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Java > Open Source Codes > org > jfree > xml > writer > AttributeList


1 /* ========================================================================
2  * JCommon : a free general purpose class library for the Java(tm) platform
3  * ========================================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jcommon/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ------------------
28  * AttributeList.java
29  * ------------------
30  * (C)opyright 2003-2005, by Thomas Morgner and Contributors.
31  *
32  * Original Author: Thomas Morgner;
33  * Contributor(s): David Gilbert (for Object Refinery Limited);
34  *
35  * $Id: AttributeList.java,v 1.3 2005/10/18 13:35:06 mungady Exp $
36  *
37  * Changes
38  * -------
39  * 25-Sep-2003 : Initial version (TM);
40  * 26-Nov-2003 : Javadoc updates (DG);
41  *
42  */
43
44 package org.jfree.xml.writer;
45
46 import java.util.Iterator JavaDoc;
47 import java.util.List JavaDoc;
48
49 /**
50  * The attribute list is used by a writer to specify the attributes
51  * of an XML element in a certain order.
52  *
53  * @author Thomas Morgner
54  */
55 public class AttributeList {
56
57     /**
58      * A name/value pair of the attribute list.
59      */
60     private static class AttributeEntry {
61         
62         /** The name of the attribute entry. */
63         private String JavaDoc name;
64         
65         /** The value of the attribute entry. */
66         private String JavaDoc value;
67
68         /**
69          * Creates a new attribute entry for the given name and value.
70          *
71          * @param name the attribute name (<code>null</code> not permitted).
72          * @param value the attribute value (<code>null</code> not permitted).
73          */
74         public AttributeEntry(final String JavaDoc name, final String JavaDoc value) {
75             if (name == null) {
76                 throw new NullPointerException JavaDoc("Name must not be null. ["
77                                                + name + ", " + value + "]");
78             }
79             if (value == null) {
80                 throw new NullPointerException JavaDoc("Value must not be null. ["
81                                                + name + ", " + value + "]");
82             }
83             this.name = name;
84             this.value = value;
85         }
86
87         /**
88          * Returns the attribute name.
89          *
90          * @return the name.
91          */
92         public String JavaDoc getName() {
93             return this.name;
94         }
95
96         /**
97          * Returns the value of this attribute entry.
98          *
99          * @return the value of the entry.
100          */
101         public String JavaDoc getValue() {
102             return this.value;
103         }
104
105         /**
106          * Checks whether the given object is an attribute entry with the same name.
107          *
108          * @param o the suspected other attribute entry.
109          *
110          * @return <code>true</code> if the given object is equal, <code>false</code> otherwise.
111          */
112         public boolean equals(final Object JavaDoc o) {
113             if (this == o) {
114                 return true;
115             }
116             if (!(o instanceof AttributeEntry)) {
117                 return false;
118             }
119
120             final AttributeEntry attributeEntry = (AttributeEntry) o;
121             if (!this.name.equals(attributeEntry.name)) {
122                 return false;
123             }
124             return true;
125         }
126
127         /**
128          * Computes an hashcode for this entry.
129          *
130          * @return the hashcode.
131          */
132         public int hashCode() {
133             return this.name.hashCode();
134         }
135     }
136
137     /**
138      * An iterator over the attribute names of this list.
139      */
140     private static class AttributeIterator implements Iterator JavaDoc {
141         
142         /** The backend is an iterator over the attribute entries. */
143         private Iterator JavaDoc backend;
144
145         /**
146          * Creates a new attribute iterator using the given iterator as backend.
147          *
148          * @param backend an iterator over the attribute entries (<code>null</code> not permitted).
149          */
150         public AttributeIterator(final Iterator JavaDoc backend) {
151             if (backend == null) {
152                 throw new NullPointerException JavaDoc();
153             }
154             this.backend = backend;
155         }
156
157         /**
158          * Returns <tt>true</tt> if the iteration has more elements. (In other
159          * words, returns <tt>true</tt> if <tt>next</tt> would return an element
160          * rather than throwing an exception.)
161          *
162          * @return <tt>true</tt> if the iterator has more elements.
163          */
164         public boolean hasNext() {
165             return this.backend.hasNext();
166         }
167
168         /**
169          * Returns the next element in the iteration.
170          *
171          * @return the next element in the iteration.
172          */
173         public Object JavaDoc next() {
174             final AttributeEntry entry = (AttributeEntry) this.backend.next();
175             if (entry != null) {
176                 return entry.getName();
177             }
178             return entry;
179         }
180
181         /**
182          *
183          * Removes from the underlying collection the last element returned by the
184          * iterator (optional operation). This method can be called only once per
185          * call to <tt>next</tt>. The behavior of an iterator is unspecified if
186          * the underlying collection is modified while the iteration is in
187          * progress in any way other than by calling this method.
188          */
189         public void remove() {
190             this.backend.remove();
191         }
192     }
193
194     /** The storage for all entries of this list. */
195     private List JavaDoc entryList;
196
197     /**
198      * Creates an empty attribute list with no default values.
199      */
200     public AttributeList() {
201         this.entryList = new java.util.ArrayList JavaDoc();
202     }
203
204     /**
205      * Returns an iterator over all attribute names. The names are returned
206      * in their oder of addition to the list. The iterator contains strings.
207      *
208      * @return the iterator over all attribute names.
209      */
210     public Iterator JavaDoc keys() {
211         return new AttributeIterator(this.entryList.iterator());
212     }
213
214     /**
215      * Defines an attribute.
216      *
217      * @param name the name of the attribute to be defined
218      * @param value the value of the attribute.
219      */
220     public synchronized void setAttribute(final String JavaDoc name, final String JavaDoc value) {
221         final AttributeEntry entry = new AttributeEntry(name, value);
222         final int pos = this.entryList.indexOf(entry);
223         if (pos != -1) {
224             this.entryList.remove(pos);
225         }
226         this.entryList.add(entry);
227     }
228
229     /**
230      * Returns the attribute value for the given attribute name or null,
231      * if the attribute is not defined in this list.
232      *
233      * @param name the name of the attribute
234      * @return the attribute value or null.
235      */
236     public synchronized String JavaDoc getAttribute(final String JavaDoc name) {
237         return getAttribute(name, null);
238     }
239
240     /**
241      * Returns the attribute value for the given attribute name or the given
242      * defaultvalue, if the attribute is not defined in this list.
243      *
244      * @param name the name of the attribute.
245      * @param defaultValue the default value.
246      *
247      * @return the attribute value or the defaultValue.
248      */
249     public synchronized String JavaDoc getAttribute(final String JavaDoc name, final String JavaDoc defaultValue) {
250         for (int i = 0; i < this.entryList.size(); i++) {
251             final AttributeEntry ae = (AttributeEntry) this.entryList.get(i);
252             if (ae.getName().equals(name)) {
253                 return ae.getValue();
254             }
255         }
256         return defaultValue;
257     }
258
259     /**
260      * Removes the attribute with the given name from the list.
261      *
262      * @param name the name of the attribute which should be removed..
263      */
264     public synchronized void removeAttribute(final String JavaDoc name) {
265         for (int i = 0; i < this.entryList.size(); i++) {
266             final AttributeEntry ae = (AttributeEntry) this.entryList.get(i);
267             if (ae.getName().equals(name)) {
268                 this.entryList.remove(ae);
269                 return;
270             }
271         }
272     }
273 }
274
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