001    /* JRadioButton.java -- 
002       Copyright (C) 2002, 2004, 2005  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 javax.swing;
040    
041    import javax.accessibility.AccessibleContext;
042    import javax.accessibility.AccessibleRole;
043    import javax.swing.plaf.ButtonUI;
044    
045    /**
046     * The <code>JRadioButton</code> component provides a visually selectable
047     * button with mutually exclusive behaviour within a <code>ButtonGroup</code>.
048     * A series of radio buttons can be used to provide options to the user,
049     * where the user can only select one of the available options.  The state
050     * of the button is provided by the superclass, <code>JToggleButton</code>.
051     * <code>JRadioButton</code> adds the additional behaviour, that if two
052     * or more radio buttons are grouped together, the selection of one implies
053     * the deselection of the other buttons within the group.
054     * <p>
055     *
056     * Buttons are grouped by adding each instance to a <code>ButtonGroup</code>.
057     * The existence of such a grouping is not reflected visually, so other means
058     * should be used to denote this.  For instance, the grouped buttons can be placed
059     * within the same panel, possibly with an appropriate border to denote
060     * the connection between the components.
061     *
062     * @author Michael Koch  (konqueror@gmx.de)
063     * @author Graydon Hoare  (graydon@redhat.com)
064     * @author Andrew John Hughes  (gnu_andrew@member.fsf.org)
065     * @see JToggleButton
066     * @see ButtonGroup
067     * @since 1.2
068     */
069    public class JRadioButton extends JToggleButton
070    {
071      /**
072       * Compatible with Sun's JDK.
073       */
074      private static final long serialVersionUID = 7751949583255506856L;
075    
076      /**
077       * This class provides accessibility support for the toggle button.
078       */
079      protected class AccessibleJRadioButton
080        extends AccessibleJToggleButton
081      {
082        private static final long serialVersionUID = 4850967637026120674L;
083    
084        /**
085         * Constructor for the accessible toggle button.
086         */
087        protected AccessibleJRadioButton()
088        {
089            /* Call the superclass to register for events */
090            super();
091        }
092    
093        /**
094         * Returns the accessible role for the toggle button.
095         *
096         * @return An instance of <code>AccessibleRole</code>, describing
097         *         the role of the toggle button.
098         */
099        public AccessibleRole getAccessibleRole()
100        {
101          return AccessibleRole.RADIO_BUTTON;
102        }
103    
104      }
105    
106      /**
107       * Constructs an unselected radio button with no text or icon.
108       */ 
109      public JRadioButton()
110      {
111        this(null, null, false);
112      }
113        
114      /**
115       * Constructs a radio button using the labelling, state
116       * and icon specified by the supplied action.
117       *
118       * @param a the action to use to define the properties of the button.
119       */
120      public JRadioButton(Action a)
121      {
122        this();
123        setAction(a);
124      }
125    
126      /**
127       * Constructs an unselected radio button with the supplied icon
128       * and no text.
129       *
130       * @param icon the icon to use.
131       */
132      public JRadioButton(Icon icon)
133      { 
134        this(null, icon, false);
135      }    
136      
137      /**
138       * Constructs a radio button with the supplied icon and state.
139       *
140       * @param icon the icon to use.
141       * @param selected if true, the radio button is initially in the
142       *        selected state.  Otherwise, the button is unselected.
143       */
144      public JRadioButton(Icon icon, boolean selected)
145      { 
146        this(null, icon, selected);
147      }    
148      
149      /**
150       * Constructs an unselected radio button using the supplied text
151       * and no icon.
152       *
153       * @param text the text to use.
154       */
155      public JRadioButton(String text)
156      {
157        this(text, null, false);
158      }
159    
160      /**
161       * Constructs a radio button with the supplied text and state.
162       *
163       * @param text the text to use.
164       * @param selected if true, the radio button is initially in the
165       *        selected state.  Otherwise, the button is unselected.
166       */
167      public JRadioButton(String text, boolean selected)
168      {
169        this(text, null, selected);
170      }
171          
172      /**
173       * Constructs an unselected radio button with the supplied text
174       * and icon.
175       *
176       * @param text the text to use.
177       * @param icon the icon to use.
178       */
179      public JRadioButton(String text, Icon icon)
180      {
181        this(text, icon, false);
182      }
183      
184      /**
185       * Constructs a radio button with the supplied text, icon and state.
186       *
187       * @param text the text to use.
188       * @param icon the icon to use.
189       * @param selected if true, the radio button is initially in the
190       *        selected state.  Otherwise, the button is unselected.
191       */
192      public JRadioButton(String text, Icon icon, boolean selected)
193      {
194        super(text, icon, selected);
195        setBorderPainted(false);
196        setHorizontalAlignment(LEADING);
197      }
198          
199      /**
200       * Returns the accessible context for this <code>JRadioButton</code>,
201       * in the form of an instance of <code>AccessibleJRadioButton</code>.
202       * The context is created, if necessary.
203       *
204       * @return the associated context
205       */
206      public AccessibleContext getAccessibleContext()
207      {
208        /* Create the context if this is the first request */
209        if (accessibleContext == null)
210          {
211            /* Create the context */
212            accessibleContext = new AccessibleJRadioButton();
213          }
214        return accessibleContext;
215      }
216      
217      /**
218       * Returns a string specifying the name of the Look and Feel UI class
219       * that renders this component.
220       *
221       * @return the Look and Feel UI class for <code>JRadioButton</code>s
222       *         as a <code>String</code>.
223       */  
224      public String getUIClassID()
225      {
226        return "RadioButtonUI";
227      }
228      
229      /**
230       * Returns a string representation of this component for debugging use.
231       * Users should not depend on anything as regards the content or formatting
232       * of this string, except for the fact that the returned string may never be
233       * null (only empty).
234       *
235       * @return the component in <code>String</code> form for debugging.
236       */  
237      protected  String paramString()
238      {
239        return super.paramString();
240      }
241      
242      /**
243       * This method resets the radio button's UI delegate to the default UI for
244       * the current look and feel.
245       */
246      public void updateUI()
247      {
248        /* 
249           I can't see any difference between this and the superclass one,
250           but Sun reimplements it... there is no RadioButtonUI class for it
251           to be cast to.
252        */
253        setUI((ButtonUI) UIManager.getUI(this));
254      }
255    
256    }
257    
258    
259