001 /* java.beans.PropertyEditorSupport
002 Copyright (C) 1998, 2004 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.beans;
040
041
042 /**
043 * PropertyEditorSupport helps with PropertyEditors,
044 * implementing base functionality that they usually must
045 * have but which is a pain to implement. You may extend
046 * from this class or use it as a standalone.<P>
047 *
048 * This class does not do any painting or actual editing.
049 * For that, you must use or extend it. See the
050 * PropertyEditor class for better descriptions of what
051 * the various methods do.
052 *
053 * @author John Keiser
054 * @author Robert Schuster
055 * @since 1.1
056 * @status updated to 1.5
057 */
058 public class PropertyEditorSupport implements PropertyEditor
059 {
060 Object eventSource;
061 Object value;
062 PropertyChangeSupport pSupport;
063
064 /** Call this constructor when you are deriving from
065 * PropertyEditorSupport.
066 *
067 * Using this constructor the event source is this PropertyEditorSupport
068 * instance itself.
069 *
070 * @since 1.5
071 * @specnote this was <code>protected</code> prior to 1.5
072 */
073 public PropertyEditorSupport()
074 {
075 eventSource = this;
076 pSupport = new PropertyChangeSupport(this);
077 }
078
079 /** Call this constructor when you are using
080 * PropertyEditorSupport as a helper object.
081 *
082 * This constructor throws a NullPointerException when <code>source</code> is <code>null</code>,
083 * for compatibility reasons with J2SDK 1.5.0 .
084 *
085 * @param source The source to use when firing
086 * property change events.
087 * @since 1.5
088 * @specnote this was <code>protected</code> prior to 1.5
089 */
090 public PropertyEditorSupport(Object source)
091 {
092 // note: constructor rejects source being null for the sake of compatibility
093 // with official 1.5.0 implementation
094 if (source == null)
095 throw new NullPointerException("Event source must not be null.");
096
097 eventSource = source;
098 pSupport = new PropertyChangeSupport(eventSource);
099 }
100
101 /** Sets the current value of the property and a property change
102 * event is fired to all registered PropertyChangeListener instances.
103 *
104 * @param newValue The new value for the property.
105 */
106 public void setValue(Object newValue)
107 {
108 value = newValue;
109
110 // specification in java.beans.PropertyChangeEvent says
111 // that without a property name (first argument) the
112 // new and the old value should always be null
113 pSupport.firePropertyChange(null, null, null);
114 }
115
116 /** Gets the current value of the property.
117 *
118 * @return the current value of the property.
119 */
120 public Object getValue()
121 {
122 return value;
123 }
124
125 /** Gets whether this object is paintable or not.
126 *
127 * @return <CODE>false</CODE>
128 */
129 public boolean isPaintable()
130 {
131 return false;
132 }
133
134 /** Paints this object. This class does nothing in
135 * this method.
136 */
137 public void paintValue(java.awt.Graphics g, java.awt.Rectangle r)
138 {
139 }
140
141 /** Gets the Java initialization String for the current
142 * value of the Object. This class returns gibberish or
143 * null (though the spec does not say which).<P>
144 * <STRONG>Implementation Note:</STRONG> This class
145 * returns the string "@$#^" to make sure the code will
146 * be broken, so that you will know to override it when
147 * you create your own property editor.
148 *
149 * @return the Java initialization string.
150 */
151 public String getJavaInitializationString()
152 {
153 return "@$#^";
154 }
155
156 /** Gets the value as text.
157 * In this class, you cannot count on getAsText() doing
158 * anything useful, although in this implementation I
159 * do toString().
160 *
161 * @return the value as text.
162 */
163 public String getAsText()
164 {
165 return value != null ? value.toString() : "null";
166 }
167
168 /** Sets the value as text.
169 * In this class, you cannot count on setAsText() doing
170 * anything useful across implementations.
171 * <STRONG>Implementation Note:</STRONG> In this
172 * implementation it checks if the String is "null", and
173 * if it is, sets the value to null, otherwise it throws
174 * an IllegalArgumentException.
175 *
176 * @param s the text to convert to a new value.
177 * @exception IllegalArgumentException if the text is
178 * malformed.
179 */
180 public void setAsText(String s) throws IllegalArgumentException
181 {
182 if (s.equals("null"))
183 setValue(null);
184 else
185 throw new IllegalArgumentException();
186 }
187
188 /** Returns a list of possible choices for the value.
189 *
190 * @return <CODE>null</CODE>
191 */
192 public String[] getTags()
193 {
194 return null;
195 }
196
197 /** Returns a custom component to edit the value.
198 *
199 * @return <CODE>null</CODE> in this class.
200 */
201 public java.awt.Component getCustomEditor()
202 {
203 return null;
204 }
205
206 /** Finds out whether this property editor supports a
207 * custom component to edit its value.
208 *
209 * @return <CODE>false</CODE> in this class.
210 */
211 public boolean supportsCustomEditor()
212 {
213 return false;
214 }
215
216 /** Adds a property change listener to this property editor.
217 *
218 * @param l the listener to add.
219 */
220 public void addPropertyChangeListener(PropertyChangeListener l)
221 {
222 pSupport.addPropertyChangeListener(l);
223 }
224
225 /** Removes a property change listener from this property editor.
226 *
227 * @param l the listener to remove.
228 */
229 public void removePropertyChangeListener(PropertyChangeListener l)
230 {
231 pSupport.removePropertyChangeListener(l);
232 }
233
234 /** Notifies people that we've changed, although we don't
235 * tell them just how.
236 */
237 public void firePropertyChange()
238 {
239 pSupport.firePropertyChange(null, null, null);
240 }
241
242 /** Returns the bean that is used as the source of events.
243 *
244 * @return The event source object
245 * @since 1.5
246 */
247 public Object getSource()
248 {
249 return eventSource;
250 }
251
252 /** Sets the bean that is used as the source of events
253 * when property changes occur.
254 *
255 * The event source bean is for informational purposes only
256 * and should not be changed by the <code>PropertyEditor</code>.
257 *
258 * @param source
259 * @since 1.5
260 */
261 public void setSource(Object source)
262 {
263 eventSource = source;
264 }
265 }