|
Java™ Platform Standard Ed. 6 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
java.lang.Objectjava.util.AbstractCollection<E>
java.util.ArrayDeque<E>
E - the type of elements held in this collectionpublic class ArrayDeque<E>
Resizable-array implementation of the Deque interface. Array
deques have no capacity restrictions; they grow as necessary to support
usage. They are not thread-safe; in the absence of external
synchronization, they do not support concurrent access by multiple threads.
Null elements are prohibited. This class is likely to be faster than
Stack when used as a stack, and faster than LinkedList
when used as a queue.
Most ArrayDeque operations run in amortized constant time.
Exceptions include remove, removeFirstOccurrence, removeLastOccurrence, contains, iterator.remove(), and the bulk operations, all of which run in linear
time.
The iterators returned by this class's iterator method are
fail-fast: If the deque is modified at any time after the iterator
is created, in any way except through the iterator's own remove
method, the iterator will generally 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 and its iterator implement all of the
optional methods of the Collection and Iterator interfaces.
This class is a member of the Java Collections Framework.
| Constructor Summary | |
|---|---|
ArrayDeque()
Constructs an empty array deque with an initial capacity sufficient to hold 16 elements. |
|
ArrayDeque(Collection<? extends E> c)
Constructs a deque containing the elements of the specified collection, in the order they are returned by the collection's iterator. |
|
ArrayDeque(int numElements)
Constructs an empty array deque with an initial capacity sufficient to hold the specified number of elements. |
|
| Method Summary | ||
|---|---|---|
boolean |
add(E e)
Inserts the specified element at the end of this deque. |
|
void |
addFirst(E e)
Inserts the specified element at the front of this deque. |
|
void |
addLast(E e)
Inserts the specified element at the end of this deque. |
|
void |
clear()
Removes all of the elements from this deque. |
|
ArrayDeque<E> |
clone()
Returns a copy of this deque. |
|
boolean |
contains(Object o)
Returns true if this deque 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 of the queue represented by this deque. |
|
E |
getFirst()
Retrieves, but does not remove, the first element of this deque. |
|
E |
getLast()
Retrieves, but does not remove, the last element of this deque. |
|
boolean |
isEmpty()
Returns true if this deque contains no elements. |
|
Iterator<E> |
iterator()
Returns an iterator over the elements in this deque. |
|
boolean |
offer(E e)
Inserts the specified element at the end of this deque. |
|
boolean |
offerFirst(E e)
Inserts the specified element at the front of this deque. |
|
boolean |
offerLast(E e)
Inserts the specified element at the end of this deque. |
|
E |
peek()
Retrieves, but does not remove, the head of the queue represented by this deque, or returns null if this deque is empty. |
|
E |
peekFirst()
Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty. |
|
E |
peekLast()
Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty. |
|
E |
poll()
Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty. |
|
E |
pollFirst()
Retrieves and removes the first element of this deque, or returns null if this deque is empty. |
|
E |
pollLast()
Retrieves and removes the last element of this deque, or returns null if this deque is empty. |
|
E |
pop()
Pops an element from the stack represented by this deque. |
|
void |
push(E e)
Pushes an element onto the stack represented by this deque. |
|
E |
remove()
Retrieves and removes the head of the queue represented by this deque. |
|
boolean |
remove(Object o)
Removes a single instance of the specified element from this deque. |
|
E |
removeFirst()
Retrieves and removes the first element of this deque. |
|
boolean |
removeFirstOccurrence(Object o)
Removes the first occurrence of the specified element in this deque (when traversing the deque from head to tail). |
|
E |
removeLast()
Retrieves and removes the last element of this deque. |
|
boolean |
removeLastOccurrence(Object o)
Removes the last occurrence of the specified element in this deque (when traversing the deque from head to tail). |
|
int |
size()
Returns the number of elements in this deque. |
|
Object[] |
toArray()
Returns an array containing all of the elements in this deque in proper sequence (from first to last element). |
|
|
toArray(T[] a)
Returns an array containing all of the elements in this deque 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.AbstractCollection |
|---|
addAll, containsAll, removeAll, retainAll, toString |
| Methods inherited from class java.lang.Object |
|---|
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface java.util.Collection |
|---|
addAll, containsAll, equals, hashCode, removeAll, retainAll |
| Constructor Detail |
|---|
public ArrayDeque()
public ArrayDeque(int numElements)
numElements - lower bound on initial capacity of the dequepublic ArrayDeque(Collection<? extends E> c)
c - the collection whose elements are to be placed into the deque
NullPointerException - if the specified collection is null| Method Detail |
|---|
public void addFirst(E e)
addFirst in interface Deque<E>e - the element to add
NullPointerException - if the specified element is nullpublic void addLast(E e)
This method is equivalent to add(E).
