ae%b9%e6%9c%ba%e5%88%b6%e5%90%a7","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/12\/11\/%e8%af%b4%e4%b8%80%e8%af%b4-arraylist-%e7%9a%84%e6%89%a9%e5%ae%b9%e6%9c%ba%e5%88%b6%e5%90%a7\/","title":{"rendered":"\u8bf4\u4e00\u8bf4 ArrayList \u7684\u6269\u5bb9\u673a\u5236\u5427?"},"content":{"rendered":"

“`”   ArrayList\u662fList\u63a5\u53e3\u7684\u5b9e\u73b0\u7c7b\uff0c\u5b83\u662f\u652f\u6301\u6839\u636e\u9700\u8981\u800c\u52a8\u6001\u589e\u957f\u7684\u6570\u7ec4\u3002java\u4e2d\u6807\u51c6\u6570\u7ec4\u662f\u5b9a\u957f\u7684\uff0c\u5728\u6570\u7ec4\u88ab\u521b\u5efa\u4e4b\u540e\uff0c\u5b83\u4eec\u4e0d\u80fd\u88ab\u52a0\u957f\u6216\u7f29\u77ed\u3002\u8fd9\u5c31\u610f\u5473\u7740\u5728\u521b\u5efa\u6570\u7ec4\u65f6\u9700\u8981\u77e5\u9053\u6570\u7ec4\u7684\u6240\u9700\u957f\u5ea6\uff0c\u4f46\u6709\u65f6\u6211\u4eec\u9700\u8981\u52a8\u6001\u7a0b\u5e8f\u4e2d\u83b7\u53d6\u6570\u7ec4\u957f\u5ea6\u3002ArrayList\u5c31\u662f\u4e3a\u6b64\u800c\u751f\u7684\u3002<\/p>\n

<span style=""font-size: 1rem;"">\u00a0 \u56e0\u6b64\uff0c\u4e86\u89e3\u5b83\u7684\u6269\u5bb9\u673a\u5236\u5bf9\u4f7f\u7528\u5b83\u5c24\u4e3a\u91cd\u8981\u3002<\/span><br><\/p>\n

<span style=""font-size: 1rem;"">\u00a0 ArrayList\u6269\u5bb9\u53d1\u751f\u5728add()\u65b9\u6cd5\u8c03\u7528\u7684\u65f6\u5019\uff0c\u4e0b\u9762\u662fadd()\u65b9\u6cd5\u7684\u6e90\u7801\uff1a<\/span><br><\/p><\/p>\n

<pre><span style=""font-size: 1rem;"">\u00a0 \u00a0 public boolean add(E e) {<br><\/span>\u00a0 \u00a0 \u00a0 \u00a0\/\/\u6269\u5bb9<br>\u00a0 \u00a0 \u00a0 \u00a0 ensureCapacityInternal(size + 1);\u00a0 \/\/ Increments modCount!!<br>\u00a0 \u00a0 \u00a0 \u00a0 elementData[size++] = e;<br>\u00a0 \u00a0 \u00a0 \u00a0 return true;<br>\u00a0 \u00a0 }<\/pre><\/p>\n

\u6839\u636e\u610f\u601d\u53ef\u4ee5\u770b\u51faensureCapacityInternal()\u662f\u7528\u6765\u6269\u5bb9\u7684\uff0c\u5f62\u53c2\u4e3a\u6700\u5c0f\u6269\u5bb9\u91cf\uff0c\u8fdb\u5165\u6b64\u65b9\u6cd5\u540e\uff1a<\/p>\n

<br><\/p>\n

<pre>private void ensureCapacityInternal(int minCapacity) {<br>\u00a0 \u00a0 ensureExplicitCapacity(calculateCapacity(elementData, minCapacity));<br>}<\/pre><\/p>\n

<br><\/p>\n

\u00a0 \u00a0\u901a\u8fc7\u65b9\u6cd5calculateCapacity(elementData, minCapacity)\u83b7\u53d6:<\/p>\n

<pre><span style=""font-size: 1rem;"">\u00a0 \u00a0 private static int calculateCapacity(Object[] elementData, int minCapacity) {<br><\/span>\u00a0 \u00a0 \u00a0 \u00a0 \/\/\u5982\u679c\u4f20\u5165\u7684\u662f\u4e2a\u7a7a\u6570\u7ec4\u5219\u6700\u5c0f\u5bb9\u91cf\u53d6\u9ed8\u8ba4\u5bb9\u91cf\u4e0eminCapacity\u4e4b\u95f4\u7684\u6700\u5927\u503c<br>\u00a0 \u00a0 \u00a0 \u00a0 if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 return Math.max(DEFAULT_CAPACITY, minCapacity);<br>\u00a0 \u00a0 \u00a0 \u00a0 }<br>\u00a0 \u00a0 \u00a0 \u00a0 return minCapacity;<br>\u00a0 \u00a0 }<\/pre><\/p>\n

