Java LinkedList

LinkedList是基于双向链表实现的，先看构造方法和方法

• Constructor Summary

  Constructors

  Constructor	Description
  LinkedList()	Constructs an empty list.
  LinkedList?(Collection<? extends E> c)	Constructs a list containing the elements of the specified collection, in the order they are returned by the collection‘s iterator.

• Method Summary

  All MethodsInstance MethodsConcrete Methods

  Modifier and Type	Method	Description
  void	add?(int index,E element)	Inserts the specified element at the specified position in this list.
  boolean	add?(E e)	Appends the specified element to the end of this list.
  boolean	addAll?(int index,Collection<? extendsE> c)	Inserts all of the elements in the specified collection into this list, starting at the specified position.
  boolean	addAll?(Collection<? extends E> c)	Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection‘s iterator.
  void	addFirst?(E e)	Inserts the specified element at the beginning of this list.
  void	addLast?(E e)	Appends the specified element to the end of this list.
  void	clear()	Removes all of the elements from this list.
  Object	clone()	Returns a shallow copy of this LinkedList.
  boolean	contains?(Object o)	Returns true if this list contains the specified element.
  Iterator<E>	descendingIterator()	Returns an iterator over the elements in this deque in reverse sequential order.
  E	element()	Retrieves, but does not remove, the head (first element) of this list.
  E	get?(int index)	Returns the element at the specified position in this list.
  E	getFirst()	Returns the first element in this list.
  E	getLast()	Returns the last element in this list.
  int	indexOf?(Object o)	Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
  int	lastIndexOf?(Object o)	Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
  ListIterator<E>	listIterator?(int index)	Returns a list-iterator of the elements in this list (in proper sequence), starting at the specified position in the list.
  boolean	offer?(E e)	Adds the specified element as the tail (last element) of this list.
  boolean	offerFirst?(E e)	Inserts the specified element at the front of this list.
  boolean	offerLast?(E e)	Inserts the specified element at the end of this list.
  E	peek()	Retrieves, but does not remove, the head (first element) of this list.
  E	peekFirst()	Retrieves, but does not remove, the first element of this list, or returns null if this list is empty.
  E	peekLast()	Retrieves, but does not remove, the last element of this list, or returns null if this list is empty.
  E	poll()	Retrieves and removes the head (first element) of this list.
  E	pollFirst()	Retrieves and removes the first element of this list, or returns null if this list is empty.
  E	pollLast()	Retrieves and removes the last element of this list, or returns null if this list is empty.
  E	pop()	Pops an element from the stack represented by this list.
  void	push?(E e)	Pushes an element onto the stack represented by this list.
  E	remove()	Retrieves and removes the head (first element) of this list.
  E	remove?(int index)	Removes the element at the specified position in this list.
  boolean	remove?(Object o)	Removes the first occurrence of the specified element from this list, if it is present.
  E	removeFirst()	Removes and returns the first element from this list.
  boolean	removeFirstOccurrence?(Object o)	Removes the first occurrence of the specified element in this list (when traversing the list from head to tail).
  E	removeLast()	Removes and returns the last element from this list.
  boolean	removeLastOccurrence?(Object o)	Removes the last occurrence of the specified element in this list (when traversing the list from head to tail).
  E	set?(int index,E element)	Replaces the element at the specified position in this list with the specified element.
  int	size()	Returns the number of elements in this list.
  Spliterator<E>	spliterator()	Creates a late-binding and fail-fast Spliterator over the elements in this list.
  Object[]	toArray()	Returns an array containing all of the elements in this list in proper sequence (from first to last element).
  <T> T[]	toArray?(T[] a)	Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array

构造方法LinkedList()//创建一个空LinkedList

LinkedList(Coolection<? extends E>)//创建一个有内容的LinkedList，可以将别的LinkedList复制进来（不是引用）

LinkedList增加和删除元素都是常数时间（假设位置已知）

add(int index,E element)向索引位置插入，线性时间

add(E e)默认队尾

addFirst(E e)插入队头

addList(E e)插入队尾

removeFirst(E e)删除队头元素

removeLast(E e)删除队尾元素

LinkedList查询修改元素是线性时间,这点不如ArrayList但是LinkedList的增加和删除是常数时间，不需要移动其他元素的位置。

Java LinkedList

原文：https://www.cnblogs.com/shineyoung/p/10476023.html