Source for javax.swing.SpinnerListModel

   1: /* SpinnerListModel.java -- A spinner model backed by a list or an array.
   2:    Copyright (C) 2004, 2005  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.ArrayList;
  42: import java.util.Arrays;
  43: import java.util.List;
  44: 
  45: import javax.swing.event.ChangeEvent;
  46: 
  47: /**
  48:  * An implementation of <code>SpinnerModel</code> which uses the values
  49:  * contained within a list or an array.  The backing list or array is
  50:  * only stored as a reference within the class.  As a result, changes
  51:  * made elsewhere to the members of the list or array are reflected by
  52:  * this model.
  53:  * <p>
  54:  *
  55:  * The model itself inherits a list of <code>ChangeListener</code>s from
  56:  * <code>AbstractSpinnerModel</code>.  As this code is unaware of changes
  57:  * made to the backing list or array, it is the responsibility of the
  58:  * application using the model to invoke <code>fireStateChanged()</code>,
  59:  * in order to notify any <code>ChangeListener</code>s, when the list or array
  60:  * changes.  The model handles notification when the reference itself
  61:  * is changed via <code>setList()</code> or when the current value is
  62:  * set directly using <code>setValue()</code>.
  63:  *
  64:  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  65:  * @see SpinnerModel
  66:  * @see AbstractSpinnerModel
  67:  * @see JSpinner
  68:  * @since 1.4
  69:  */
  70: 
  71: public class SpinnerListModel extends AbstractSpinnerModel
  72:   implements Serializable
  73: {
  74:   /**
  75:    * For compatability with Sun's JDK
  76:    */
  77:   private static final long serialVersionUID = 3358804052191994516L;
  78: 
  79:   /**
  80:    * The backing list for this model.
  81:    */
  82:   private List list;
  83: 
  84:   /**
  85:    * The current index in the list.
  86:    */
  87:   private transient int index;
  88: 
  89:   /**
  90:    * Constructs a default <code>SpinnerListModel</code>.  This
  91:    * is a model backed by a list containing only the single
  92:    * <code>String</code> element, "empty".
  93:    */
  94:   public SpinnerListModel()
  95:   {
  96:     List defaultList;
  97: 
  98:     // Create an empty list.
  99:     defaultList = new ArrayList();
 100:     // Add the string "empty".
 101:     defaultList.add("empty");
 102:     // Set the list.
 103:     setList(defaultList);
 104:   }
 105: 
 106:   /**
 107:    * Constructs a <code>SpinnerListModel</code> using the supplied list.
 108:    * The model maintains a reference to this list, and returns
 109:    * consecutive elements in response to calls to <code>getNextValue()</code>.
 110:    * The initial value is that at position 0, so an initial call
 111:    * to <code>getValue()</code> returns the same as <code>list.get(0)</code>.
 112:    *
 113:    * @param list The list to use for this model.
 114:    * 
 115:    * @throws IllegalArgumentException if the list is null or contains no
 116:    *         elements.
 117:    *
 118:    * @see SpinnerListModel#getNextValue()
 119:    * @see SpinnerListModel#getValue()
 120:    */ 
 121:   public SpinnerListModel(List<?> list)
 122:   {
 123:     // Retain a reference to the valid list.
 124:     setList(list);
 125:   }
 126: 
 127:   /**
 128:    * Constructs a <code>SpinnerListModel</code> using the supplied array.
 129:    * The model stores a reference to the wrapper list returned by
 130:    * <code>Arrays.asList()</code>.  The wrapper list reflects modifications
 131:    * in the underlying array, so these changes will also be reflected
 132:    * by the model.  The model produces consecutive elements from the array
 133:    * in response to calls to <code>getNextValue()</code>.  The initial
 134:    * value returned by <code>getValue()</code> is the same as
 135:    * <code>array[0]</code>.
 136:    *
 137:    * @param array The array to use for this model.
 138:    *
 139:    * @throws IllegalArgumentException if the array is null or contains
 140:    *         no elements.
 141:    *
 142:    * @see Arrays#asList(Object[])
 143:    * @see SpinnerListModel#getNextValue()
 144:    * @see SpinnerListModel#getValue()
 145:    */
 146:   public SpinnerListModel(Object[] array)
 147:   {
 148:     // Check for a null or zero-sized array.
