程序包 java.util

类 LinkedList<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.AbstractSequentialList<E>

java.util.LinkedList<E>

类型参数:

E - the type of elements held in this collection

所有已实现的接口:

Serializable, Cloneable, Iterable<E>, Collection<E>, Deque<E>, List<E>, Queue<E>

public class LinkedList<E>
extends AbstractSequentialList<E>
implements List<E>, Deque<E>, Cloneable, Serializable

Doubly-linked list implementation of the List and Deque interfaces. Implements all optional list operations, and permits all elements (including null).

All of the operations perform as could be expected for a doubly-linked list. Operations that index into the list will traverse the list from the beginning or the end, whichever is closer to the specified index.

Note that this implementation is not synchronized. If multiple threads access a linked list concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no such object exists, the list should be "wrapped" using the Collections#synchronizedList method. This is best done at creation time, to prevent accidental unsynchronized access to the list:

   List list = Collections.synchronizedList(new LinkedList(...));

The iterators returned by this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the Iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.

This class is a member of the Java Collections Framework.

从以下版本开始:

1.2

另请参阅:

List, ArrayList, 序列化表格

字段概要

从类继承的字段 java.util.AbstractList

modCount

构造器概要

构造器

构造器	说明
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.

方法概要

限定符和类型	方法	说明
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<? extends E> 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.

从类继承的方法 java.util.AbstractCollection

containsAll, isEmpty, removeAll, retainAll, toString

从类继承的方法 java.util.AbstractList

equals, hashCode, listIterator, removeRange, subList

从类继承的方法 java.util.AbstractSequentialList

iterator

从接口继承的方法 java.util.Collection

parallelStream, removeIf, stream

从接口继承的方法 java.util.Deque

iterator

从接口继承的方法 java.lang.Iterable

forEach

从接口继承的方法 java.util.List

containsAll, equals, hashCode, isEmpty, iterator, listIterator, removeAll, replaceAll, retainAll, sort, subList

从类继承的方法 java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

构造器详细资料

LinkedList

public LinkedList()

Constructs an empty list.

LinkedList

public 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.

参数:

c - the collection whose elements are to be placed into this list

抛出:

NullPointerException - if the specified collection is null

方法详细资料

getFirst

public E getFirst()

Returns the first element in this list.

指定者:

getFirst 在接口中 Deque<E>

返回:

the first element in this list

抛出:

NoSuchElementException - if this list is empty

getLast

public E getLast()

Returns the last element in this list.

指定者:

getLast 在接口中 Deque<E>

返回:

the last element in this list

抛出:

NoSuchElementException - if this list is empty

removeFirst

public E removeFirst()

Removes and returns the first element from this list.

指定者:

removeFirst 在接口中 Deque<E>

返回:

the first element from this list

抛出:

NoSuchElementException - if this list is empty

removeLast

public E removeLast()

Removes and returns the last element from this list.

指定者:

removeLast 在接口中 Deque<E>

返回:

the last element from this list

抛出:

NoSuchElementException - if this list is empty

addFirst

public void addFirst(E e)

Inserts the specified element at the beginning of this list.

指定者:

addFirst 在接口中 Deque<E>

参数:

e - the element to add

addLast

public void addLast(E e)

Appends the specified element to the end of this list.

This method is equivalent to add(E).

指定者:

addLast 在接口中 Deque<E>

参数:

e - the element to add

contains

public boolean contains(Object o)

Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that (o==null ? e==null : o.equals(e)).

指定者:

contains 在接口中 Collection<E>

指定者:

contains 在接口中 Deque<E>

指定者:

contains 在接口中 List<E>

覆盖:

contains 在类中 AbstractCollection<E>

参数:

o - element whose presence in this list is to be tested

返回:

true if this list contains the specified element

size

public int size()

Returns the number of elements in this list.

指定者:

size 在接口中 Collection<E>

指定者:

size 在接口中 Deque<E>

指定者:

size 在接口中 List<E>

指定者:

size 在类中 AbstractCollection<E>

返回:

the number of elements in this list

add

public boolean add(E e)

Appends the specified element to the end of this list.

This method is equivalent to addLast(E).

指定者:

add 在接口中 Collection<E>

指定者:

add 在接口中 Deque<E>

指定者:

add 在接口中 List<E>

指定者:

add 在接口中 Queue<E>

覆盖:

add 在类中 AbstractList<E>

参数:

e - element to be appended to this list

返回:

true (as specified by Collection#add)

remove

public boolean remove(Object o)

Removes the first occurrence of the specified element from this list, if it is present. If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists). Returns true if this list contained the specified element (or equivalently, if this list changed as a result of the call).

