Source for javax.swing.DefaultComboBoxModel

   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:           setSelectedItem(getElementAt(selected - 1));
 150:         else 
 151:           setSelectedItem(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:     // No item is selected and object is null, so no change required.
 228:     if (selectedItem == null && object == null)
 229:       return;
 230: 
 231:     // object is already selected so no change required.
 232:     if (selectedItem != null && selectedItem.equals(object))
 233:       return;
 234: 
 235:     // Simply return if object is not in the list.
 236:     if (object != null && getIndexOf(object) == -1)
 237:       return;
 238: 
 239:     // Here we know that object is either an item in the list or null.
 240: 
 241:     // Handle the three change cases: selectedItem is null, object is
 242:     // non-null; selectedItem is non-null, object is null;
 243:     // selectedItem is non-null, object is non-null and they're not
 244:     // equal.
 245:     selectedItem = object;
 246:     fireContentsChanged(this, -1, -1);
 247:   }
 248: 
 249:   /**
 250:    * Returns the selected item.
 251:    *
 252:    * @return The selected item (possibly <code>null</code>).
 253:    */
 254:   public Object getSelectedItem()
 255:   {
 256:     return selectedItem;
 257:   }
 258: 
 259:   /**
 260:    * Returns the element at the specified index in the model's item list.
 261:    *
 262:    * @param index  the element index.
 263:    *
 264:    * @return The element at the specified index in the model's item list, or
 265:    *         <code>null</code> if the <code>index</code> is outside the bounds
 266:    *         of the list.
 267:    */
 268:   public Object getElementAt(int index)
 269:   {
 270:     if (index < 0 || index >= list.size())
 271:       return null;
 272:     return list.elementAt(index);
 273:   }
 274: 
 275:   /**
 276:    * Returns the index of the specified element in the model's item list.
 277:    *
 278:    * @param object  the element.
 279:    *
 280:    * @return The index of the specified element in the model's item list.
 281:    */
 282:   public int getIndexOf(Object object)
 283:   {
 284:     return list.indexOf(object);
 285:   }
 286: }