addLast in interface Deque<E>e - the element to add
NullPointerException - if the specified element is nullpublic boolean offerFirst(E e)
offerFirst in interface Deque<E>e - the element to add
Deque.offerFirst(E))
NullPointerException - if the specified element is nullpublic boolean offerLast(E e)
offerLast in interface Deque<E>e - the element to add
Deque.offerLast(E))
NullPointerException - if the specified element is nullpublic E removeFirst()
DequepollFirst only in that it throws an
exception if this deque is empty.
removeFirst in interface Deque<E>NoSuchElementException - if this deque is emptypublic E removeLast()
DequepollLast only in that it throws an
exception if this deque is empty.
removeLast in interface Deque<E>NoSuchElementException - if this deque is emptypublic E pollFirst()
Deque
pollFirst in interface Deque<E>public E pollLast()
Deque
pollLast in interface Deque<E>public E getFirst()
DequepeekFirst only in that it
throws an exception if this deque is empty.
getFirst in interface Deque<E>NoSuchElementException - if this deque is emptypublic E getLast()
DequepeekLast only in that it
throws an exception if this deque is empty.
getLast in interface Deque<E>NoSuchElementException - if this deque is emptypublic E peekFirst()
Deque
peekFirst in interface Deque<E>public E peekLast()
Deque
peekLast in interface Deque<E>public boolean removeFirstOccurrence(Object o)
removeFirstOccurrence in interface Deque<E>o - element to be removed from this deque, if present
public boolean removeLastOccurrence(Object o)
removeLastOccurrence in interface Deque<E>o - element to be removed from this deque, if present
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 Queue<E>add in class AbstractCollection<E>e - the element to add
Collection.add(E))
NullPointerException - if the specified element is nullpublic boolean offer(E e)
This method is equivalent to offerLast(E).
offer in interface Deque<E>offer in interface Queue<E>e - the element to add
Queue.offer(E))
NullPointerException - if the specified element is nullpublic E remove()
poll only in that it throws an
exception if this deque is empty.
This method is equivalent to removeFirst().
remove in interface Deque<E>remove in interface Queue<E>NoSuchElementException - if this deque is emptypublic E poll()
This method is equivalent to pollFirst().
poll in interface Deque<E>poll in interface Queue<E>public E element()
peek only in
that it throws an exception if this deque is empty.
This method is equivalent to getFirst().
element in interface Deque<E>element in interface Queue<E>NoSuchElementException - if this deque is emptypublic E peek()
This method is equivalent to peekFirst().
peek in interface Deque<E>peek in interface Queue<E>public void push(E e)
This method is equivalent to addFirst(E).
push in interface Deque<E>e - the element to push
NullPointerException - if the specified element is nullpublic E pop()
This method is equivalent to removeFirst().
pop in interface Deque<E>NoSuchElementException - if this deque is emptypublic int size()
size in interface Collection<E>size in interface Deque<E>size in class AbstractCollection<E>public boolean isEmpty()
isEmpty in interface Collection<E>isEmpty in class AbstractCollection<E>public Iterator<E> iterator()
remove() or popped (via successive calls to pop()).
iterator in interface Iterable<E>iterator in interface Collection<E>iterator in interface Deque<E>iterator in class AbstractCollection<E>public Iterator<E> descendingIterator()
Deque
descendingIterator in interface Deque<E>public boolean contains(Object o)
contains in interface Collection<E>contains in interface Deque<E>contains in class AbstractCollection<E>o - object to be checked for containment in this deque
public boolean remove(Object o)
This method is equivalent to removeFirstOccurrence(java.lang.Object).
remove in interface Collection<E>remove in interface Deque<E>remove in class AbstractCollection<E>o - element to be removed from this deque, if present
public void clear()
clear in interface Collection<E>clear in class AbstractCollection<E>public Object[] toArray()
The returned array will be "safe" in that no references to it are maintained by this deque. (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 class AbstractCollection<E>public <T> T[] toArray(T[] a)
If this deque fits in the specified array with room to spare (i.e., the array has more elements than this deque), the element in the array immediately following the end of the deque is set to null.
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 deque known to contain only strings. The following code can be used to dump the deque 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 class AbstractCollection<E>a - the array into which the elements of the deque 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 deque
NullPointerException - if the specified array is nullpublic ArrayDeque<E> clone()
clone in class ObjectCloneable
|
Java™ Platform Standard Ed. 6 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
Copyright © 1993, 2010, Oracle and/or its affiliates. All rights reserved.