<br><\/p>\n

ensureExplicitCapacity\u65b9\u6cd5\u53ef\u4ee5\u5224\u65ad\u662f\u5426\u9700\u8981\u6269\u5bb9\uff1a<\/p>\n

<br><\/p>\n

<pre>\u00a0private void ensureExplicitCapacity(int minCapacity) {<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 modCount++;<br>\u00a0<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ \u5982\u679c\u6700\u5c0f\u9700\u8981\u7a7a\u95f4\u6bd4elementData\u7684\u5185\u5b58\u7a7a\u95f4\u8981\u5927\uff0c\u5219\u9700\u8981\u6269\u5bb9<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 if (minCapacity – elementData.length > 0)<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/\u6269\u5bb9<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 grow(minCapacity);<br>\u00a0 \u00a0 \u00a0 }<\/pre><\/p>\n

<br><\/p>\n

\u00a0 \u00a0\u63a5\u4e0b\u6765\u91cd\u70b9\u6765\u4e86\uff0cArrayList\u6269\u5bb9\u7684\u5173\u952e\u65b9\u6cd5grow():<\/p>\n

<pre><span style=""font-size: 1rem;"">\u00a0 private void grow(int minCapacity) {<br><\/span>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ \u83b7\u53d6\u5230ArrayList\u4e2delementData\u6570\u7ec4\u7684\u5185\u5b58\u7a7a\u95f4\u957f\u5ea6<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 int oldCapacity = elementData.length;<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ \u6269\u5bb9\u81f3\u539f\u6765\u76841.5\u500d<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0int newCapacity = oldCapacity + (oldCapacity >> 1);<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ \u518d\u5224\u65ad\u4e00\u4e0b\u65b0\u6570\u7ec4\u7684\u5bb9\u91cf\u591f\u4e0d\u591f\uff0c\u591f\u4e86\u5c31\u76f4\u63a5\u4f7f\u7528\u8fd9\u4e2a\u957f\u5ea6\u521b\u5efa\u65b0\u6570\u7ec4\uff0c<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ \u4e0d\u591f\u5c31\u5c06\u6570\u7ec4\u957f\u5ea6\u8bbe\u7f6e\u4e3a\u9700\u8981\u7684\u957f\u5ea6<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0if (newCapacity – minCapacity < 0)<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0newCapacity = minCapacity;<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/\u82e5\u9884\u8bbe\u503c\u5927\u4e8e\u9ed8\u8ba4\u7684\u6700\u5927\u503c\u68c0\u67e5\u662f\u5426\u6ea2\u51fa<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0if (newCapacity – MAX_ARRAY_SIZE > 0)<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0newCapacity = hugeCapacity(minCapacity);<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ \u8c03\u7528Arrays.copyOf\u65b9\u6cd5\u5c06elementData\u6570\u7ec4\u6307\u5411\u65b0\u7684\u5185\u5b58\u7a7a\u95f4\u65f6newCapacity\u7684\u8fde\u7eed\u7a7a\u95f4<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ \u5e76\u5c06elementData\u7684\u6570\u636e\u590d\u5236\u5230\u65b0\u7684\u5185\u5b58\u7a7a\u95f4<br>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0elementData = Arrays.copyOf(elementData, newCapacity);<br>\u00a0 \u00a0 \u00a0}<\/pre><\/p>\n

<span style=""font-size: 1rem;"">\u00a0\u4ece\u6b64\u65b9\u6cd5\u4e2d\u6211\u4eec\u53ef\u4ee5\u6e05\u6670\u7684\u770b\u51fa\u5176\u5b9e<b>ArrayList\u6269\u5bb9\u7684\u672c\u8d28\u5c31\u662f\u8ba1\u7b97\u51fa\u65b0\u7684\u6269\u5bb9\u6570\u7ec4\u7684size\u540e\u5b9e\u4f8b\u5316\uff0c\u5e76\u5c06\u539f\u6709\u6570\u7ec4\u5185\u5bb9\u590d\u5236\u5230\u65b0\u6570\u7ec4\u4e2d\u53bb<\/b>\u3002<\/span><\/p>\n

\u5230\u6b64\u6269\u5bb9\u5c31\u57fa\u672c\u5b8c\u6210\u4e86\u3002<\/p>\n

<pre><code> "“`
\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"

“`”   ArrayList\u662fList\u63a5\u53e3\u7684\u5b9e\u73b0\u7c7b\uff0c\u5b83\u662f\u652f\u6301\u6839\u636e\u9700\u8981\u800c\u52a8\u6001 […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-37400","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/37400","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=37400"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/37400\/revisions"}],"predecessor-version":[{"id":37401,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/37400\/revisions\/37401"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=37400"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=37400"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=37400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}