指定者:

remove 在接口中 Collection<E>

指定者:

remove 在接口中 Deque<E>

指定者:

remove 在接口中 List<E>

覆盖:

remove 在类中 AbstractCollection<E>

参数:

o - element to be removed from this list, if present

返回:

true if this list contained the specified element

addAll

public 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. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)

指定者:

addAll 在接口中 Collection<E>

指定者:

addAll 在接口中 List<E>

覆盖:

addAll 在类中 AbstractCollection<E>

参数:

c - collection containing elements to be added to this list

返回:

true if this list changed as a result of the call

抛出:

NullPointerException - if the specified collection is null

另请参阅:

AbstractCollection.add(Object)

addAll

public boolean addAll(int index,
                      Collection<? extends E> c)

Inserts all of the elements in the specified collection into this list, starting at the specified position. Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified collection's iterator.

指定者:

addAll 在接口中 List<E>

覆盖:

addAll 在类中 AbstractSequentialList<E>

参数:

index - index at which to insert the first element from the specified collection

c - collection containing elements to be added to this list

返回:

true if this list changed as a result of the call

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

NullPointerException - if the specified collection is null

clear

public void clear()

Removes all of the elements from this list. The list will be empty after this call returns.

指定者:

clear 在接口中 Collection<E>

指定者:

clear 在接口中 List<E>

覆盖:

clear 在类中 AbstractList<E>

get

public E get(int index)

Returns the element at the specified position in this list.

指定者:

get 在接口中 List<E>

覆盖:

get 在类中 AbstractSequentialList<E>

参数:

index - index of the element to return

返回:

the element at the specified position in this list

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

set

public E set(int index,
             E element)

Replaces the element at the specified position in this list with the specified element.

指定者:

set 在接口中 List<E>

覆盖:

set 在类中 AbstractSequentialList<E>

参数:

index - index of the element to replace

element - element to be stored at the specified position

返回:

the element previously at the specified position

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

add

public void add(int index,
                E element)

Inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).

指定者:

add 在接口中 List<E>

覆盖:

add 在类中 AbstractSequentialList<E>

参数:

index - index at which the specified element is to be inserted

element - element to be inserted

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

remove

public E remove(int index)

Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.

指定者:

remove 在接口中 List<E>

覆盖:

remove 在类中 AbstractSequentialList<E>

参数:

index - the index of the element to be removed

返回:

the element previously at the specified position

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

indexOf

public 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. More formally, returns the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.

指定者:

indexOf 在接口中 List<E>

覆盖:

indexOf 在类中 AbstractList<E>

参数:

o - element to search for

返回:

the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element

lastIndexOf

public 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. More formally, returns the highest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.

指定者:

lastIndexOf 在接口中 List<E>

覆盖:

lastIndexOf 在类中 AbstractList<E>

参数:

o - element to search for

返回:

the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element

peek

public E peek()

Retrieves, but does not remove, the head (first element) of this list.

指定者:

peek 在接口中 Deque<E>

指定者:

peek 在接口中 Queue<E>

返回:

the head of this list, or null if this list is empty

从以下版本开始:

1.5

element

public E element()

Retrieves, but does not remove, the head (first element) of this list.

指定者:

element 在接口中 Deque<E>

指定者:

element 在接口中 Queue<E>

返回:

the head of this list

抛出:

NoSuchElementException - if this list is empty

从以下版本开始:

1.5

poll

public E poll()

Retrieves and removes the head (first element) of this list.

指定者:

poll 在接口中 Deque<E>

指定者:

poll 在接口中 Queue<E>

返回:

the head of this list, or null if this list is empty

从以下版本开始:

1.5

remove

public E remove()

Retrieves and removes the head (first element) of this list.

指定者:

remove 在接口中 Deque<E>

指定者:

remove 在接口中 Queue<E>

返回:

the head of this list

抛出:

NoSuchElementException - if this list is empty

从以下版本开始:

1.5

offer

public boolean offer(E e)

Adds the specified element as the tail (last element) of this list.

指定者:

offer 在接口中 Deque<E>

指定者:

offer 在接口中 Queue<E>

参数:

e - the element to add

返回:

true (as specified by Queue#offer)

从以下版本开始:

1.5

offerFirst

public boolean offerFirst(E e)

Inserts the specified element at the front of this list.

指定者:

offerFirst 在接口中 Deque<E>

参数:

e - the element to insert

返回:

true (as specified by Deque#offerFirst)

从以下版本开始:

1.6

offerLast

public boolean offerLast(E e)

Inserts the specified element at the end of this list.

指定者:

offerLast 在接口中 Deque<E>

参数:

e - the element to insert

返回:

true (as specified by Deque#offerLast)

从以下版本开始:

1.6

peekFirst

public E peekFirst()

Retrieves, but does not remove, the first element of this list, or returns null if this list is empty.

