{"id":1499,"date":"2019-06-19T14:41:01","date_gmt":"2019-06-19T06:41:01","guid":{"rendered":"http:\/\/www.yusian.com\/blog\/?p=1499"},"modified":"2020-12-01T21:26:21","modified_gmt":"2020-12-01T13:26:21","slug":"%e9%9a%8f%e6%9c%ba%e5%ad%98%e5%82%a8%e5%ae%9e%e7%8e%b0%e5%8a%a8%e6%80%81%e6%95%b0%e7%bb%84arraylist","status":"publish","type":"post","link":"https:\/\/www.yusian.com\/blog\/java\/2019\/06\/19\/1441011499.html","title":{"rendered":"\u968f\u673a\u5b58\u50a8\u5b9e\u73b0\u52a8\u6001\u6570\u7ec4ArrayList"},"content":{"rendered":"<p>1\u3001List<\/p>\n\n\n<pre lang=\"java\" line=\"1\">\npackage com.yusian;\n\npublic interface List<E> {\n\t\n\tstatic final int ELEMENT_NOT_FOUND = -1;\n\t\/**\n\t * \u83b7\u53d6\u6570\u7ec4\u957f\u5ea6\n\t * @return \u6570\u7ec4\u957f\u5ea6\n\t *\/\n\tpublic int size();\n\t\n\t\/**\n\t * \u662f\u5426\u4e3a\u7a7a\n\t * @return true \/ false\n\t *\/\n\tpublic boolean isEmpty();\n\t\n\t\/**\n\t * \u662f\u5426\u5305\u542b\u67d0\u5143\u7d20\n\t * @param element\n\t * @return true \/ false\n\t *\/\n\tpublic boolean contains(E element);\n\t\n\t\/**\n\t * \u6dfb\u52a0\u5143\u7d20\uff0c\u9ed8\u8ba4\u6dfb\u52a0\u5230\u672b\u5c3e\u4f4d\u7f6e\n\t * @param element\n\t *\/\n\tpublic void add(E element);\n\t\n\t\/**\n\t * \u83b7\u53d6\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @return \u503c\n\t *\/\n\tpublic E get(int index);\n\t\n\t\/**\n\t * \u66ff\u6362\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @param element \u5143\u7d20\n\t * @return \u539f\u5143\u7d20\u5185\u5bb9\n\t *\/\n\tpublic E set(int index, E element);\n\t\n\t\/**\n\t * \u6dfb\u52a0\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @param element \u5143\u7d20\u503c\n\t *\/\n\tpublic void add(int index, E element);\n\t\n\t\/**\n\t * \u79fb\u9664\u5143\u7d20\n\t * @return \u8fd4\u56de\u88ab\u79fb\u9664\u5143\u7d20\n\t *\/\n\tpublic E remove(int index);\n\t\n\t\/**\n\t * \u83b7\u53d6\u5143\u7d20\u7d22\u5f15\n\t * @param element\n\t * @return \u7d22\u5f15\n\t *\/\n\tpublic int indexOf(E element);\n\t\n\t\/**\n\t * \u6e05\u9664\u6570\u7ec4\n\t *\/\n\tpublic void clear();\n}\n\n<\/pre>\n\n\n<p>2\u3001AbstractList<\/p>\n\n\n<!--more-->\n\n\n\n<pre lang=\"java\" line=\"1\">\npackage com.yusian;\n\npublic abstract class AbstractList<E> implements List<E> {\n\n\tprotected int size;\n\t\n\t\/**\n\t * \u83b7\u53d6\u6570\u7ec4\u957f\u5ea6\n\t * @return \u6570\u7ec4\u957f\u5ea6\n\t *\/\n\tpublic int size() {\n\t\treturn size;\n\t}\n\t\n\t\/**\n\t * \u662f\u5426\u4e3a\u7a7a\n\t * @return true \/ false\n\t *\/\n\tpublic boolean isEmpty() {\n\t\treturn size == 0;\n\t}\n\t\n\t\/**\n\t * \u662f\u5426\u5305\u542b\u67d0\u5143\u7d20\n\t * @param element\n\t * @return true \/ false\n\t *\/\n\tpublic boolean contains(E element) {\n\t\treturn indexOf(element) != ELEMENT_NOT_FOUND;\n\t}\n\t\n\t\/**\n\t * \u6dfb\u52a0\u5143\u7d20\uff0c\u9ed8\u8ba4\u6dfb\u52a0\u5230\u672b\u5c3e\u4f4d\u7f6e\n\t * @param element\n\t *\/\n\tpublic void add(E element) {\n\t\tadd(size, element);\n\t}\n\t\n\t\/**\n\t * \u5185\u90e8\u5224\u65ad\n\t * @param index\n\t *\/\n\tprotected void rangeCheck(int index) {\n\t\tif (index < 0 || index >= size) {\n\t\t\toutOfRange(index);\n\t\t}\n\t}\n\tprotected void rangeCheckForAdd(int index) {\n\t\tif (index < 0 || index > size) {\n\t\t\toutOfRange(index);\n\t\t}\n\t}\n\tprotected void outOfRange(int index) {\n\t\tthrow new IndexOutOfBoundsException(\"\u8d85\u51fa\u8303\u56f4\uff0cIndex:\"+index+\", size:\"+size);\n\t}\n}\n<\/pre>\n\n\n<p>3\u3001ArrayList<\/p>\n\n\n<pre lang=\"java\" line=\"1\">\npackage com.yusian;\n\n@SuppressWarnings(\"unchecked\")\npublic class ArrayList<E> extends AbstractList<E>{\n\n\tprivate E[] elements;\n\tprivate static final int DEFAULT_CAPACITY = 10;\n\n\t\n\tpublic ArrayList() {\n\t\tthis(DEFAULT_CAPACITY);\n\t}\n\t\n\tpublic ArrayList(int capacity) {\n\t\tif (capacity < DEFAULT_CAPACITY) {\n\t\t\tcapacity = DEFAULT_CAPACITY;\n\t\t}\n\t\telements = (E[])new Object[capacity];\n\t}\n\t\/**\n\t * \u83b7\u53d6\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @return \u503c\n\t *\/\n\tpublic E get(int