1  import java.util.LinkedList;

  2  import java.util.PriorityQueue;

  3  import java.util.Queue;

  4  import java.util.Stack;

  5  

  6  /**

  7     This program demonstrates stacks, queues, and priority queues.

  8  */

  9  public class StackQueueDemo

 10  {

 11     public static void main(String[] args)

 12     {

 13        System.out.println("Stack: ");

 14        Stack<String> s = new Stack<String>();

 15        s.push("Tom");

 16        s.push("Diana");

 17        s.push("Harry");

 18        while (s.size() > 0) { System.out.println(s.pop()); }

 19  

 20        System.out.println("Queue: ");

 21        Queue<String> q = new LinkedList<String>();

 22        q.add("Tom");

 23        q.add("Diana");

 24        q.add("Harry");

 25        while (q.size() > 0) { System.out.println(q.remove()); }

 26  

 27        System.out.println("Priority Queue: ");

 28        PriorityQueue<String> pq = new PriorityQueue<String>();

 29        pq.add("Tom");

 30        pq.add("Diana");

 31        pq.add("Harry");

 32        while (pq.size() > 0) { System.out.println(pq.remove()); }

 33     }

 34  }