001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2006, by Object Refinery Limited and Contributors.
006 *
007 * Project Info: http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
022 * USA.
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
025 * in the United States and other countries.]
026 *
027 * --------------------
028 * AbstractDataset.java
029 * --------------------
030 * (C)opyright 2000-2006, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): Nicolas Brodu (for Astrium and EADS Corporate Research
034 * Center);
035 *
036 * $Id: AbstractDataset.java,v 1.5.2.2 2006/07/26 12:14:20 mungady Exp $
037 *
038 * Changes (from 21-Aug-2001)
039 * --------------------------
040 * 21-Aug-2001 : Added standard header. Fixed DOS encoding problem (DG);
041 * 18-Sep-2001 : Updated e-mail address in header (DG);
042 * 15-Oct-2001 : Moved to new package (com.jrefinery.data.*) (DG);
043 * 22-Oct-2001 : Renamed DataSource.java --> Dataset.java etc. (DG);
044 * 17-Nov-2001 : Changed constructor from public to protected, created new
045 * AbstractSeriesDataset class and transferred series-related
046 * methods, updated Javadoc comments (DG);
047 * 04-Mar-2002 : Updated import statements (DG);
048 * 11-Jun-2002 : Updated for change in the event constructor (DG);
049 * 07-Aug-2002 : Changed listener list to use
050 * javax.swing.event.EventListenerList (DG);
051 * 04-Oct-2002 : Fixed errors reported by Checkstyle (DG);
052 * 27-Mar-2003 : Implemented Serializable (DG);
053 * 18-Aug-2003 : Implemented Cloneable (DG);
054 * 08-Sep-2003 : Serialization fixes (NB);
055 * 11-Sep-2003 : Cloning Fixes (NB);
056 * 01-Jun-2005 : Added hasListener() method for unit testing (DG);
057 *
058 */
059
060 package org.jfree.data.general;
061
062 import java.io.IOException;
063 import java.io.InvalidObjectException;
064 import java.io.ObjectInputStream;
065 import java.io.ObjectInputValidation;
066 import java.io.ObjectOutputStream;
067 import java.io.Serializable;
068 import java.util.Arrays;
069 import java.util.EventListener;
070 import java.util.List;
071
072 import javax.swing.event.EventListenerList;
073
074 /**
075 * An abstract implementation of the {@link Dataset} interface, containing a
076 * mechanism for registering change listeners.
077 */
078 public abstract class AbstractDataset implements Dataset,
079 Cloneable,
080 Serializable,
081 ObjectInputValidation {
082
083 /** For serialization. */
084 private static final long serialVersionUID = 1918768939869230744L;
085
086 /** The group that the dataset belongs to. */
087 private DatasetGroup group;
088
089 /** Storage for registered change listeners. */
090 private transient EventListenerList listenerList;
091
092 /**
093 * Constructs a dataset. By default, the dataset is assigned to its own
094 * group.
095 */
096 protected AbstractDataset() {
097 this.group = new DatasetGroup();
098 this.listenerList = new EventListenerList();
099 }
100
101 /**
102 * Returns the dataset group for the dataset.
103 *
104 * @return The group.
105 */
106 public DatasetGroup getGroup() {
107 return this.group;
108 }
109
110 /**
111 * Sets the dataset group for the dataset.
112 *
113 * @param group the group (<code>null</code> not permitted).
114 */
115 public void setGroup(DatasetGroup group) {
116 if (group == null) {
117 throw new IllegalArgumentException("Null 'group' argument.");
118 }
119 this.group = group;
120 }
121
122 /**
123 * Registers an object to receive notification of changes to the dataset.
124 *
125 * @param listener the object to register.
126 */
127 public void addChangeListener(DatasetChangeListener listener) {
128 this.listenerList.add(DatasetChangeListener.class, listener);
129 }
130
131 /**
132 * Deregisters an object so that it no longer receives notification of
133 * changes to the dataset.
134 *
135 * @param listener the object to deregister.
136 */
137 public void removeChangeListener(DatasetChangeListener listener) {
138 this.listenerList.remove(DatasetChangeListener.class, listener);
139 }
140
141 /**
142 * Returns <code>true</code> if the specified object is registered with
143 * the dataset as a listener. Most applications won't need to call this
144 * method, it exists mainly for use by unit testing code.
145 *
146 * @param listener the listener.
147 *
148 * @return A boolean.
149 */
150 public boolean hasListener(EventListener listener) {
151 List list = Arrays.asList(this.listenerList.getListenerList());
152 return list.contains(listener);
153 }
154
155 /**
156 * Notifies all registered listeners that the dataset has changed.
157 */
158 protected void fireDatasetChanged() {
159 notifyListeners(new DatasetChangeEvent(this, this));
160 }
161
162 /**
163 * Notifies all registered listeners that the dataset has changed.
164 *
165 * @param event contains information about the event that triggered the
166 * notification.
167 */
168 protected void notifyListeners(DatasetChangeEvent event) {
169
170 Object[] listeners = this.listenerList.getListenerList();
171 for (int i = listeners.length - 2; i >= 0; i -= 2) {
172 if (listeners[i] == DatasetChangeListener.class) {
173 ((DatasetChangeListener) listeners[i + 1]).datasetChanged(
174 event
175 );
176 }
177 }
178
179 }
180
181 /**
182 * Returns a clone of the dataset. The cloned dataset will NOT include the
183 * {@link DatasetChangeListener} references that have been registered with
184 * this dataset.
185 *
186 * @return A clone.
187 *
188 * @throws CloneNotSupportedException if the dataset does not support
189 * cloning.
190 */
191 public Object clone() throws CloneNotSupportedException {
192 AbstractDataset clone = (AbstractDataset) super.clone();
193 clone.listenerList = new EventListenerList();
194 return clone;
195 }
196
197 /**
198 * Handles serialization.
199 *
200 * @param stream the output stream.
201 *
202 * @throws IOException if there is an I/O problem.
203 */
204 private void writeObject(ObjectOutputStream stream) throws IOException {
205 stream.defaultWriteObject();
206 }
207
208 /**
209 * Restores a serialized object.
210 *
211 * @param stream the input stream.
212 *
213 * @throws IOException if there is an I/O problem.
214 * @throws ClassNotFoundException if there is a problem loading a class.
215 */
216 private void readObject(ObjectInputStream stream)
217 throws IOException, ClassNotFoundException {
218 stream.defaultReadObject();
219 this.listenerList = new EventListenerList();
220 stream.registerValidation(this, 10); // see comments about priority of
221 // 10 in validateObject()
222 }
223
224 /**
225 * Validates the object. We use this opportunity to call listeners who have
226 * registered during the deserialization process, as listeners are not
227 * serialized. This method is called by the serialization system after the
228 * entire graph is read.
229 *
230 * This object has registered itself to the system with a priority of 10.
231 * Other callbacks may register with a higher priority number to be called
232 * before this object, or with a lower priority number to be called after
233 * the listeners were notified.
234 *
235 * All listeners are supposed to have register by now, either in their
236 * readObject or validateObject methods. Notify them that this dataset has
237 * changed.
238 *
239 * @exception InvalidObjectException If the object cannot validate itself.
240 */
241 public void validateObject() throws InvalidObjectException {
242 fireDatasetChanged();
243 }
244
245 }