|
||||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
java.lang.Objectjava.util.AbstractCollection
edu.emory.mathcs.backport.java.util.AbstractCollection
edu.emory.mathcs.backport.java.util.ArrayDeque
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(java.util.Collection 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(java.lang.Object e)
Inserts the specified element at the end of this deque. |
void |
addFirst(java.lang.Object e)
Inserts the specified element at the front of this deque. |
void |
addLast(java.lang.Object e)
Inserts the specified element at the end of this deque. |
void |
clear()
Removes all of the elements from this deque. |
java.lang.Object |
clone()
Returns a copy of this deque. |
boolean |
contains(java.lang.Object o)
Returns true if this deque contains the specified element. |
java.util.Iterator |
descendingIterator()
Returns an iterator over the elements in this deque in reverse sequential order. |
java.lang.Object |
element()
Retrieves, but does not remove, the head of the queue represented by this deque. |
java.lang.Object |
getFirst()
Retrieves, but does not remove, the first element of this deque. |
java.lang.Object |
getLast()
Retrieves, but does not remove, the last element of this deque. |
boolean |
isEmpty()
Returns true if this deque contains no elements. |
java.util.Iterator |
iterator()
Returns an iterator over the elements in this deque. |
boolean |
offer(java.lang.Object e)
Inserts the specified element at the end of this deque. |
boolean |
offerFirst(java.lang.Object e)
Inserts the specified element at the front of this deque. |
boolean |
offerLast(java.lang.Object e)
Inserts the specified element at the end of this deque. |
java.lang.Object |
peek()
Retrieves, but does not remove, the head of the queue represented by this deque, or returns null if this deque is empty. |
java.lang.Object |
peekFirst()
Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty. |
java.lang.Object |
peekLast()
Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty. |
java.lang.Object |
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. |
java.lang.Object |
pollFirst()
Retrieves and removes the first element of this deque, or returns null if this deque is empty. |
java.lang.Object |
pollLast()
Retrieves and removes the last element of this deque, or returns null if this deque is empty. |
java.lang.Object |
pop()
Pops an element from the stack represented by this deque. |
void |
push(java.lang.Object e)
Pushes an element onto the stack represented by this deque. |
java.lang.Object |
remove()
Retrieves and removes the head of the queue represented by this deque. |
boolean |
remove(java.lang.Object o)
Removes a single instance of the specified element from this deque. |
java.lang.Object |
removeFirst()
Retrieves and removes the first element of this deque. |
boolean |
removeFirstOccurrence(java.lang.Object o)
Removes the first occurrence of the specified element in this deque (when traversing the deque from head to tail). |
java.lang.Object |
removeLast()
Retrieves and removes the last element of this deque. |
boolean |
removeLastOccurrence(java.lang.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. |
java.lang.Object[] |
toArray()
Returns an array containing all of the elements in this deque in proper sequence (from first to last element). |
java.lang.Object[] |
toArray(java.lang.Object[] 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(java.util.Collection c)
c - the collection whose elements are to be placed into the deque
java.lang.NullPointerException - if the specified collection is null| Method Detail |
public void addFirst(java.lang.Object e)
addFirst in interface Dequee - the element to add
java.lang.NullPointerException - if the specified element is nullpublic void addLast(java.lang.Object e)
This method is equivalent to add(java.lang.Object).
addLast in interface Dequee - the element to add
java.lang.NullPointerException - if the specified element is nullpublic boolean offerFirst(java.lang.Object e)
offerFirst in interface Dequee - the element to add
Deque.offerFirst(java.lang.Object))
java.lang.NullPointerException - if the specified element is nullpublic boolean offerLast(java.lang.Object e)
offerLast in interface Dequee - the element to add
Deque.offerLast(java.lang.Object))
java.lang.NullPointerException - if the specified element is nullpublic java.lang.Object removeFirst()
DequepollFirst only in that it throws an
exception if this deque is empty.
removeFirst in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object removeLast()
DequepollLast only in that it throws an
exception if this deque is empty.
removeLast in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object pollFirst()
Deque
pollFirst in interface Dequepublic java.lang.Object pollLast()
Deque
pollLast in interface Dequepublic java.lang.Object getFirst()
DequepeekFirst only in that it
throws an exception if this deque is empty.
getFirst in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object getLast()
DequepeekLast only in that it
throws an exception if this deque is empty.
getLast in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object peekFirst()
Deque
peekFirst in interface Dequepublic java.lang.Object peekLast()
Deque
peekLast in interface Dequepublic boolean removeFirstOccurrence(java.lang.Object o)
removeFirstOccurrence in interface Dequeo - element to be removed from this deque, if present
public boolean removeLastOccurrence(java.lang.Object o)
removeLastOccurrence in interface Dequeo - element to be removed from this deque, if present
public boolean add(java.lang.Object e)
This method is equivalent to addLast(java.lang.Object).
add in interface Dequee - the element to add
Collection.add(java.lang.Object))
java.lang.NullPointerException - if the specified element is nullpublic boolean offer(java.lang.Object e)
This method is equivalent to offerLast(java.lang.Object).
offer in interface Dequee - the element to add
Queue.offer(java.lang.Object))
java.lang.NullPointerException - if the specified element is nullpublic java.lang.Object remove()
poll only in that it throws an
exception if this deque is empty.
This method is equivalent to removeFirst().
remove in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object poll()
This method is equivalent to pollFirst().
poll in interface Dequepublic java.lang.Object element()
peek only in
that it throws an exception if this deque is empty.
This method is equivalent to getFirst().
element in interface Dequejava.util.NoSuchElementExceptionpublic java.lang.Object peek()
This method is equivalent to peekFirst().
peek in interface Dequepublic void push(java.lang.Object e)
This method is equivalent to addFirst(java.lang.Object).
push in interface Dequee - the element to push
java.lang.NullPointerException - if the specified element is nullpublic java.lang.Object pop()
This method is equivalent to removeFirst().
pop in interface Dequejava.util.NoSuchElementExceptionpublic int size()
size in interface Dequepublic boolean isEmpty()
isEmpty in interface java.util.Collectionpublic java.util.Iterator iterator()
remove() or popped (via successive calls to pop()).
iterator in interface Dequepublic java.util.Iterator descendingIterator()
Deque
descendingIterator in interface Dequepublic boolean contains(java.lang.Object o)
contains in interface Dequeo - object to be checked for containment in this deque
public boolean remove(java.lang.Object o)
This method is equivalent to removeFirstOccurrence(java.lang.Object).
remove in interface Dequeo - element to be removed from this deque, if present
public void clear()
clear in interface java.util.Collectionpublic java.lang.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 java.util.CollectiontoArray in class AbstractCollectionpublic java.lang.Object[] toArray(java.lang.Object[] 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 java.util.CollectiontoArray in class AbstractCollectiona - 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
java.lang.ArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this deque
java.lang.NullPointerException - if the specified array is nullpublic java.lang.Object clone()
|
||||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||