Source Code : How to extend the collections framework

Java Is Open Source Programming Language You Can Download From Java and Java Libraries From http://www.oracle.com. Click Here to download
We provide this code related to title for you to solve your developing problem easily. Libraries which is import in this program you can download from http://www.oracle.com. Click Here or search from google with Libraries Name you get jar file related it

How to extend the collections framework

  
/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.util.AbstractQueue;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Queue;

/**
 * This program demonstrates how to extend the collections framework.
 * @version 1.20 2007-05-16
 * @author Cay Horstmann
 */
public class CircularArrayQueueTest
{
   public static void main(String[] args)
   {
      Queue<String> q = new CircularArrayQueue<String>(5);
      q.add("Amy");
      q.add("Bob");
      q.add("Carl");
      q.add("Deedee");
      q.add("Emile");
      q.remove();
      q.add("Fifi");
      q.remove();
      for (String s : q) System.out.println(s);
   }
}

/** 
    A first-in, first-out bounded collection. 
*/ 
class CircularArrayQueue<E> extends AbstractQueue<E>
{ 
   /** 
       Constructs an empty queue. 
       @param capacity the maximum capacity of the queue 
   */ 
   public CircularArrayQueue(int capacity) 
   { 
      elements = new Object[capacity]; 
      count = 0; 
      head = 0; 
      tail = 0; 
   } 

   public boolean offer(E newElement) 
   { 
      assert newElement != null;
      if (count < elements.length) 
      {
         elements[tail] = newElement; 
         tail = (tail + 1) % elements.length; 
         count++;
         modcount++;
         return true;
      }
      else 
         return false;
   } 

   public E poll() 
   { 
      if (count == 0) return null;
      E r = peek(); 
      head = (head + 1) % elements.length; 
      count--; 
      modcount++;
      return r; 
   } 

   @SuppressWarnings("unchecked")
   public E peek() 
   { 
      if (count == 0) return null;
      return (E) elements[head]; 
   } 

   public int size() 
   { 
      return count; 
   } 

   public Iterator<E> iterator()
   {
      return new QueueIterator();
         
   }

   private class QueueIterator implements Iterator<E>
   {
      public QueueIterator()
      {
         modcountAtConstruction = modcount;
      }

      @SuppressWarnings("unchecked")
      public E next() 
      { 
         if (!hasNext()) throw new NoSuchElementException();
         E r = (E) elements[(head + offset) % elements.length]; 
         offset++;
         return r;
      }

      public boolean hasNext() 
      { 
         if (modcount != modcountAtConstruction) 
            throw new ConcurrentModificationException();
         return offset < count;
      }

      public void remove() 
      { 
         throw new UnsupportedOperationException(); 
      }

      private int offset;
      private int modcountAtConstruction;
   }

   private Object[] elements; 
   private int head; 
   private int tail; 
   private int count; 
   private int modcount;
}

   
    
  

Thank with us