Source for javax.swing.ButtonGroup

   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:   }
  83: 
  84:   /**
  85:    * Adds a button to this group.
  86:    *
  87:    * @param b the button to add
  88:    */
  89:   public void add(AbstractButton b)
  90:   {
  91:     b.getModel().setGroup(this);
  92:     buttons.addElement(b);
  93:   }
  94: 
  95:   /**
  96:    * Removed a given button from this group.
  97:    *
  98:    * @param b the button to remove
  99:    */
 100:   public void remove(AbstractButton b)
 101:   {
 102:     b.getModel().setGroup(null);
 103:     buttons.removeElement(b);
 104:   }
 105: 
 106:   /**
 107:    * Returns the currently added buttons.
 108:    *
 109:    * @return <code>Enumeration</code> over all added buttons
 110:    */
 111:   public Enumeration getElements()
 112:   {
 113:     return buttons.elements();
 114:   }
 115: 
 116:   /**
 117:    * Returns the currently selected button model.
 118:    *
 119:    * @return the currently selected button model, null if none was selected
 120:    *         yet
 121:    */
 122:   public ButtonModel getSelection()
 123:   {
 124:     return sel;
 125:   }
 126: 
 127:   /**
 128:    * DOCUMENT ME!
 129:    *
 130:    * @param m DOCUMENT ME!
 131:    *
 132:    * @return DOCUMENT ME!
 133:    */
 134:   AbstractButton FindButton(ButtonModel m)
 135:   {
 136:     for (int i = 0; i < buttons.size(); i++)
 137:       {
 138:     AbstractButton a = (AbstractButton) buttons.get(i);
 139:     if (a.getModel() == m)
 140:       return a;
 141:       }
 142:     return null;
 143:   }
 144: 
 145:   /**
 146:    * Sets the currently selected button model. Only one button of a group can
 147:    * be selected at a time.
 148:    *
 149:    * @param m the model to select
 150:    * @param b true if this button is to be selected, false otherwise
 151:    */
 152:   public void setSelected(ButtonModel m, boolean b)
 153:   {
 154:     if ((sel != m || b) && (! b || sel == m))
 155:       return;
 156: 
 157:     if (b && sel != m)
 158:       {
 159:         ButtonModel old = sel;
 160:         sel = m;
 161: 
 162:         if (old != null)
 163:           old.setSelected(false);
 164:         AbstractButton button = FindButton(old);
 165:         if (button != null)
 166:           button.repaint();
 167:       }
 168:     else if (!b && sel == m)
 169:       m.setSelected(true);
 170:   }
 171: 
 172:   /**
 173:    * Checks if the given <code>ButtonModel</code> is selected in this button
 174:    * group.
 175:    *
 176:    * @param m DOCUMENT ME!
 177:    *
 178:    * @return true of given <code>ButtonModel</code> is selected, false
 179:    *         otherwise
 180:    */
 181:   public boolean isSelected(ButtonModel m)
 182:   {
 183:     return m == sel;
 184:   }
 185: 
 186:   /**
 187:    * Return the number of buttons in this button group.
 188:    *
 189:    * @return the number of buttons
 190:    *
 191:    * @since 1.3
 192:    */
 193:   public int getButtonCount()
 194:   {
 195:     return buttons.size();
 196:   }
 197: }