001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2007, 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 2000-2007, 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 * Changes (from 21-Aug-2001)
037 * --------------------------
038 * 21-Aug-2001 : Added standard header. Fixed DOS encoding problem (DG);
039 * 18-Sep-2001 : Updated e-mail address in header (DG);
040 * 15-Oct-2001 : Moved to new package (com.jrefinery.data.*) (DG);
041 * 22-Oct-2001 : Renamed DataSource.java --> Dataset.java etc. (DG);
042 * 17-Nov-2001 : Changed constructor from public to protected, created new
043 * AbstractSeriesDataset class and transferred series-related
044 * methods, updated Javadoc comments (DG);
045 * 04-Mar-2002 : Updated import statements (DG);
046 * 11-Jun-2002 : Updated for change in the event constructor (DG);
047 * 07-Aug-2002 : Changed listener list to use
048 * javax.swing.event.EventListenerList (DG);
049 * 04-Oct-2002 : Fixed errors reported by Checkstyle (DG);
050 * 27-Mar-2003 : Implemented Serializable (DG);
051 * 18-Aug-2003 : Implemented Cloneable (DG);
052 * 08-Sep-2003 : Serialization fixes (NB);
053 * 11-Sep-2003 : Cloning Fixes (NB);
054 * 01-Jun-2005 : Added hasListener() method for unit testing (DG);
055 *
056 */
057
058 package org.jfree.data.general;
059
060 import java.io.IOException;
061 import java.io.InvalidObjectException;
062 import java.io.ObjectInputStream;
063 import java.io.ObjectInputValidation;
064 import java.io.ObjectOutputStream;
065 import java.io.Serializable;
066 import java.util.Arrays;
067 import java.util.EventListener;
068 import java.util.List;
069
070 import javax.swing.event.EventListenerList;
071
072 /**
073 * An abstract implementation of the {@link Dataset} interface, containing a
074 * mechanism for registering change listeners.
075 */
076 public abstract class AbstractDataset implements Dataset,
077 Cloneable,
078 Serializable,
079 ObjectInputValidation {
080
081 /** For serialization. */
082 private static final long serialVersionUID = 1918768939869230744L;
083
084 /** The group that the dataset belongs to. */
085 private DatasetGroup group;
086
087 /** Storage for registered change listeners. */
088 private transient EventListenerList listenerList;
089
090 /**
091 * Constructs a dataset. By default, the dataset is assigned to its own
092 * group.
093 */
094 protected AbstractDataset() {
095 this.group = new DatasetGroup();
096 this.listenerList = new EventListenerList();
097 }
098
099 /**
100 * Returns the dataset group for the dataset.
101 *
102 * @return The group.
103 */
104 public DatasetGroup getGroup() {
105 return this.group;
106 }
107
108 /**
109 * Sets the dataset group for the dataset.
110 *
111 * @param group the group (<code>null</code> not permitted).
112 */
113 public void setGroup(DatasetGroup group) {
114 if (group == null) {
115 throw new IllegalArgumentException("Null 'group' argument.");
116 }
117 this.group = group;
118 }
119
120 /**
121 * Registers an object to receive notification of changes to the dataset.
122 *
123 * @param listener the object to register.
124 */
125 public void addChangeListener(DatasetChangeListener listener) {
126 this.listenerList.add(DatasetChangeListener.class, listener);
127 }
128
129 /**
130 * Deregisters an object so that it no longer receives notification of
131 * changes to the dataset.
132 *
133 * @param listener the object to deregister.
134 */
135 public void removeChangeListener(DatasetChangeListener listener) {
136 this.listenerList.remove(DatasetChangeListener.class, listener);
137 }
138
139 /**
140 * Returns <code>true</code> if the specified object is registered with
141 * the dataset as a listener. Most applications won't need to call this
142 * method, it exists mainly for use by unit testing code.
143 *
144 * @param listener the listener.
145 *
146 * @return A boolean.
147 */
148 public boolean hasListener(EventListener listener) {
149 List list = Arrays.asList(this.listenerList.getListenerList());
150 return list.contains(listener);
151 }
152
153 /**
154 * Notifies all registered listeners that the dataset has changed.
155 */
156 protected void fireDatasetChanged() {
157 notifyListeners(new DatasetChangeEvent(this, this));
158 }
159
160 /**
161 * Notifies all registered listeners that the dataset has changed.
162 *
163 * @param event contains information about the event that triggered the
164 * notification.
165 */
166 protected void notifyListeners(DatasetChangeEvent event) {
167
168 Object[] listeners = this.listenerList.getListenerList();
169 for (int i = listeners.length - 2; i >= 0; i -= 2) {
170 if (listeners[i] == DatasetChangeListener.class) {
171 ((DatasetChangeListener) listeners[i + 1]).datasetChanged(
172 event
173 );
174 }
175 }
176
177 }
178
179 /**
180 * Returns a clone of the dataset. The cloned dataset will NOT include the
181 * {@link DatasetChangeListener} references that have been registered with
182 * this dataset.
183 *
184 * @return A clone.
185 *
186 * @throws CloneNotSupportedException if the dataset does not support
187 * cloning.
188 */
189 public Object clone() throws CloneNotSupportedException {
190 AbstractDataset clone = (AbstractDataset) super.clone();
191 clone.listenerList = new EventListenerList();
192 return clone;
193 }
194
195 /**
196 * Handles serialization.
197 *
198 * @param stream the output stream.
199 *
200 * @throws IOException if there is an I/O problem.
201 */
202 private void writeObject(ObjectOutputStream stream) throws IOException {
203 stream.defaultWriteObject();
204 }
205
206 /**
207 * Restores a serialized object.
208 *
209 * @param stream the input stream.
210 *
211 * @throws IOException if there is an I/O problem.
212 * @throws ClassNotFoundException if there is a problem loading a class.
213 */
214 private void readObject(ObjectInputStream stream)
215 throws IOException, ClassNotFoundException {
216 stream.defaultReadObject();
217 this.listenerList = new EventListenerList();
218 stream.registerValidation(this, 10); // see comments about priority of
219 // 10 in validateObject()
220 }
221
222 /**
223 * Validates the object. We use this opportunity to call listeners who have
224 * registered during the deserialization process, as listeners are not
225 * serialized. This method is called by the serialization system after the
226 * entire graph is read.
227 *
228 * This object has registered itself to the system with a priority of 10.
229 * Other callbacks may register with a higher priority number to be called
230 * before this object, or with a lower priority number to be called after
231 * the listeners were notified.
232 *
233 * All listeners are supposed to have register by now, either in their
234 * readObject or validateObject methods. Notify them that this dataset has
235 * changed.
236 *
237 * @exception InvalidObjectException If the object cannot validate itself.
238 */
239 public void validateObject() throws InvalidObjectException {
240 fireDatasetChanged();
241 }
242
243 }