指定者:

peekFirst 在接口中 Deque<E>

返回:

the first element of this list, or null if this list is empty

从以下版本开始:

1.6

peekLast

public E peekLast()

Retrieves, but does not remove, the last element of this list, or returns null if this list is empty.

指定者:

peekLast 在接口中 Deque<E>

返回:

the last element of this list, or null if this list is empty

从以下版本开始:

1.6

pollFirst

public E pollFirst()

Retrieves and removes the first element of this list, or returns null if this list is empty.

指定者:

pollFirst 在接口中 Deque<E>

返回:

the first element of this list, or null if this list is empty

从以下版本开始:

1.6

pollLast

public E pollLast()

Retrieves and removes the last element of this list, or returns null if this list is empty.

指定者:

pollLast 在接口中 Deque<E>

返回:

the last element of this list, or null if this list is empty

从以下版本开始:

1.6

push

public void push(E e)

Pushes an element onto the stack represented by this list. In other words, inserts the element at the front of this list.

This method is equivalent to addFirst(E).

指定者:

push 在接口中 Deque<E>

参数:

e - the element to push

从以下版本开始:

1.6

pop

public E pop()

Pops an element from the stack represented by this list. In other words, removes and returns the first element of this list.

This method is equivalent to removeFirst().

指定者:

pop 在接口中 Deque<E>

返回:

the element at the front of this list (which is the top of the stack represented by this list)

抛出:

NoSuchElementException - if this list is empty

从以下版本开始:

1.6

removeFirstOccurrence

public boolean removeFirstOccurrence(Object o)

Removes the first occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not contain the element, it is unchanged.

指定者:

removeFirstOccurrence 在接口中 Deque<E>

参数:

o - element to be removed from this list, if present

返回:

true if the list contained the specified element

从以下版本开始:

1.6

removeLastOccurrence

public boolean removeLastOccurrence(Object o)

Removes the last occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not contain the element, it is unchanged.

指定者:

removeLastOccurrence 在接口中 Deque<E>

参数:

o - element to be removed from this list, if present

返回:

true if the list contained the specified element

从以下版本开始:

1.6

listIterator

public 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. Obeys the general contract of List.listIterator(int).

The list-iterator is fail-fast: if the list is structurally modified at any time after the Iterator is created, in any way except through the list-iterator's own remove or add methods, the list-iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

指定者:

listIterator 在接口中 List<E>

指定者:

listIterator 在类中 AbstractSequentialList<E>

参数:

index - index of the first element to be returned from the list-iterator (by a call to next)

返回:

a ListIterator of the elements in this list (in proper sequence), starting at the specified position in the list

抛出:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

另请参阅:

List.listIterator(int)

descendingIterator

public Iterator<E> descendingIterator()

从接口复制的说明: Deque

Returns an iterator over the elements in this deque in reverse sequential order. The elements will be returned in order from last (tail) to first (head).

指定者:

descendingIterator 在接口中 Deque<E>

返回:

an iterator over the elements in this deque in reverse sequence

从以下版本开始:

1.6

clone

public Object clone()

Returns a shallow copy of this LinkedList. (The elements themselves are not cloned.)

覆盖:

clone 在类中 Object

返回:

a shallow copy of this LinkedList instance

另请参阅:

Cloneable

toArray

public Object[] toArray()

Returns an array containing all of the elements in this list in proper sequence (from first to last element).

The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.

This method acts as bridge between array-based and collection-based APIs.

指定者:

toArray 在接口中 Collection<E>

指定者:

toArray 在接口中 List<E>

覆盖:

toArray 在类中 AbstractCollection<E>

返回:

an array containing all of the elements in this list in proper sequence

另请参阅:

Arrays.asList(Object[])

toArray

public <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. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.

If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the list is set to null. (This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.)

Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.

Suppose x is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array of String:

     String[] y = x.toArray(new String[0]);

Note that toArray(new Object[0]) is identical in function to toArray().

指定者:

toArray 在接口中 Collection<E>

指定者:

toArray 在接口中 List<E>

覆盖:

toArray 在类中 AbstractCollection<E>

类型参数:

T - the runtime type of the array to contain the collection

参数:

a - the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

返回:

an array containing the elements of the list

抛出:

ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list

NullPointerException - if the specified array is null

spliterator

public Spliterator<E> spliterator()

Creates a late-binding and fail-fast Spliterator over the elements in this list.

The Spliterator reports Spliterator#SIZED and Spliterator#ORDERED. Overriding implementations should document the reporting of additional characteristic values.

指定者:

spliterator 在接口中 Collection<E>

指定者:

spliterator 在接口中 Iterable<E>

指定者:

spliterator 在接口中 List<E>

返回:

a Spliterator over the elements in this list

从以下版本开始:

1.8