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Préférences
Moteurs de recherche
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JavaTM 2 Platform Std. Ed. v1.6.0
java.util
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Constructor Summary | |
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PriorityQueue()
Creates a PriorityQueue with the default initial
capacity (11) that orders its elements according to their
natural ordering. |
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PriorityQueue(Collection<? extends E> c)
Creates a PriorityQueue containing the elements in the
specified collection. |
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PriorityQueue(int initialCapacity)
Creates a PriorityQueue with the specified initial
capacity that orders its elements according to their
natural ordering. |
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PriorityQueue(int initialCapacity,
Comparator<? super E> comparator)
Creates a PriorityQueue with the specified initial capacity
that orders its elements according to the specified comparator. |
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PriorityQueue(PriorityQueue<? extends E> c)
Creates a PriorityQueue containing the elements in the
specified priority queue. |
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PriorityQueue(SortedSet<? extends E> c)
Creates a PriorityQueue containing the elements in the
specified sorted set. |
Method Summary | ||
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boolean |
add(E e)
Inserts the specified element into this priority queue. |
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void |
clear()
Removes all of the elements from this priority queue. |
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Comparator<? super E> |
comparator()
Returns the comparator used to order the elements in this queue, or null if this queue is sorted according to
the natural ordering of its elements. |
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boolean |
contains(Object o)
Returns true if this queue contains the specified element. |
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Iterator<E> |
iterator()
Returns an iterator over the elements in this queue. |
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boolean |
offer(E e)
Inserts the specified element into this priority queue. |
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E |
peek()
Retrieves, but does not remove, the head of this queue, or returns null if this queue is empty. |
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E |
poll()
Retrieves and removes the head of this queue, or returns null if this queue is empty. |
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boolean |
remove(Object o)
Removes a single instance of the specified element from this queue, if it is present. |
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int |
size()
Returns the number of elements in this collection. |
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Object[] |
toArray()
Returns an array containing all of the elements in this queue. |
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toArray(T[] a)
Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. |
Methods inherited from class java.util.AbstractQueue |
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addAll, element, remove |
Methods inherited from class java.util.AbstractCollection |
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containsAll, isEmpty, removeAll, retainAll, toString |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface java.util.Collection |
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containsAll, equals, hashCode, isEmpty, removeAll, retainAll |
Constructor Detail |
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public PriorityQueue()
PriorityQueue
with the default initial
capacity (11) that orders its elements according to their
natural ordering.
public PriorityQueue(int initialCapacity)
PriorityQueue
with the specified initial
capacity that orders its elements according to their
natural ordering.
initialCapacity
- the initial capacity for this priority queue
IllegalArgumentException
- if initialCapacity
is less
than 1public PriorityQueue(int initialCapacity, Comparator<? super E> comparator)
PriorityQueue
with the specified initial capacity
that orders its elements according to the specified comparator.
initialCapacity
- the initial capacity for this priority queuecomparator
- the comparator that will be used to order this
priority queue. If null
, the natural ordering of the elements will be used.
IllegalArgumentException
- if initialCapacity
is
less than 1public PriorityQueue(Collection<? extends E> c)
PriorityQueue
containing the elements in the
specified collection. If the specified collection is an instance of
a SortedSet
or is another PriorityQueue
, this
priority queue will be ordered according to the same ordering.
Otherwise, this priority queue will be ordered according to the
natural ordering of its elements.
c
- the collection whose elements are to be placed
into this priority queue
ClassCastException
- if elements of the specified collection
cannot be compared to one another according to the priority
queue's ordering
NullPointerException
- if the specified collection or any
of its elements are nullpublic PriorityQueue(PriorityQueue<? extends E> c)
PriorityQueue
containing the elements in the
specified priority queue. This priority queue will be
ordered according to the same ordering as the given priority
queue.
c
- the priority queue whose elements are to be placed
into this priority queue
ClassCastException
- if elements of c
cannot be
compared to one another according to c
's
ordering
NullPointerException
- if the specified priority queue or any
of its elements are nullpublic PriorityQueue(SortedSet<? extends E> c)
PriorityQueue
containing the elements in the
specified sorted set. This priority queue will be ordered
according to the same ordering as the given sorted set.
c
- the sorted set whose elements are to be placed
into this priority queue
ClassCastException
- if elements of the specified sorted
set cannot be compared to one another according to the
sorted set's ordering
NullPointerException
- if the specified sorted set or any
of its elements are nullMethod Detail |
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public boolean add(E e)
add
in interface Collection<E>
add
in interface Queue<E>
add
in class AbstractQueue<E>
e
- the element to add
true
(as specified by Collection.add(E)
)
ClassCastException
- if the specified element cannot be
compared with elements currently in this priority queue
according to the priority queue's ordering
NullPointerException
- if the specified element is nullpublic boolean offer(E e)
e
- the element to add
true
(as specified by Queue.offer(E)
)
ClassCastException
- if the specified element cannot be
compared with elements currently in this priority queue
according to the priority queue's ordering
NullPointerException
- if the specified element is nullpublic E peek()
Queue
public boolean remove(Object o)
e
such
that o.equals(e)
, if this queue contains one or more such
elements. Returns true
if and only if this queue contained
the specified element (or equivalently, if this queue changed as a
result of the call).
remove
in interface Collection<E>
remove
in class AbstractCollection<E>
o
- element to be removed from this queue, if present
true
if this queue changed as a result of the callpublic boolean contains(Object o)
true
if this queue contains the specified element.
More formally, returns true
if and only if this queue contains
at least one element e
such that o.equals(e)
.
contains
in interface Collection<E>
contains
in class AbstractCollection<E>
o
- object to be checked for containment in this queue
true
if this queue contains the specified elementpublic Object[] toArray()
The returned array will be "safe" in that no references to it are maintained by this queue. (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 the queue fits in the specified array with room to spare
(i.e., the array has more elements than the queue), the element in
the array immediately following the end of the collection 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 queue known to contain only strings. The following code can be used to dump the queue 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 queue 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 queue
NullPointerException
- if the specified array is nullpublic Iterator<E> iterator()
iterator
in interface Iterable<E>
iterator
in interface Collection<E>
iterator
in class AbstractCollection<E>
public int size()
Collection
size
in interface Collection<E>
size
in class AbstractCollection<E>
public void clear()
clear
in interface Collection<E>
clear
in class AbstractQueue<E>
public E poll()
Queue
public Comparator<? super E> comparator()
null
if this queue is sorted according to
the natural ordering of its elements.
null
if this queue is sorted according to the
natural ordering of its elements