Interface IPriorityQueue<E extends Comparable<? super E>>

All Superinterfaces:

IQueue<E>

All Known Implementing Classes:

Heap

public interface IPriorityQueue<E extends Comparable<? super E>>
extends IQueue<E>

A priority queue is different from a regular queue because it respects priority among the elements. The head of a priority queue is an element of greatest priority among all elements within the queue. The queue retrieval operations poll, remove, peek, and element access the element at the head of the queue.

Method Summary

Modifier and Type	Method and Description
default void	add(E item) Inserts the specified element into this queue, returning true upon success.
default E	element() Retrieves, but does not remove, the head of this queue.
default boolean	isEmpty() Returns true if this queue contains no elements.
boolean	offer(E e) Inserts the specified element into this queue.
E	peek() Retrieves, but does not remove, an element of greatest priority, which is the head of the priority queue.
E	poll() Retrieves and removes an element of greatest priority, which is the head of the priority queue.
default E	remove() Retrieves and removes the head of this queue.

Methods inherited from interface IQueue

clear, contains, size, toString

Method Detail

poll

E poll()

Retrieves and removes an element of greatest priority, which is the head of the priority queue. For example: A queue that prioritizes Strings by max length would return the longest String. A queue that prioritizes Integers by min value would return the minimum number.

Specified by:

poll in interface IQueue<E extends Comparable<? super E>>

Returns:

the element of greatest priority, or null if this queue is empty

peek

E peek()

Retrieves, but does not remove, an element of greatest priority, which is the head of the priority queue.

Specified by:

peek in interface IQueue<E extends Comparable<? super E>>

Returns:

the element of greatest priority, or null if this queue is empty

offer

boolean offer(E e)

Inserts the specified element into this queue.

Specified by:

offer in interface IQueue<E extends Comparable<? super E>>

Parameters:

e - the element to add

Returns:

true if the element was added to this priority queue, else false

add

default void add(E item)

Description copied from interface: IQueue

Inserts the specified element into this queue, returning true upon success.

This method throws an IllegalStateException if no space is available to hold the new item.

Specified by:

add in interface IQueue<E extends Comparable<? super E>>

Parameters:

item - the item to add

remove

default E remove()

Description copied from interface: IQueue

Retrieves and removes the head of this queue. This method differs from poll only in that it throws an exception if this queue is empty.

Specified by:

remove in interface IQueue<E extends Comparable<? super E>>

Returns:

the head of this queue

element

default E element()

Description copied from interface: IQueue

Retrieves, but does not remove, the head of this queue. This method differs from peek only in that it throws an exception if this queue is empty.

Specified by:

element in interface IQueue<E extends Comparable<? super E>>

Returns:

the head of this queue

isEmpty

default boolean isEmpty()

Description copied from interface: IQueue

Returns true if this queue contains no elements.

Specified by:

isEmpty in interface IQueue<E extends Comparable<? super E>>

Returns:

true if this queue is empty, false otherwise