java.util.AbstractCollection<E>
java.util.AbstractList<E>
java.util.AbstractSequentialList<E>
java.util.LinkedList<E>
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Java™ Platform Standard Ed. 6 |
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java.lang.Object
E - the type of elements held in this collectionpublic class LinkedList<E>
Linked list implementation of the List interface. Implements all optional list operations, and permits all elements (including null). In addition to implementing the List interface, the LinkedList class provides uniformly named methods to get, remove and insert an element at the beginning and end of the list. These operations allow linked lists to be used as a stack, queue, or double-ended queue.
The class implements the Deque interface, providing first-in-first-out queue operations for add, poll, along with other stack and deque operations.
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.
List,
ArrayList,
Vector,
Serialized Form| Field Summary |
|---|
| Fields inherited from class java.util.AbstractList |
|---|
modCount |
| Constructor Summary | |
|---|---|
LinkedList()
Constructs an empty list. |
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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. |
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| Method Summary | ||
|---|---|---|
boolean |
add(E e)
Appends the specified element to the end of this list. |
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void |
add(int index,
E element)
Inserts the specified element at the specified position in this list. |
|
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. |
|
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. |
|
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. |
|
Object[] |
toArray()
Returns an array containing all of the elements in this list in proper sequence (from first to last element). |
|
|
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. |
|
| Methods inherited from class java.util.AbstractSequentialList |
|---|
iterator |
| Methods inherited from class java.util.AbstractList |
|---|
equals, hashCode, listIterator, removeRange, subList |
| Methods inherited from class java.util.AbstractCollection |
|---|
containsAll, isEmpty, removeAll, retainAll, toString |
| Methods inherited from class java.lang.Object |
|---|
finalize, getClass, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface java.util.List |
|---|
containsAll, equals, hashCode, isEmpty, iterator, listIterator, removeAll, retainAll, subList |
| Methods inherited from interface java.util.Deque |
|---|
iterator |
| Constructor Detail |
|---|
public LinkedList()
public LinkedList(Collection<? extends E> c)
c - the collection whose elements are to be placed into this list
NullPointerException - if the specified collection is null| Method Detail |
|---|
public E getFirst()
getFirst in interface Deque<E>NoSuchElementException - if this list is emptypublic E getLast()
getLast in interface Deque<E>NoSuchElementException - if this list is emptypublic E removeFirst()
removeFirst in interface Deque<E>NoSuchElementException - if this list is emptypublic E removeLast()
removeLast in interface Deque<E>NoSuchElementException - if this list is emptypublic void addFirst(E e)
addFirst in interface Deque<E>e - the element to addpublic void addLast(E e)
This method is equivalent to add(E).
addLast in interface Deque<E>e - the element to addpublic boolean contains(Object o)
contains in interface Collection<E>contains in interface Deque<E>contains in interface List<E>contains in class AbstractCollection<E>o - element whose presence in this list is to be tested
public int size()
size in interface Collection<E>size in interface Deque<E>size in interface List<E>size in class AbstractCollection<E>public boolean add(E e)
This method is equivalent to addLast(E).
add in interface Collection<E>add in interface Deque<E>add in interface List<E>add in interface Queue<E>add in class AbstractList<E>e - element to be appended to this list
Collection.add(E))public boolean remove(Object o)
remove in interface Collection<E>remove in interface Deque<E>remove in interface List<E>remove in class AbstractCollection<E>o - element to be removed from this list, if present
public boolean addAll(Collection<? extends E> c)
addAll in interface Collection<E>addAll in interface List<E>addAll in class AbstractCollection<E>c - collection containing elements to be added to this list
NullPointerException - if the specified collection is nullAbstractCollection.add(Object)
public boolean addAll(int index,
Collection<? extends E> c)
addAll in interface List<E>addAll in class AbstractSequentialList<E>index - index at which to insert the first element
from the specified collectionc - collection containing elements to be added to this list
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())
NullPointerException - if the specified collection is nullpublic void clear()
clear in interface Collection<E>clear in interface List<E>clear in class AbstractList<E>public E get(int index)
get in interface List<E>get in class AbstractSequentialList<E>index - index of the element to return
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())
public E set(int index,
E element)
set in interface List<E>set in class AbstractSequentialList<E>index - index of the element to replaceelement - element to be stored at the specified position
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())
public void add(int index,
E element)
add in interface List<E>add in class AbstractSequentialList<E>index - index at which the specified element is to be insertedelement - element to be inserted
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())public E remove(int index)
remove in interface List<E>remove in class AbstractSequentialList<E>index - the index of the element to be removed
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())public int indexOf(Object o)
indexOf in interface List<E>indexOf in class AbstractList<E>o - element to search for
public int lastIndexOf(Object o)
lastIndexOf in interface List<E>lastIndexOf in class AbstractList<E>o - element to search for
public E peek()
peek in interface Deque<E>peek in interface Queue<E>public E element()
element in interface Deque<E>element in interface Queue<E>NoSuchElementException - if this list is emptypublic E poll()
poll in interface Deque<E>poll in interface Queue<E>public E remove()
remove in interface Deque<E>remove in interface Queue<E>NoSuchElementException - if this list is emptypublic boolean offer(E e)
offer in interface Deque<E>offer in interface Queue<E>e - the element to add
Queue.offer(E))public boolean offerFirst(E e)
offerFirst in interface Deque<E>e - the element to insert
Deque.offerFirst(E))public boolean offerLast(E e)
offerLast in interface Deque<E>e - the element to insert
Deque.offerLast(E))public E peekFirst()
peekFirst in interface Deque<E>public E peekLast()
peekLast in interface Deque<E>public E pollFirst()
pollFirst in interface Deque<E>public E pollLast()
pollLast in interface Deque<E>public void push(E e)
This method is equivalent to addFirst(E).
push in interface Deque<E>e - the element to pushpublic E pop()
This method is equivalent to removeFirst().
pop in interface Deque<E>NoSuchElementException - if this list is emptypublic boolean removeFirstOccurrence(Object o)
removeFirstOccurrence in interface Deque<E>o - element to be removed from this list, if present
public boolean removeLastOccurrence(Object o)
removeLastOccurrence in interface Deque<E>o - element to be removed from this list, if present
public ListIterator<E> listIterator(int index)
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.
listIterator in interface List<E>listIterator in class AbstractSequentialList<E>index - index of the first element to be returned from the
list-iterator (by a call to next)
IndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())List.listIterator(int)public Iterator<E> descendingIterator()
Deque
descendingIterator in interface Deque<E>public Object clone()
clone in class ObjectCloneablepublic Object[] toArray()
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.
toArray in interface Collection<E>toArray in interface List<E>toArray in class AbstractCollection<E>Arrays.asList(Object[])public <T> T[] toArray(T[] a)
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().
toArray in interface Collection<E>toArray in interface List<E>toArray in class AbstractCollection<E>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.
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
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Java™ Platform Standard Ed. 6 |
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