org.apache.commons.collections
Interface PriorityQueue

All Known Implementing Classes:

BinaryHeap, SynchronizedPriorityQueue

public interface PriorityQueue

Interface for priority queues. This interface does not dictate whether it is min or max heap.

Since:

1.0

Author:

Peter Donald

Method Summary

void	clear() Clear all elements from queue.
void	insert(Object element) Insert an element into queue.
boolean	isEmpty() Test if queue is empty.
Object	peek() Return element on top of heap but don't remove it.
Object	pop() Return element on top of heap and remove it.

Method Detail

clear

public void clear()

Clear all elements from queue.

insert

public void insert(Object element)

Insert an element into queue.

Parameters:

element - the element to be inserted

Throws:

ClassCastException - if the specified element's type prevents it from being compared to other items in the queue to determine its relative priority.

isEmpty

public boolean isEmpty()

Test if queue is empty.

Returns:

true if queue is empty else false.

peek

public Object peek()
            throws NoSuchElementException

Return element on top of heap but don't remove it.

Returns:

the element at top of heap

Throws:

NoSuchElementException - if isEmpty() == true

pop

public Object pop()
           throws NoSuchElementException

Return element on top of heap and remove it.

Returns:

the element at top of heap

Throws:

NoSuchElementException - if isEmpty() == true