public class ObjectHeapPriorityQueue<K> extends AbstractPriorityQueue<K>
Instances of this class represent a priority queue using a heap. The heap is enlarged as needed, but
it is never shrunk. Use the trim()
method to reduce its size, if necessary.
Constructor and Description |
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ObjectHeapPriorityQueue()
Creates a new empty queue using the natural order.
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ObjectHeapPriorityQueue(java.util.Collection<? extends K> collection)
Creates a queue using the elements in a collection using the natural order.
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ObjectHeapPriorityQueue(java.util.Collection<? extends K> collection,
java.util.Comparator<? super K> c)
Creates a queue using the elements in a collection using a given comparator.
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ObjectHeapPriorityQueue(java.util.Comparator<? super K> c)
Creates a new empty queue with a given comparator.
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ObjectHeapPriorityQueue(int capacity)
Creates a new empty queue with a given capacity and using the natural order.
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ObjectHeapPriorityQueue(int capacity,
java.util.Comparator<? super K> c)
Creates a new empty queue with a given capacity and comparator.
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ObjectHeapPriorityQueue(K[] a)
Wraps a given array in a queue using the natural order.
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ObjectHeapPriorityQueue(K[] a,
java.util.Comparator<? super K> c)
Wraps a given array in a queue using a given comparator.
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ObjectHeapPriorityQueue(K[] a,
int size)
Wraps a given array in a queue using the natural order.
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ObjectHeapPriorityQueue(K[] a,
int size,
java.util.Comparator<? super K> c)
Wraps a given array in a queue using a given comparator.
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Modifier and Type | Method and Description |
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void |
changed()
Notifies the queue that the first element has changed (optional operation).
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void |
clear()
Removes all elements from this queue.
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java.util.Comparator<? super K> |
comparator()
Returns the comparator associated with this queue, or
null if it uses its elements' natural ordering. |
K |
dequeue()
Dequeues the first element from the queue.
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void |
enqueue(K x)
Enqueues a new element.
|
K |
first()
Returns the first element of the queue.
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int |
size()
Returns the number of elements in this queue.
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void |
trim()
Trims the underlying heap array so that it has exactly
size() elements. |
isEmpty, last
public ObjectHeapPriorityQueue(int capacity, java.util.Comparator<? super K> c)
capacity
- the initial capacity of this queue.c
- the comparator used in this queue, or null
for the natural order.public ObjectHeapPriorityQueue(int capacity)
capacity
- the initial capacity of this queue.public ObjectHeapPriorityQueue(java.util.Comparator<? super K> c)
c
- the comparator used in this queue, or null
for the natural order.public ObjectHeapPriorityQueue()
public ObjectHeapPriorityQueue(K[] a, int size, java.util.Comparator<? super K> c)
The queue returned by this method will be backed by the given array.
The first size
element of the array will be rearranged so to form a heap (this is
more efficient than enqueing the elements of a
one by one).
a
- an array.size
- the number of elements to be included in the queue.c
- the comparator used in this queue, or null
for the natural order.public ObjectHeapPriorityQueue(K[] a, java.util.Comparator<? super K> c)
The queue returned by this method will be backed by the given array.
The elements of the array will be rearranged so to form a heap (this is
more efficient than enqueing the elements of a
one by one).
a
- an array.c
- the comparator used in this queue, or null
for the natural order.public ObjectHeapPriorityQueue(K[] a, int size)
The queue returned by this method will be backed by the given array.
The first size
element of the array will be rearranged so to form a heap (this is
more efficient than enqueing the elements of a
one by one).
a
- an array.size
- the number of elements to be included in the queue.public ObjectHeapPriorityQueue(K[] a)
The queue returned by this method will be backed by the given array.
The elements of the array will be rearranged so to form a heap (this is
more efficient than enqueing the elements of a
one by one).
a
- an array.public ObjectHeapPriorityQueue(java.util.Collection<? extends K> collection, java.util.Comparator<? super K> c)
This constructor is more efficient than enqueing the elements of collection
one by one.
collection
- a collection; its elements will be used to initialize the queue.c
- the comparator used in this queue, or null
for the natural order.public ObjectHeapPriorityQueue(java.util.Collection<? extends K> collection)
This constructor is
more efficient than enqueing the elements of collection
one by one.
collection
- a collection; its elements will be used to initialize the queue.public void enqueue(K x)
PriorityQueue
x
- the element to enqueue..public K dequeue()
PriorityQueue
public K first()
PriorityQueue
public void changed()
PriorityQueue
changed
in interface PriorityQueue<K>
changed
in class AbstractPriorityQueue<K>
public int size()
PriorityQueue
public void clear()
PriorityQueue
public void trim()
size()
elements.public java.util.Comparator<? super K> comparator()
PriorityQueue
null
if it uses its elements' natural ordering.null
if it uses its elements' natural ordering.