Package it.unimi.dsi.fastutil

Class PriorityQueues.EmptyPriorityQueue

java.lang.Object

it.unimi.dsi.fastutil.PriorityQueues.EmptyPriorityQueue

All Implemented Interfaces:

PriorityQueue, java.io.Serializable

Enclosing class:

PriorityQueues

public static class PriorityQueues.EmptyPriorityQueue
extends java.lang.Object
implements PriorityQueue, java.io.Serializable

An immutable class representing the empty priority queue.

This class may be useful to implement your own in case you subclass PriorityQueue.

See Also:

Serialized Form

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.
java.lang.Object	clone()
java.util.Comparator<?>	comparator()	Returns the comparator associated with this queue, or null if it uses its elements' natural ordering.
java.lang.Object	dequeue()	Dequeues the first element from the queue.
void	enqueue(java.lang.Object o)	Enqueues a new element.
boolean	equals(java.lang.Object o)
java.lang.Object	first()	Returns the first element of the queue.
int	hashCode()
boolean	isEmpty()	Checks whether this queue is empty.
java.lang.Object	last()	Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).
int	size()	Returns the number of elements in this queue.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

enqueue

public void enqueue(java.lang.Object o)

Description copied from interface: PriorityQueue

Enqueues a new element.

Specified by:

enqueue in interface PriorityQueue

Parameters:

o - the element to enqueue.

dequeue

public java.lang.Object dequeue()

Description copied from interface: PriorityQueue

Dequeues the first element from the queue.

Specified by:

dequeue in interface PriorityQueue

Returns:

the dequeued element.

isEmpty

public boolean isEmpty()

Description copied from interface: PriorityQueue

Checks whether this queue is empty.

This default implementation checks whether PriorityQueue.size() is zero.

Specified by:

isEmpty in interface PriorityQueue

Returns:

true if this queue is empty.

size

public int size()

Description copied from interface: PriorityQueue

Returns the number of elements in this queue.

Specified by:

size in interface PriorityQueue

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

first

public java.lang.Object first()

Description copied from interface: PriorityQueue

Returns the first element of the queue.

Specified by:

first in interface PriorityQueue

Returns:

the first element.

last

public java.lang.Object last()

Description copied from interface: PriorityQueue

Returns the last element of the queue, that is, the element the would be dequeued last (optional operation).

This default implementation just throws an UnsupportedOperationException.

Specified by:

last in interface PriorityQueue

Returns:

the last 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

comparator

public java.util.Comparator<?> 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

Returns:

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

clone

public java.lang.Object clone()

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object