javaarraylisttime-complexity 76 ArrayList在 Java 中是一个列表(list),但底层实现是数组(array)。对于 get 操作的时间复杂度是O(1)。 -Hidayat 6个回答 126 在Java中,ArrayList是由array支持的List。get(index)方法是一个常数时间复杂度为O(1)的操作。ArrayList.get(index)的代码直接来自于Java库: ...
增删改查,对应到 ArrayList 和 LinkedList,就是 add(E e)、remove(int index)、add(int index, E element)、get(int index),我来给大家一一分析下,它们对应的时间复杂度,也就明白了“ArrayList 底层是数组,查询快、增删慢;LinkedList 底层是链表,查询慢、增删快”这个结论很荒唐的原因 对于ArrayList 来说: 1...
ArrayList是一个可变大小的数组,常用于存储数据。 importjava.util.ArrayList;publicclassTimeComplexityDemo{publicstaticvoidmain(String[]args){// 创建一个新的 ArrayList,用于存储 String 类型的数据ArrayList<String>arrayList=newArrayList<>();// 测试插入时间复杂度arrayList.add("Java");arrayList.add("Python")...
这也是 ArrayList 的最大优点。 2)add(E e)方法会默认将元素添加到数组末尾,但需要考虑到数组扩容的情况,如果不需要扩容,时间复杂度为O(1)。 publicbooleanadd(E e){ modCount++; add(e, elementData, size);returntrue; }privatevoidadd(E e, Object[] elementData,ints){if(s == elementData.length) ...
Add a comment 1 its O(n). contains(Object o) is implemented on indexOf() which takes O(n). So complexity of contains(Object o) is defensively O(n) Here are some other if you need: add() - O(1) add(index, element) – O(n) get() – O(1) set() – O(1) remove()...
public boolean add(E e) { ensureCapacityInternal(size + 1); elementData[size++] = e; return true; } 执行elementData[size++] = e。 此时: size 为 0 e为 “沉默王二” 所以数组的第一个元素(下标为 0) 被赋值为“沉默王二”,接着返回 true,第一次 add 方法执行完毕。 PS:add 过程中会遇到一...
However, in the worst case, if the resizing happens, the time complexity is O(n), where n is the current size of the ArrayList. add(index, e) and remove(e): have a time complexity of O(n), as it may need to shift existing elements. get(i) and set(i, e): have a constant ...
performanceloopsarraylisttime-complexityjava-8 作者 2019 08-06 -6 推荐指数 1 解决办法 100 查看次数 ArrayList<String[]> 中的字符串 如何检查内部是否存在特定的字符串ArrayList<String[]>? 我是否需要迭代每个项目并检查字符串或为此目的的任何特定方法(如ArrayList.contains())?
The size, isEmpty, get, set, iterator, and listIterator operations run in constant time. The add operation runs in amortized constant time, that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking). The constant factor is low compare...
However, in the worst case, if the resizing happens, the time complexity is O(n), where n is the current size of the ArrayList. add(index, e) and remove(e): have a time complexity of O(n), as it may need to shift existing elements. get(i) and set(i, e): have a constant ...