Package it.unimi.dsi.fastutil.objects

Class ObjectHeapPriorityQueue<K>

java.lang.Object

it.unimi.dsi.fastutil.objects.ObjectHeapPriorityQueue<K>

All Implemented Interfaces:

PriorityQueue<K>, Serializable

public class ObjectHeapPriorityQueue<K>
extends Object
implements PriorityQueue<K>, Serializable

A type-specific heap-based priority queue.

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.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
ObjectHeapPriorityQueue()	Creates a new empty queue using the natural order.
ObjectHeapPriorityQueue(int capacity)	Creates a new empty queue with a given capacity and using the natural order.
ObjectHeapPriorityQueue(int capacity, Comparator<? super K> c)	Creates a new empty queue with a given capacity and comparator.
ObjectHeapPriorityQueue(Collection<? extends K> collection)	Creates a queue using the elements in a collection using the natural order.
ObjectHeapPriorityQueue(Collection<? extends K> collection, Comparator<? super K> c)	Creates a queue using the elements in a collection using a given comparator.
ObjectHeapPriorityQueue(Comparator<? super K> c)	Creates a new empty queue with a given comparator.
ObjectHeapPriorityQueue(K[] a)	Wraps a given array in a queue using the natural order.
ObjectHeapPriorityQueue(K[] a, int size)	Wraps a given array in a queue using the natural order.
ObjectHeapPriorityQueue(K[] a, int size, Comparator<? super K> c)	Wraps a given array in a queue using a given comparator.
ObjectHeapPriorityQueue(K[] a, Comparator<? super K> c)	Wraps a given array in a queue using a given comparator.

Method Summary

Modifier and Type	Method	Description
void	changed()	Notifies the queue that the first element has changed (optional operation).
void	clear()	Removes all elements from this queue.
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.
void	enqueue(K x)	Enqueues a new element.
K	first()	Returns the first element of the queue.
int	size()	Returns the number of elements in this queue.
void	trim()	Trims the underlying heap array so that it has exactly size() elements.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.PriorityQueue

isEmpty, last

Constructor Detail

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(int capacity,
                               Comparator<? super K> c)

Creates a new empty queue with a given capacity and comparator.

Parameters:

capacity - the initial capacity of this queue.

c - the comparator used in this queue, or null for the natural order.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(int capacity)

Creates a new empty queue with a given capacity and using the natural order.

Parameters:

capacity - the initial capacity of this queue.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(Comparator<? super K> c)

Creates a new empty queue with a given comparator.

Parameters:

c - the comparator used in this queue, or null for the natural order.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue()

Creates a new empty queue using the natural order.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(K[] a,
                               int size,
                               Comparator<? super K> c)

Wraps a given array in a queue using a given comparator.

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).

Parameters:

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.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(K[] a,
                               Comparator<? super K> c)

Wraps a given array in a queue using a given comparator.

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).

Parameters:

a - an array.

c - the comparator used in this queue, or null for the natural order.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(K[] a,
                               int size)

Wraps a given array in a queue using the natural order.

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).

Parameters:

a - an array.

size - the number of elements to be included in the queue.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(K[] a)

Wraps a given array in a queue using the natural order.

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).

Parameters:

a - an array.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(Collection<? extends K> collection,
                               Comparator<? super K> c)

Creates a queue using the elements in a collection using a given comparator.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

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.

ObjectHeapPriorityQueue

public ObjectHeapPriorityQueue(Collection<? extends K> collection)

Creates a queue using the elements in a collection using the natural order.

This constructor is more efficient than enqueing the elements of collection one by one.

Parameters:

collection - a collection; its elements will be used to initialize the queue.

Method Detail

enqueue

public void enqueue(K x)

Description copied from interface: PriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface PriorityQueue<K>

Parameters:

x - the element to enqueue.

dequeue

public K dequeue()

Description copied from interface: PriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeue in interface PriorityQueue<K>

Returns:

the dequeued element.

first

public K first()

Description copied from interface: PriorityQueue

Returns the first element of the queue.

Specified by:

first in interface PriorityQueue<K>

Returns:

the first element.

changed

public void changed()

Description copied from interface: PriorityQueue

Notifies the queue that the first element has changed (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

changed in interface PriorityQueue<K>

size

public int size()

Description copied from interface: PriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface PriorityQueue<K>

Returns:

the number of elements in this queue.

clear

public void clear()

Description copied from interface: PriorityQueue

Removes all elements from this queue.

Specified by:

clear in interface PriorityQueue<K>

trim

public void trim()

Trims the underlying heap array so that it has exactly size() elements.

comparator

public Comparator<? super K> comparator()

Description copied from interface: PriorityQueue

Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.

Specified by:

comparator in interface PriorityQueue<K>

Returns:

the comparator associated with this sorted set, or null if it uses its elements' natural ordering.