Queue.java

//#preprocess
/* *************************************************
 * Copyright (c) 2010 - 2010
 * HT srl,   All rights reserved.
 * Project      : RCS, RCSBlackBerry
 * Package      : blackberry.utils
 * File         : Queue.java
 * Created      : 28-apr-2010
 * *************************************************/
package com.android.dvci.util;

//#ifdef DEBUG
//#endif
//Queue interface
//
// ******************PUBLIC OPERATIONS*********************
// void enqueue( x )      --> Insert x
// Object getFront( )     --> Return least recently inserted item
// Object dequeue( )      --> Return and remove least recent item
// boolean isEmpty( )     --> Return true if empty; else false
// void makeEmpty( )      --> Remove all items
// ******************ERRORS********************************
// getFront or dequeue on empty queue

/**
 * Protocol for queues.
 * 
 * @author Mark Allen Weiss
 */
public interface Queue {

	/**
	 * Return and remove the least recently inserted item from the queue.
	 * 
	 * @return the least recently inserted item in the queue.
	 */
	Object dequeue();

	/**
	 * Insert a new item into the queue.
	 * 
	 * @param x
	 *            the item to insert.
	 */
	void enqueue(Object x);

	/**
	 * Get the least recently inserted item in the queue. Does not alter the
	 * queue.
	 * 
	 * @return the least recently inserted item in the queue.
	 */
	Object getFront();

	/**
	 * Test if the queue is logically empty.
	 * 
	 * @return true if empty, false otherwise.
	 */
	boolean isEmpty();

	/**
	 * Make the queue logically empty.
	 */
	void makeEmpty();
}