Source code: com/neuron/jaffer/Queue.java

   /* 
    * Copyright (c) 2003 Stewart Allen <stewart@neuron.com>. All rights reserved.
    * This program is free software. See the 'License' file for details.
    */
   
   package com.neuron.jaffer;
   
   import java.io.*;
   import java.net.*;
  import java.util.*;
  
  public class Queue
  {
    private Element head;
    private Element tail;
  
    //private int count;
    //private int maxCount;
  
    private Element createElement(Object obj)
    {
      return new Element(obj);
    }
  
    public void enqueue(Object obj)
    {
      synchronized (this)
      {
        if (tail == null)
        {
          tail = createElement(obj);
          head = tail;
        }
        else
        {
          tail.next = createElement(obj);
          tail = tail.next;
        }
        /*
        count++;
        if (count > maxCount)
        {
          maxCount = count;
          System.out.println("max queue len = "+maxCount+" : "+this);
        }
        */
        this.notify();
      }
    }
  
    public Object dequeue()
    {
      synchronized (this)
      {
        try
        {
          while (head == null)
          {
            this.wait();
          }
        }
        catch (InterruptedException ex)
        {
          return null;
        }
        catch (Exception ex)
        {
          ex.printStackTrace();
          return null;
        }
        Element element = head;
        if (head.next == null)
        {
          head = null;
          tail = null;
        }
        else
        {
          head = head.next;
        }
        //count--;
        return element.object;
      }
    }
  
    private class Element
    {
      Object object;
      Element next;
  
      Element(Object object)
      {
        this.object = object;
      }
    }
  }