CITS2200
Interface PriorityQueue<E>

public interface PriorityQueue<E>

PriorityQueue interface.

Method Summary

E	dequeue() remove the item at the front of the queue (the element with the highest priority that has been there the longest)
void	enqueue(E a, int priority) insert an item at the back into the queue with a given priority
E	examine() examine the item at the front of the queue (the element with the highest priority that has been in the queue the longest)
boolean	isEmpty() test whether the queue is empty
Iterator	iterator() return a DAT.Iterator to examine all the elements in the PriorityQueue

Method Detail

isEmpty

boolean isEmpty()

test whether the queue is empty

Returns:

true if the prioirty queue is empty, false otherwise

enqueue

void enqueue(E a,
             int priority)
             throws IllegalValue

insert an item at the back into the queue with a given priority

Parameters:

a - the item to insert

priority - the priority of the element

Throws:

IllegalValue - if the priority is not in a valid range

examine

E examine()
          throws Underflow

examine the item at the front of the queue (the element with the highest priority that has been in the queue the longest)

Returns:

the first item,

Throws:

Underflow - if the queue is empty

dequeue

E dequeue()
          throws Underflow

remove the item at the front of the queue (the element with the highest priority that has been there the longest)

Returns:

the removed item

Throws:

Underflow - if the queue is empty

iterator

Iterator iterator()

return a DAT.Iterator to examine all the elements in the PriorityQueue

Returns:

an Iterator pointing to before the first item