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    }