001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, 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 2000-2008, 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, Cloneable,
077 Serializable, ObjectInputValidation {
078
079 /** For serialization. */
080 private static final long serialVersionUID = 1918768939869230744L;
081
082 /** The group that the dataset belongs to. */
083 private DatasetGroup group;
084
085 /** Storage for registered change listeners. */
086 private transient EventListenerList listenerList;
087
088 /**
089 * Constructs a dataset. By default, the dataset is assigned to its own
090 * group.
091 */
092 protected AbstractDataset() {
093 this.group = new DatasetGroup();
094 this.listenerList = new EventListenerList();
095 }
096
097 /**
098 * Returns the dataset group for the dataset.
099 *
100 * @return The group (never <code>null</code>).
101 *
102 * @see #setGroup(DatasetGroup)
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 * @see #getGroup()
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 * @see #removeChangeListener(DatasetChangeListener)
128 */
129 public void addChangeListener(DatasetChangeListener listener) {
130 this.listenerList.add(DatasetChangeListener.class, listener);
131 }
132
133 /**
134 * Deregisters an object so that it no longer receives notification of
135 * changes to the dataset.
136 *
137 * @param listener the object to deregister.
138 *
139 * @see #addChangeListener(DatasetChangeListener)
140 */
141 public void removeChangeListener(DatasetChangeListener listener) {
142 this.listenerList.remove(DatasetChangeListener.class, listener);
143 }
144
145 /**
146 * Returns <code>true</code> if the specified object is registered with
147 * the dataset as a listener. Most applications won't need to call this
148 * method, it exists mainly for use by unit testing code.
149 *
150 * @param listener the listener.
151 *
152 * @return A boolean.
153 *
154 * @see #addChangeListener(DatasetChangeListener)
155 * @see #removeChangeListener(DatasetChangeListener)
156 */
157 public boolean hasListener(EventListener listener) {
158 List list = Arrays.asList(this.listenerList.getListenerList());
159 return list.contains(listener);
160 }
161
162 /**
163 * Notifies all registered listeners that the dataset has changed.
164 *
165 * @see #addChangeListener(DatasetChangeListener)
166 */
167 protected void fireDatasetChanged() {
168 notifyListeners(new DatasetChangeEvent(this, this));
169 }
170
171 /**
172 * Notifies all registered listeners that the dataset has changed.
173 *
174 * @param event contains information about the event that triggered the
175 * notification.
176 *
177 * @see #addChangeListener(DatasetChangeListener)
178 * @see #removeChangeListener(DatasetChangeListener)
179 */
180 protected void notifyListeners(DatasetChangeEvent event) {
181
182 Object[] listeners = this.listenerList.getListenerList();
183 for (int i = listeners.length - 2; i >= 0; i -= 2) {
184 if (listeners[i] == DatasetChangeListener.class) {
185 ((DatasetChangeListener) listeners[i + 1]).datasetChanged(
186 event);
187 }
188 }
189
190 }
191
192 /**
193 * Returns a clone of the dataset. The cloned dataset will NOT include the
194 * {@link DatasetChangeListener} references that have been registered with
195 * this dataset.
196 *
197 * @return A clone.
198 *
199 * @throws CloneNotSupportedException if the dataset does not support
200 * cloning.
201 */
202 public Object clone() throws CloneNotSupportedException {
203 AbstractDataset clone = (AbstractDataset) super.clone();
204 clone.listenerList = new EventListenerList();
205 return clone;
206 }
207
208 /**
209 * Handles serialization.
210 *
211 * @param stream the output stream.
212 *
213 * @throws IOException if there is an I/O problem.
214 */
215 private void writeObject(ObjectOutputStream stream) throws IOException {
216 stream.defaultWriteObject();
217 }
218
219 /**
220 * Restores a serialized object.
221 *
222 * @param stream the input stream.
223 *
224 * @throws IOException if there is an I/O problem.
225 * @throws ClassNotFoundException if there is a problem loading a class.
226 */
227 private void readObject(ObjectInputStream stream)
228 throws IOException, ClassNotFoundException {
229 stream.defaultReadObject();
230 this.listenerList = new EventListenerList();
231 stream.registerValidation(this, 10); // see comments about priority of
232 // 10 in validateObject()
233 }
234
235 /**
236 * Validates the object. We use this opportunity to call listeners who have
237 * registered during the deserialization process, as listeners are not
238 * serialized. This method is called by the serialization system after the
239 * entire graph is read.
240 *
241 * This object has registered itself to the system with a priority of 10.
242 * Other callbacks may register with a higher priority number to be called
243 * before this object, or with a lower priority number to be called after
244 * the listeners were notified.
245 *
246 * All listeners are supposed to have register by now, either in their
247 * readObject or validateObject methods. Notify them that this dataset has
248 * changed.
249 *
250 * @exception InvalidObjectException If the object cannot validate itself.
251 */
252 public void validateObject() throws InvalidObjectException {
253 fireDatasetChanged();
254 }
255
256 }