structure5
Interface PriorityQueue<E extends java.lang.Comparable<E>>

All Known Subinterfaces:

MergeableHeap<E>

All Known Implementing Classes:

PriorityVector, SkewHeap, VectorHeap

public interface PriorityQueue<E extends java.lang.Comparable<E>>

Interface describing an queue of prioritized values. This linear-like structure has values that are inserted in such a way as to allow them to be removed in increasing order.

Example usage:

To print out a list of programmers sorted by age we could use the following:

 public static void main(String[] argv){
      //initialize a new fib heap
      PriorityQueue programmers = new FibHeap();

      //add programmers and their ages to heap
      //ages current of 7/22/2002
        programmers.add(new ComparableAssociation(new Integer(22), "Evan"));
      programmers.add(new ComparableAssociation(new Integer(19), "Chris"));
      programmers.add(new ComparableAssociation(new Integer(20), "Shimon"));
      programmers.add(new ComparableAssociation(new Integer(21), "Diane"));
      programmers.add(new ComparableAssociation(new Integer(21), "Lida"));    
      programmers.add(new ComparableAssociation(new Integer(20), "Rob"));     
      programmers.add(new ComparableAssociation(new Integer(20), "Sean"));    

      //print out programmers 
      while(!programmers.isEmpty()){
          ComparableAssociation p = (ComparableAssociation)programmers.remove();
          System.out.println(p.getValue() + " is " + p.getKey() + " years old.");
      }
 }
 

Method Summary

void	add(E value) Add a value to the priority queue.
void	clear() Remove all the elements from the queue.
E	getFirst() Fetch lowest valued (highest priority) item from queue.
boolean	isEmpty() Determine if the queue is empty.
E	remove() Returns the minimum value from the queue.
int	size() Determine the size of the queue.

Method Detail

getFirst

E getFirst()

Fetch lowest valued (highest priority) item from queue.

Returns:

The smallest value from queue.

Precondition:

!isEmpty()

Postcondition:

returns the minimum value in priority queue

remove

E remove()

Returns the minimum value from the queue.

Returns:

The minimum value in the queue.

Precondition:

!isEmpty()

Postcondition:

returns and removes minimum value from queue

add

void add(E value)

Add a value to the priority queue.

Parameters:

value - The value to be added.

Precondition:

value is non-null comparable

Postcondition:

value is added to priority queue

isEmpty

boolean isEmpty()

Determine if the queue is empty.

Returns:

True if the queue is empty.

Postcondition:

returns true iff no elements are in queue

size

int size()

Determine the size of the queue.

Returns:

The number of elements within the queue.

Postcondition:

returns number of elements within queue

clear

void clear()

Remove all the elements from the queue.

Postcondition:

removes all elements from queue