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Java > Open Source Codes > org > jdom > contrib > helpers > JDOMHelper


1 /*--
2
3  $Id: JDOMHelper.java,v 1.4 2004/02/06 09:57:48 jhunter Exp $
4
5  Copyright (C) 2000-2004 Jason Hunter & Brett McLaughlin.
6  All rights reserved.
7
8  Redistribution and use in source and binary forms, with or without
9  modification, are permitted provided that the following conditions
10  are met:
11
12  1. Redistributions of source code must retain the above copyright
13     notice, this list of conditions, and the following disclaimer.
14
15  2. Redistributions in binary form must reproduce the above copyright
16     notice, this list of conditions, and the disclaimer that follows
17     these conditions in the documentation and/or other materials
18     provided with the distribution.
19
20  3. The name "JDOM" must not be used to endorse or promote products
21     derived from this software without prior written permission. For
22     written permission, please contact <request_AT_jdom_DOT_org>.
23
24  4. Products derived from this software may not be called "JDOM", nor
25     may "JDOM" appear in their name, without prior written permission
26     from the JDOM Project Management <request_AT_jdom_DOT_org>.
27
28  In addition, we request (but do not require) that you include in the
29  end-user documentation provided with the redistribution and/or in the
30  software itself an acknowledgement equivalent to the following:
31      "This product includes software developed by the
32       JDOM Project (http://www.jdom.org/)."
33  Alternatively, the acknowledgment may be graphical using the logos
34  available at http://www.jdom.org/images/logos.
35
36  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
37  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
38  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
39  DISCLAIMED. IN NO EVENT SHALL THE JDOM AUTHORS OR THE PROJECT
40  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
42  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
43  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
44  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
45  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
46  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
47  SUCH DAMAGE.
48
49  This software consists of voluntary contributions made by many
50  individuals on behalf of the JDOM Project and was originally
51  created by Jason Hunter <jhunter_AT_jdom_DOT_org> and
52  Brett McLaughlin <brett_AT_jdom_DOT_org>. For more information
53  on the JDOM Project, please see <http://www.jdom.org/>.
54
55  */
56
57 package org.jdom.contrib.helpers;
58
59 import org.jdom.*;
60 import java.util.*;
61
62 /** <p>
63  * This class contains static helper methods.
64  * </p>
65  * @author Alex Rosen
66  */
67 public class JDOMHelper {
68     /**
69      * <p>
70      * Sorts the child elements, using the specified comparator.
71      * @param parent The parent Element, whose child Elements should be sorted.
72      * @param c The Comparator to use for ordering the child Elements.
73      * It will only be given Element objects to compare.
74      * </p>
75      * <p>
76      * This method overcomes two problems with the standard Collections.sort():
77      * <ul>
78      * <li>Collections.sort() doesn't bother to remove an item from its old
79      * location before placing it in its new location, which causes JDOM to
80      * complain that the item has been added twice.
81      * <li>This method will sort the child Elements without moving any other
82      * content, such as formatting text nodes (newlines, indents, etc.)
83      * Otherwise, all the formatting whitespace would move to the beginning
84      * or end of the content list.
85      * (Note that this means that the elements will now be in a different
86      * order with respect to any comments, which may cause a problem
87      * if the comments describe the elements.)
88      * </ul>
89      * </p>
90      */
91     public static void sortElements(Element parent, Comparator c) {
92         // Create a new, static list of child elements, and sort it.
93 List children = new ArrayList(parent.getChildren());
94         Collections.sort(children, c);
95         ListIterator childrenIter = children.listIterator();
96         
97         // Create a new, static list of all content items.
98 List content = new ArrayList(parent.getContent());
99         ListIterator contentIter = content.listIterator();
100
101         // Loop through the content items, and whenever we find an Element,
102 // we'll insert the next ordered Element in its place. Because the
103 // content list is not live, it won't complain about an Element being
104 // added twice.
105 while(contentIter.hasNext()) {
106             Object JavaDoc obj = contentIter.next();
107             if (obj instanceof Element)
108                 contentIter.set(childrenIter.next());
109         }
110
111         // Finally, we set the content list back into the parent Element.
112 parent.setContent((List)null);
113         parent.setContent(content);
114     }
115 }
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