index) {\n\t\trangeCheck(index);\n\t\treturn elements[index];\n\t}\n\t\n\t\/**\n\t * \u66ff\u6362\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @param element \u5143\u7d20\n\t * @return \u539f\u5143\u7d20\u5185\u5bb9\n\t *\/\n\tpublic E set(int index, E element) {\n\t\trangeCheck(index);\n\t\tE old = elements[index];\n\t\telements[index] = element;\n\t\treturn old;\n\t}\n\t\n\t\/**\n\t * \u6dfb\u52a0\u5143\u7d20\n\t * @param index \u7d22\u5f15\n\t * @param element \u5143\u7d20\u503c\n\t *\/\n\tpublic void add(int index, E element) {\n\t\trangeCheckForAdd(index);\n\t\tensureCapcity(size + 1);\n\t\tfor (int i = size; i >= index; i--) {\n\t\t\t\/\/ \u6b64\u5904\u6709\u53ef\u80fd\u8d85\u51faelements\u7684\u6709\u6548\u8303\u56f4\n\t\t\telements[i+1] = elements[i];\n\t\t}\n\t\telements[index] = element;\n\t\tsize++;\n\t}\n\t\n\t\/**\n\t * \u79fb\u9664\u5143\u7d20\n\t * @return \u8fd4\u56de\u88ab\u79fb\u9664\u5143\u7d20\n\t *\/\n\tpublic E remove(int index) {\n\t\trangeCheck(index);\n\t\t\/\/ 0 1 2 3 4 5 6 7\n\t\t\/\/ 1 2 3 4 5 6 7 8\n\t\tE del = elements[index];\n\t\tfor (int i = index; i < size - 1; i++) {\n\t\t\telements[i] = elements[i+1];\n\t\t}\n\t\telements[--size] = null;\n\t\treturn del;\n\t}\n\t\n\t\/**\n\t * \u83b7\u53d6\u5143\u7d20\u7d22\u5f15\n\t * @param element\n\t * @return \u7d22\u5f15\n\t *\/\n\tpublic int indexOf(E element) {\n\t\tif (element == null) {\n\t\t\tfor (int i = 0; i < size; i++) {\n\t\t\t\tif (elements[i] == null) return i;\n\t\t\t}\n\t\t} else {\n\t\t\tfor (int i = 0; i < size; i++) {\n\t\t\t\tif (element.equals(elements[i])) return i;\n\t\t\t\t\/\/ if (element == elements[i]) return i;\n\t\t\t}\n\t\t}\n\t\treturn ELEMENT_NOT_FOUND;\n\t}\n\t\n\t\/**\n\t * \u6e05\u9664\u6570\u7ec4\n\t *\/\n\tpublic void clear() {\n\t\tfor (int i = 0; i < size; i++) {\n\t\t\telements[i] = null;\n\t\t}\n\t\tsize = 0;\n\t}\n\t\n\t@Override\n\tpublic String toString() {\n\t\t\/\/ TODO Auto-generated method stub\n\t\tStringBuilder str = new StringBuilder();\n\t\tstr.append(super.toString()).append(\" size = \").append(size).append(\", [\");\n\t\tfor (int i = 0; i < size; i++) {\n\t\t\tif (i > 0) {\n\t\t\t\tstr.append(\", \");\n\t\t\t}\n\t\t\tstr.append(elements[i]);\n\t\t}\n\t\tstr.append(\"]\");\n\t\treturn str.toString();\n\t}\n\t\n\t\/**\n\t * \u79c1\u6709\u65b9\u6cd5\n\t *\/\n\tprivate void ensureCapcity(int capcity) {\n\t\tif (elements.length > capcity) return;\n\t\tint oldCapcity = elements.length;\n\t\t\/\/ \u6269\u5bb9\u539f\u6765\u7684\u7ea61.5\u500d\n\t\tint newCapcity = oldCapcity + (oldCapcity >> 1);\n\t\tE[] newElements = (E[]) new Object[newCapcity];  \n\t\tfor (int i = 0; i < size; i++) {\n\t\t\tnewElements[i] = elements[i];\n\t\t}\n\t\telements = newElements;\n\t\tSystem.out.println(\"\u5bb9\u91cf\uff1a\" + oldCapcity + \" --> \" + newCapcity);\n\t}\n}\n\n<\/pre>\n\n\n<p>Main<\/p>\n\n\n<pre lang=\"java\" line=\"1\">\npackage com.yusian;\n\npublic class Main {\n\n\tpublic static void main(String[] args) {\n\t\t\/\/ TODO Auto-generated method stub\n\t\tArrayList<Integer> list = new ArrayList<Integer>();\n\t\tlist.add(1);\n\t\tlist.add(2);\n\t\tlist.add(3);\n\t\tlist.add(4);\n\t\tlist.add(5);\n\t\tlist.add(1, 0);\n\t\tSystem.out.println(list);\n\t}\n\n}\n\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>1\u3001List 2\u3001AbstractList<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35,216],"tags":[34,215,212,214,213],"class_list":["post-1499","post","type-post","status-publish","format-standard","hentry","category-java","category-structure","tag-java","tag-215","tag-212","tag-214","tag-213"],"_links":{"self":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts\/1499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/comments?post=1499"}],"version-history":[{"count":0,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts\/1499\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/media?parent=1499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/categories?post=1499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/tags?post=1499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}