old-autovect-branch/libjava/classpath/javax/swing/ButtonGroup.java

   1 /* ButtonGroup.java --
   2    Copyright (C) 2002 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., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 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 package javax.swing;
  39
  40 import java.io.Serializable;
  41 import java.util.Enumeration;
  42 import java.util.Vector;
  43
  44
  45 /**
  46  * Logically groups a set of buttons, so that only one of the buttons in
  47  * a <code>ButtonGroup</code> can be selected at the same time. If one
  48  * button in a <code>ButtonGroup</code> is selected, all other buttons
  49  * are automatically deselected.
  50  *
  51  * While <code>ButtonGroup</code> can be used for all buttons that are derived
  52  * from {@link AbstractButton}, it is normally only used for
  53  * {@link JRadioButton}s, {@link JRadioButtonMenuItem}s and
  54  * {@link JToggleButton}s.
  55  *
  56  * You could use it for {@link JCheckBox}es, but for the sake of usability
  57  * this is strongly discouraged because the common expectation of checkboxes
  58  * is that the user is allowed to make multiple selections.
  59  *
  60  * It makes no sense to put {@link JButton}s or {@link JMenuItem}s in
  61  * a <code>ButtonGroup</code> because they don't implement the
  62  * <code>selected</code> semantics.
  63  *
  64  * @author original author unknown
  65  */
  66 public class ButtonGroup implements Serializable
  67 {
  68   /** DOCUMENT ME! */
  69   private static final long serialVersionUID = 4259076101881721375L;
  70
  71   /** The buttons added to this button group. */
  72   protected Vector buttons = new Vector();
  73
  74   /** The currently selected button model. */
  75   ButtonModel sel;
  76
  77   /**
  78    * Creates a new button group.
  79    */
  80   public ButtonGroup()
  81   {
  82     // Nothing to do here.
  83   }
  84
  85   /**
  86    * Adds a button to this group.
  87    *
  88    * @param b the button to add
  89    */
  90   public void add(AbstractButton b)
  91   {
  92     b.getModel().setGroup(this);
  93     if (b.isSelected())
  94       sel = b.getModel();
  95     buttons.addElement(b);
  96   }
  97
  98   /**
  99    * Removed a given button from this group.
 100    *
 101    * @param b the button to remove
 102    */
 103   public void remove(AbstractButton b)
 104   {
 105     b.getModel().setGroup(null);
 106     buttons.removeElement(b);
 107   }
 108
 109   /**
 110    * Returns the currently added buttons.
 111    *
 112    * @return <code>Enumeration</code> over all added buttons
 113    */
 114   public Enumeration getElements()
 115   {
 116     return buttons.elements();
 117   }
 118
 119   /**
 120    * Returns the currently selected button model.
 121    *
 122    * @return the currently selected button model, null if none was selected
 123    *         yet
 124    */
 125   public ButtonModel getSelection()
 126   {
 127     return sel;
 128   }
 129
 130   /**
 131    * DOCUMENT ME!
 132    *
 133    * @param m DOCUMENT ME!
 134    *
 135    * @return DOCUMENT ME!
 136    */
 137   AbstractButton FindButton(ButtonModel m)
 138   {
 139     for (int i = 0; i < buttons.size(); i++)
 140       {
 141         AbstractButton a = (AbstractButton) buttons.get(i);
 142         if (a.getModel() == m)
 143           return a;
 144       }
 145     return null;
 146   }
 147
 148   /**
 149    * Sets the currently selected button model. Only one button of a group can
 150    * be selected at a time.
 151    *
 152    * @param m the model to select
 153    * @param b true if this button is to be selected, false otherwise
 154    */
 155   public void setSelected(ButtonModel m, boolean b)
 156   {
 157     if ((sel != m || b) && (! b || sel == m))
 158       return;
 159
 160     if (b && sel != m)
 161       {
 162         ButtonModel old = sel;
 163         sel = m;
 164
 165         if (old != null)
 166           old.setSelected(false);
 167         AbstractButton button = FindButton(old);
 168         if (button != null)
 169           button.repaint();
 170       }
 171     else if (!b && sel == m)
 172       m.setSelected(true);
 173   }
 174
 175   /**
 176    * Checks if the given <code>ButtonModel</code> is selected in this button
 177    * group.
 178    *
 179    * @param m DOCUMENT ME!
 180    *
 181    * @return true of given <code>ButtonModel</code> is selected, false
 182    *         otherwise
 183    */
 184   public boolean isSelected(ButtonModel m)
 185   {
 186     return m == sel;
 187   }
 188
 189   /**
 190    * Return the number of buttons in this button group.
 191    *
 192    * @return the number of buttons
 193    *
 194    * @since 1.3
 195    */
 196   public int getButtonCount()
 197   {
 198     return buttons.size();
 199   }
 200 }