2 * Copyright (c) 2002-2007 Sun Microsystems, Inc. All rights reserved.
4 * The Sun Project JXTA(TM) Software License
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
16 * 3. The end-user documentation included with the redistribution, if any, must
17 * include the following acknowledgment: "This product includes software
18 * developed by Sun Microsystems, Inc. for JXTA(TM) technology."
19 * Alternately, this acknowledgment may appear in the software itself, if
20 * and wherever such third-party acknowledgments normally appear.
22 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
23 * not be used to endorse or promote products derived from this software
24 * without prior written permission. For written permission, please contact
25 * Project JXTA at http://www.jxta.org.
27 * 5. Products derived from this software may not be called "JXTA", nor may
28 * "JXTA" appear in their name, without prior written permission of Sun.
30 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
32 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SUN
33 * MICROSYSTEMS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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39 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 * JXTA is a registered trademark of Sun Microsystems, Inc. in the United
42 * States and other countries.
44 * Please see the license information page at :
45 * <http://www.jxta.org/project/www/license.html> for instructions on use of
46 * the license in source files.
48 * ====================================================================
50 * This software consists of voluntary contributions made by many individuals
51 * on behalf of Project JXTA. For more information on Project JXTA, please see
52 * http://www.jxta.org.
54 * This license is based on the BSD license adopted by the Apache Foundation.
57 package net.jxta.impl.util;
61 * A cheap doubly linked list.
62 * It is far less general than java's LinkedList but permits much better
63 * removal performance from the middle of the list because a contained
64 * element and the corresponding chaining object are one and the same.
66 * The major inconvenient of Dlink is that it is a class, not an
67 * interface. Making it an interface does not make sense since one would have
68 * to re-implement it entirely. A DList is just a stand-alone
69 * Dlink with just a couple of additional convenience methods.
71 * Note this class does not keep an element count. The way element removal
72 * works makes it impossible. Do it from the outside.
75 public class Dlist extends Dlink {
77 public void putLast(Dlink ne) {
81 public void putFirst(Dlink ne) {
89 public Dlink first() {
93 public void addLast(Dlink ne) {
97 public void addFirst(Dlink ne) {
101 public Dlink getLast() {
105 public Dlink getFirst() {
109 public Dlink removeLast() {
116 public Dlink removeFirst() {
123 public void clear() {
127 public boolean isEmpty() {