PriorityQueue Examples

PriorityQueue 1 - Construction, enumeration, pushing, popping.
PriorityQueue1 Example Code// Copyright(c) 1996 ObjectSpace, Inc.

import java.util.Enumeration;
import jgl.*;

/**
 * Construction, enumeration, pushing, popping. 
 * 
 * @see jgl.PriorityQueue
 * @version 1.1
 * @author ObjectSpace, Inc.
 */

public class PriorityQueue1
  {
  public static void main( String[] args )
    {
    // Use a HashComparator for comparing elements. Since the hash value of an 
    // Integer is its int value, this will order Integers in descending order.
    PriorityQueue queue = new PriorityQueue(); 
    queue.push( new Integer( 5 ) );
    queue.push( new Integer( -2 ) );
    queue.push( new Integer( 10 ) );
    queue.push( new Integer( 6 ) );
    queue.push( new Integer( 20 ) );
    queue.push( new Integer( -10 ) );

    // Note that although a PriorityQueue always pops objects in the order determined
    // by the comparator, this *does not* mean that the objects are stored in order
    // within the internal data structure. The internal data structure is organized as 
    // a heap.
    System.out.println( "Print the PriorityQueue." );
    System.out.println( queue );
    System.out.println();

    System.out.println( "Non-destructively enumerate the PriorityQueue." );
    Enumeration e = queue.elements();
    while( e.hasMoreElements() )
      System.out.println( e.nextElement() );
    System.out.println();

    System.out.println( "Pop and print each element." );
    while( !queue.isEmpty() )
      System.out.println( queue.pop() );
    }
  }

PriorityQueue1 Example Output
Print the PriorityQueue.
PriorityQueue( Array( 20, 10, 5, -2, 6, -10 ) )

Non-destructively enumerate the PriorityQueue.
20
10
5
-2
6
-10

Pop and print each element.
20
10
6
5
-2
-10