libjava/java/beans/PropertyEditorSupport.java

   1 /* java.beans.PropertyEditorSupport
   2    Copyright (C) 1998 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.beans;
  40
  41 /**
  42  ** PropertyEditorSupport helps with PropertyEditors,
  43  ** implementing base functionality that they usually must
  44  ** have but which is a pain to implement.  You may extend
  45  ** from this class or use it as a standalone.<P>
  46  **
  47  ** This class does not do any painting or actual editing.
  48  ** For that, you must use or extend it.  See the
  49  ** PropertyEditor class for better descriptions of what
  50  ** the various methods do.
  51  **
  52  ** @author John Keiser
  53  ** @since JDK1.1
  54  ** @version 1.1.0, 29 Jul 1998
  55  **/
  56
  57 public class PropertyEditorSupport implements PropertyEditor {
  58         Object eventSource;
  59         Object val;
  60         PropertyChangeSupport pSupport;
  61
  62         /** Call this constructor when you are deriving from
  63          ** PropertyEditorSupport.
  64          **/
  65         protected PropertyEditorSupport() {
  66                 this.eventSource = this;
  67                 this.pSupport = new PropertyChangeSupport(this);
  68         }
  69
  70         /** Call this constructor when you are using
  71          ** PropertyEditorSupport as a helper object.
  72          ** @param eventSource the source to use when firing
  73          **        property change events.
  74          **/
  75         protected PropertyEditorSupport(Object eventSource) {
  76                 this.eventSource = eventSource;
  77                 this.pSupport = new PropertyChangeSupport(this);
  78         }
  79
  80         /** Set the current value of the property.
  81          ** <STRONG>Implementation Note</STRONG> Sun does not
  82          ** state what exactly this version of the method does.
  83          ** Thus, in this implementation, it sets the value, and
  84          ** then if the old and new values are different, it
  85          ** fires a property change event with no property name
  86          ** and the old and new values.
  87          ** @param val the new value for the property.
  88          **/
  89         public void setValue(Object val) {
  90                 Object oldVal = val;
  91                 this.val = val;
  92                 if(!oldVal.equals(val)) {
  93                         pSupport.firePropertyChange(null,oldVal,val);
  94                 }
  95         }
  96
  97         /** Get the current value of the property.
  98          ** @return the current value of the property.
  99          **/
 100         public Object getValue() {
 101                 return val;
 102         }
 103
 104         /** Get whether this object is paintable or not.
 105          ** @return <CODE>false</CODE>
 106          **/
 107         public boolean isPaintable() {
 108                 return false;
 109         }
 110
 111         /** Paint this object.  This class does nothing in
 112          ** this method.
 113          **/
 114         public void paintValue(java.awt.Graphics g, java.awt.Rectangle r) {
 115         }
 116
 117         /** Get the Java initialization String for the current
 118          ** value of the Object.  This class returns gibberish or
 119          ** null (though the spec does not say which).<P>
 120          ** <STRONG>Implementation Note:</STRONG> This class
 121          ** returns the string "@$#^" to make sure the code will
 122          ** be broken, so that you will know to override it when
 123          ** you create your own property editor.
 124          ** @return the Java initialization string.
 125          **/
 126         public String getJavaInitializationString() {
 127                 return "@$#^";
 128         }
 129
 130         /** Get the value as text.
 131          ** In this class, you cannot count on getAsText() doing
 132          ** anything useful, although in this implementation I
 133          ** do toString().
 134          ** @return the value as text.
 135          **/
 136         public String getAsText() {
 137                 return val != null ? val.toString() : "null";
 138         }
 139
 140         /** Set the value as text.
 141          ** In this class, you cannot count on setAsText() doing
 142          ** anything useful across implementations.
 143          ** <STRONG>Implementation Note:</STRONG> In this
 144          ** implementation it checks if the String is "null", and
 145          ** if it is, sets the value to null, otherwise it throws
 146          ** an IllegalArgumentException.
 147          ** @param s the text to convert to a new value.
 148          ** @exception IllegalArgumentException if the text is
 149          **            malformed.
 150          **/
 151         public void setAsText(String s) throws IllegalArgumentException {
 152                 if(s.equals("null")) {
 153                         setValue(null);
 154                 } else {
 155                         throw new IllegalArgumentException();
 156                 }
 157         }
 158
 159         /** Returns a list of possible choices for the value.
 160          ** @return <CODE>null</CODE>
 161          **/
 162         public String[] getTags() {
 163                 return null;
 164         }
 165
 166         /** Return a custom component to edit the value.
 167          ** @return <CODE>null</CODE> in this class.
 168          **/
 169         public java.awt.Component getCustomEditor() {
 170                 return null;
 171         }
 172
 173         /** Find out whether this property editor supports a
 174          ** custom component to edit its value.
 175          ** @return <CODE>false</CODE> in this class.
 176          **/
 177         public boolean supportsCustomEditor() {
 178                 return false;
 179         }
 180
 181         /** Add a property change listener to this property editor.
 182          ** @param l the listener to add.
 183          **/
 184         public void addPropertyChangeListener(PropertyChangeListener l) {
 185                 pSupport.addPropertyChangeListener(l);
 186         }
 187
 188         /** Remove a property change listener from this property editor.
 189          ** @param l the listener to remove.
 190          **/
 191         public void removePropertyChangeListener(PropertyChangeListener l) {
 192                 pSupport.removePropertyChangeListener(l);
 193         }
 194
 195
 196         /** Notify people that we've changed, although we don't
 197          ** tell them just how.  The only thing I can think of to
 198          ** send in the event is the new value (since the old value
 199          ** is unavailable and there is no property name).
 200          ** I confess I do not understand the point of this method.
 201          **/
 202         public void firePropertyChange() {
 203                 pSupport.firePropertyChange(null,null,val);
 204         }
 205 }
 206