JRadioButton


1   /*
2    * @(#)JRadioButton.java    1.74 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package javax.swing;
8   
9   import java.awt.*;
10  import java.awt.event.*;
11  import java.beans.*;
12  
13  import javax.swing.plaf.*;
14  import javax.accessibility.*;
15  
16  import java.io.ObjectOutputStream  ;
17  import java.io.ObjectInputStream  ;
18  import java.io.IOException  ;
19  
20  
21  /**
22   * An implementation of a radio button -- an item that can be selected or
23   * deselected, and which displays its state to the user.
24   * Used with a {@link ButtonGroup} object to create a group of buttons
25   * in which only one button at a time can be selected. (Create a ButtonGroup
26   * object and use its <code>add</code> method to include the JRadioButton objects
27   * in the group.)
28   * <blockquote>
29   * <strong>Note:</strong>
30   * The ButtonGroup object is a logical grouping -- not a physical grouping.
31   * Tocreate a button panel, you should still create a {@link JPanel} or similar
32   * container-object and add a {@link javax.swing.border.Border} to it to set it off from surrounding
33   * components.
34   * </blockquote>
35   * <p>
36   * See <a HREF="http://java.sun.com/docs/books/tutorial/uiswing/components/button.html">How to Use Buttons, Check Boxes, and Radio Buttons</a>
37   * in <em>The Java Tutorial</em>
38   * for further documentation.
39   * <p>
40   * <strong>Warning:</strong>
41   * Serialized objects of this class will not be compatible with
42   * future Swing releases. The current serialization support is
43   * appropriate for short term storage or RMI between applications running
44   * the same version of Swing.  As of 1.4, support for long term storage
45   * of all JavaBeans<sup><font size="-2">TM</font></sup>
46   * has been added to the <code>java.beans</code> package.
47   * Please see {@link java.beans.XMLEncoder}.
48   * 
49   * @beaninfo
50   *   attribute: isContainer false
51   * description: A component which can display it's state as selected or deselected.
52   *
53   * @see ButtonGroup
54   * @see JCheckBox
55   * @version 1.74 12/19/03
56   * @author Jeff Dinkins
57   */
58  public class JRadioButton extends JToggleButton   implements Accessible {
59  
60      /**
61       * @see #getUIClassID
62       * @see #readObject
63       */
64      private static final String   uiClassID = "RadioButtonUI";
65  
66  
67      /**
68       * Creates an initially unselected radio button
69       * with no set text.
70       */
71      public JRadioButton () {
72          this(null, null, false);
73      }
74       
75      /**
76       * Creates an initially unselected radio button
77       * with the specified image but no text.
78       *
79       * @param icon  the image that the button should display
80       */
81      public JRadioButton(Icon   icon) {
82          this(null, icon, false);
83      }
84  
85      /**
86       * Creates a radiobutton where properties are taken from the 
87       * Action supplied.
88       *
89       * @since 1.3
90       */
91      public JRadioButton(Action   a) {
92          this();
93      setAction(a);
94      }
95  
96      /**
97       * Creates a radio button with the specified image
98       * and selection state, but no text.
99       *   
100      * @param icon  the image that the button should display
101      * @param selected  if true, the button is initially selected;
102      *                  otherwise, the button is initially unselected
103      */
104     public JRadioButton(Icon   icon, boolean selected) {
105         this(null, icon, selected);
106     }
107     
108     /**
109      * Creates an unselected radio button with the specified text.
110      * 
111      * @param text  the string displayed on the radio button
112      */
113     public JRadioButton (String   text) {
114         this(text, null, false);
115     }
116 
117     /**
118      * Creates a radio button with the specified text
119      * and selection state.
120      * 
121      * @param text  the string displayed on the radio button
122      * @param selected  if true, the button is initially selected;
123      *                  otherwise, the button is initially unselected
124      */
125     public JRadioButton (String   text, boolean selected) {
126         this(text, null, selected);
127     }
128 
129     /**
130      * Creates a radio button that has the specified text and image,
131      * and that is initially unselected.
132      *
133      * @param text  the string displayed on the radio button 
134      * @param icon  the image that the button should display
135      */
136     public JRadioButton(String   text, Icon   icon) {
137         this(text, icon, false);
138     }
139 
140     /**
141      * Creates a radio button that has the specified text, image,
142      * and selection state.
143      *
144      * @param text  the string displayed on the radio button 
145      * @param icon  the image that the button should display
146      */
147     public JRadioButton (String   text, Icon   icon, boolean selected) {
148         super(text, icon, selected);
149         setBorderPainted(false);
150         setHorizontalAlignment(LEADING);
151     }
152 
153 
154     /**
155      * Resets the UI property to a value from the current look and feel.
156      *
157      * @see JComponent#updateUI
158      */
159     public void updateUI() {
160         setUI((ButtonUI)UIManager.getUI(this));
161     }
162     
163 
164     /**
165      * Returns the name of the L&F class
166      * that renders this component.
167      *
168      * @return String "RadioButtonUI"
169      * @see JComponent#getUIClassID
170      * @see UIDefaults#getUI
171      * @beaninfo
172      *        expert: true
173      *   description: A string that specifies the name of the L&F class.
174      */
175     public String   getUIClassID() {
176         return uiClassID;
177     }
178 
179 
180     /**
181      * Factory method which sets the <code>ActionEvent</code> source's
182      * properties according to values from the Action instance. The
183      * properties which are set may differ for subclasses.
