libjava/classpath/javax/swing/DefaultComboBoxModel.java

   1 /* DefaultComboBoxModel.java --
   2    Copyright (C) 2002, 2004, 2005, 2006, 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.Arrays;
  42 import java.util.Vector;
  43
  44 import javax.swing.event.ListDataEvent;
  45
  46
  47 /**
  48  * A model that stores a list of elements and a selected item (which may be
  49  * <code>null</code>).  Changes to the model are signalled to listeners using
  50  * {@link ListDataEvent}.  This model is designed for use by the
  51  * {@link JComboBox} component.
  52  *
  53  * @author Andrew Selkirk
  54  * @author Olga Rodimina
  55  * @author Robert Schuster
  56  */
  57 public class DefaultComboBoxModel extends AbstractListModel
  58   implements MutableComboBoxModel, Serializable
  59 {
  60   private static final long serialVersionUID = 6698657703676921904L;
  61
  62   /**
  63    * Storage for the elements in the model's list.
  64    */
  65   private Vector list;
  66
  67   /**
  68    * The selected item (<code>null</code> indicates no selection).
  69    */
  70   private Object selectedItem = null;
  71
  72   /**
  73    * Creates a new model, initially empty.
  74    */
  75   public DefaultComboBoxModel()
  76   {
  77     list = new Vector();
  78   }
  79
  80   /**
  81    * Creates a new model and initializes its item list to the values in the
  82    * given array.  The selected item is set to the first item in the array, or
  83    * <code>null</code> if the array length is zero.
  84    *
  85    * @param items  an array containing items for the model (<code>null</code>
  86    *               not permitted).
  87    *
  88    * @throws NullPointerException if <code>items</code> is <code>null</code>.
  89    */
  90   public DefaultComboBoxModel(Object[] items)
  91   {
  92     list = new Vector(Arrays.asList(items));
  93     if (list.size() > 0)
  94       selectedItem = list.get(0);
  95   }
  96
  97   /**
  98    * Creates a new model and initializes its item list to the values in the
  99    * given vector.  The selected item is set to the first item in the vector,
 100    * or <code>null</code> if the vector length is zero.
 101    *
 102    * @param vector  a vector containing items for the model (<code>null</code>
 103    *                not permitted).
 104    *
 105    * @throws NullPointerException if <code>vector</code> is <code>null</code>.
 106    */
 107   public DefaultComboBoxModel(Vector vector)
 108   {
 109     this.list = vector;
 110     if (getSize() > 0)
 111       selectedItem = vector.get(0);
 112   }
 113
 114   /**
 115    * Adds an element to the model's item list and sends a {@link ListDataEvent}
 116    * to all registered listeners.  If the new element is the first item added
 117    * to the list, and the selected item is <code>null</code>, the new element
 118    * is set as the selected item.
 119    *
 120    * @param object item to add to the model's item list.
 121    */
 122   public void addElement(Object object)
 123   {
 124     list.addElement(object);
 125     int index = list.size() - 1;
 126     fireIntervalAdded(this, index, index);
 127     if (list.size() == 1 && selectedItem == null)
 128       setSelectedItem(object);
 129   }
 130
 131   /**
 132    * Removes the element at the specified index from the model's item list
 133    * and sends a {@link ListDataEvent} to all registered listeners.  If the
 134    * element removed was the selected item, then the preceding element becomes
 135    * the new selected item (or the next element, if there is no preceding
 136    * element).
 137    *
 138    * @param index  the index of the item to remove.
 139    *
 140    * @throws ArrayIndexOutOfBoundsException if <code>index</code> is out of
 141    *         bounds.
 142    */
 143   public void removeElementAt(int index)
 144   {
 145     int selected = getIndexOf(selectedItem);
 146     if (selected == index) // choose a new selected item
 147       {
 148         if (selected > 0)
 149           selectedItem = getElementAt(selected - 1);
 150         else
 151           selectedItem = getElementAt(selected + 1);
 152       }
 153     list.removeElementAt(index);
 154     fireIntervalRemoved(this, index, index);
 155   }
 156
 157   /**
 158    * Adds an element at the specified index in the model's item list
 159    * and sends a {@link ListDataEvent} to all registered listeners.
 160    *
 161    * @param object element to insert
 162    * @param index index specifing position in the list where given element
 163    *        should be inserted.
 164    *
 165    * @throws ArrayIndexOutOfBoundsException if <code>index</code> is out of
 166    *         bounds.
 167    *
 168    * @see #addElement(Object)
 169    */
 170   public void insertElementAt(Object object, int index)
 171   {
 172     list.insertElementAt(object, index);
 173     fireIntervalAdded(this, index, index);
 174   }
 175
 176   /**
 177    * Removes an element from the model's item list and sends a
 178    * {@link ListDataEvent} to all registered listeners.  If the item to be
 179    * removed is the current selected item, a new selected item will be set.
 180    * If the element is not found in the model's item list, this method does
 181    * nothing.
 182    *
 183    * @param object  the element to remove.
 184    */
 185   public void removeElement(Object object)
 186   {
 187     int index = getIndexOf(object);
 188     if (index != -1)
 189       removeElementAt(index);
 190   }
 191
 192   /**
 193    * Removes all the items from the model's item list, resets and selected item
 194    * to <code>null</code>, and sends a {@link ListDataEvent} to all registered
 195    * listeners.
 196    */
 197   public void removeAllElements()
 198   {
 199     selectedItem = null;
 200     int size = getSize();
 201     if (size > 0)
 202       {
 203         list.clear();
 204         fireIntervalRemoved(this, 0, size - 1);
 205       }
 206   }
 207
 208   /**
 209    * Returns the number of items in the model's item list.
 210    *
 211    * @return The number of items in the model's item list.
 212    */
 213   public int getSize()
 214   {
 215     return list.size();
 216   }
 217
 218   /**
 219    * Sets the selected item for the model and sends a {@link ListDataEvent} to
 220    * all registered listeners.  The start and end index of the event is set to
 221    * -1 to indicate the model's selection has changed, and not its contents.
 222    *
 223    * @param object  the new selected item (<code>null</code> permitted).
 224    */
 225   public void setSelectedItem(Object object)
 226   {
 227     if (selectedItem == null)
 228       {
 229         if (object == null)
 230           return;
 231       }
 232     else
 233       {
 234         if (selectedItem.equals(object))
 235           return;
 236       }
 237     selectedItem = object;
 238     fireContentsChanged(this, -1, -1);
 239   }
 240
 241   /**
 242    * Returns the selected item.
 243    *
 244    * @return The selected item (possibly <code>null</code>).
 245    */
 246   public Object getSelectedItem()
 247   {
 248     return selectedItem;
 249   }
 250
 251   /**
 252    * Returns the element at the specified index in the model's item list.
 253    *
 254    * @param index  the element index.
 255    *
 256    * @return The element at the specified index in the model's item list, or
 257    *         <code>null</code> if the <code>index</code> is outside the bounds
 258    *         of the list.
 259    */
 260   public Object getElementAt(int index)
 261   {
 262     if (index < 0 || index >= list.size())
 263       return null;
 264     return list.elementAt(index);
 265   }
 266
 267   /**
 268    * Returns the index of the specified element in the model's item list.
 269    *
 270    * @param object  the element.
 271    *
 272    * @return The index of the specified element in the model's item list.
 273    */
 274   public int getIndexOf(Object object)
 275   {
 276     return list.indexOf(object);
 277   }
 278 }