184      * By default, the properties which get set are <code>Text, Mnemonic,
185      * Enabled, ActionCommand</code>, and <code>ToolTipText</code>.
186      *
187      * @param a the Action from which to get the properties, or null
188      * @since 1.3
189      * @see Action
190      * @see #setAction
191      */
192     protected void configurePropertiesFromAction(Action   a) {
193         String  [] types = { Action.MNEMONIC_KEY, Action.NAME,
194                            Action.SHORT_DESCRIPTION,
195                            Action.ACTION_COMMAND_KEY, "enabled" };
196         configurePropertiesFromAction(a, types);
197     }
198 
199     /**
200      * Factory method which creates the PropertyChangeListener
201      * used to update the ActionEvent source as properties change on
202      * its Action instance.  Subclasses may override this in order 
203      * to provide their own PropertyChangeListener if the set of
204      * properties which should be kept up to date differs from the
205      * default properties (Text, Icon, Enabled, ToolTipText).
206      *
207      * Note that PropertyChangeListeners should avoid holding
208      * strong references to the ActionEvent source, as this may hinder
209      * garbage collection of the ActionEvent source and all components
210      * in its containment hierarchy.  
211      *
212      * @since 1.3
213      * @see Action
214      * @see #setAction
215      */
216     protected PropertyChangeListener createActionPropertyChangeListener(Action   a) {
217         return new AbstractActionPropertyChangeListener  (this, a) {
218         public void propertyChange(PropertyChangeEvent e) {     
219         String   propertyName = e.getPropertyName();
220         AbstractButton   button = (AbstractButton  )getTarget();
221         if (button == null) {   //WeakRef GC'ed in 1.2
222             Action   action = (Action  )e.getSource();
223             action.removePropertyChangeListener(this);
224         } else {
225             if (propertyName.equals(Action.NAME)) {
226             String   text = (String  ) e.getNewValue();
227             button.setText(text);
228             button.repaint();
229             } else if (propertyName.equals(Action.SHORT_DESCRIPTION)) {
230             String   text = (String  ) e.getNewValue();
231             button.setToolTipText(text);
232             } else if (propertyName.equals("enabled")) {
233             Boolean   enabledState = (Boolean  ) e.getNewValue();
234             button.setEnabled(enabledState.booleanValue());
235             button.repaint();
236                     } else if (propertyName.equals(Action.ACTION_COMMAND_KEY)) {
237                         button.setActionCommand((String  )e.getNewValue());
238             } 
239         }
240         }
241     };
242     }
243 
244     /** 
245      * See readObject() and writeObject() in JComponent for more 
246      * information about serialization in Swing.
247      */
248     private void writeObject(ObjectOutputStream   s) throws IOException   {
249         s.defaultWriteObject();
250         if (getUIClassID().equals(uiClassID)) {
251             byte count = JComponent.getWriteObjCounter(this);
252             JComponent.setWriteObjCounter(this, --count);
253             if (count == 0 && ui != null) {
254                 ui.installUI(this);
255             }
256         }
257     }
258 
259 
260     /**
261      * Returns a string representation of this JRadioButton. This method 
262      * is intended to be used only for debugging purposes, and the 
263      * content and format of the returned string may vary between      
264      * implementations. The returned string may be empty but may not 
265      * be <code>null</code>.
266      * 
267      * @return  a string representation of this JRadioButton.
268      */
269     protected String   paramString() {
270     return super.paramString();
271     }
272 
273 
274 /////////////////
275 // Accessibility support
276 ////////////////
277 
278 
279     /**
280      * Gets the AccessibleContext associated with this JRadioButton. 
281      * For JRadioButtons, the AccessibleContext takes the form of an 
282      * AccessibleJRadioButton. 
283      * A new AccessibleJRadioButton instance is created if necessary.
284      *
285      * @return an AccessibleJRadioButton that serves as the 
286      *         AccessibleContext of this JRadioButton
287      * @beaninfo
288      *       expert: true
289      *  description: The AccessibleContext associated with this Button
290      */
291     public AccessibleContext getAccessibleContext() {
292         if (accessibleContext == null) {
293             accessibleContext = new AccessibleJRadioButton();
294         }
295         return accessibleContext;
296     }
297 
298     /**
299      * This class implements accessibility support for the 
300      * <code>JRadioButton</code> class.  It provides an implementation of the 
301      * Java Accessibility API appropriate to radio button 
302      * user-interface elements.
303      * <p>
304      * <strong>Warning:</strong>
305      * Serialized objects of this class will not be compatible with
306      * future Swing releases. The current serialization support is
307      * appropriate for short term storage or RMI between applications running
308      * the same version of Swing.  As of 1.4, support for long term storage
309      * of all JavaBeans<sup><font size="-2">TM</font></sup>
310      * has been added to the <code>java.beans</code> package.
311      * Please see {@link java.beans.XMLEncoder}.
312      */
313     protected class AccessibleJRadioButton extends AccessibleJToggleButton {
314 
315         /**
316          * Get the role of this object.
317          *
318          * @return an instance of AccessibleRole describing the role of the object
319          * @see AccessibleRole
320          */
321         public AccessibleRole getAccessibleRole() {
322             return AccessibleRole.RADIO_BUTTON;
323         }
324 
325     } // inner class AccessibleJRadioButton
326 }
327   
328
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