 149:     if (array == null || array.length == 0)
 150:       {
 151:         throw new IllegalArgumentException("The supplied array was invalid.");
 152:       }
 153: 
 154:     // Retain a reference to a wrapper around the valid array. 
 155:     // The array, in list form, will be tested again here, but we can't really
 156:     // avoid this -- a null value to Arrays.asList will throw a
 157:     // NullPointerException.
 158:     setList(Arrays.asList(array));
 159:   }
 160: 
 161:   /**
 162:    * Returns the backing list for this model.
 163:    *
 164:    * @return The backing list.
 165:    */
 166:   public List<?> getList()
 167:   {
 168:     return list;
 169:   }
 170:     
 171:   /**
 172:    * Returns the next value from the list, which is the same as the element
 173:    * stored at the current index + 1.  Null is returned if there are no more
 174:    * values to be returned (the end of the list has been reached).  An
 175:    * ambiguity can occur here, as null may also be returned as a valid list
 176:    * element.  This operation does not change the current value.
 177:    *
 178:    * @return The next value from the list or null.
 179:    */
 180:   public Object getNextValue()
 181:   {
 182:     // Check for a next value.
 183:     if (index < (list.size() - 1))
 184:       // Return the element at the next index.
 185:       return list.get(index + 1);
 186:     else
 187:       // Return null as this is the end of the list.
 188:       return null;
 189:     }
 190: 
 191:   /**
 192:    * Returns the previous value from the list, which is the same as the element
 193:    * stored at the current index - 1.  Null is returned if there are no more
 194:    * values to be returned (the start of the list has been reached).  An
 195:    * ambiguity can occur here, as null may also be returned as a valid list
 196:    * element.  This operation does not change the current value.
 197:    *
 198:    * @return The previous value from the list or null.
 199:    */
 200:   public Object getPreviousValue()
 201:   {
 202:     // Check for a previous value.
 203:     if (index > 0) 
 204:       // Return the element at the previous position.
 205:       return list.get(index - 1);
 206:     else
 207:       // Return null as this is the start of the list.
 208:       return null;
 209:     }
 210: 
 211:   /**
 212:    * Returns the current value of the model.  Initially, this will
 213:    * be the element at position 0.  On later invocations, this will
 214:    * be the last element returned by <code>getNextValue()</code>
 215:    * or <code>getPreviousValue()</code>.
 216:    *
 217:    * @return The current value.
 218:    *
 219:    * @see SpinnerListModel#getPreviousValue()
 220:    * @see SpinnerListModel#getNextValue()
 221:    */
 222:   public Object getValue()
 223:   {
 224:     return list.get(index);
 225:   }
 226: 
 227:   /**
 228:    * Changes the backing list for this model.  The model only stores
 229:    * a reference to the list, so any changes made to the list elsewhere
 230:    * will be reflected in the values returned by the model.  A
 231:    * <code>ChangeEvent</code> is fired if the list being used actually
 232:    * changes (i.e. the new list is not referentially equal (!=) to the
 233:    * old one).
 234:    *
 235:    * @param list The new list to use.
 236:    *
 237:    * @throws IllegalArgumentException if the list is null or contains
 238:    *         no elements.
 239:    *
 240:    * @see ChangeEvent
 241:    */
 242:   public void setList(List<?> list)
 243:   {
 244:     // Check for null or zero size list.
 245:     if (list == null || list.size() == 0)
 246:       throw new IllegalArgumentException("The supplied list was invalid.");
 247: 
 248:     // Check for a change of referenced list.
 249:     if (this.list != list)
 250:       {
 251:         // Store the new list.
 252:         this.list = list;
 253:         // Notify listeners of a change.
 254:         fireStateChanged();
 255:       }
 256:     // We reset the other values in either case.
 257:     // Set the index to 0.
 258:     index = 0;
 259:   }
 260: 
 261:   /**
 262:    * Sets the current value of the model to be the one supplied.
 263:    * The value must exist within the backing list in order for
 264:    * the change to take place.  Otherwise, an exception is thrown.
 265:    * The value used is the first occurrence of the value within
 266:    * the backing list.  Listeners are notified of this change.
 267:    * Following the change, <code>getNextValue()</code> and
 268:    * <code>getPreviousValue()</code> return the objects following
 269:    * and prior to the supplied value, respectively. 
 270:    *
 271:    * @param value The requested new value of the list.
 272:    *
 273:    * @throws IllegalArgumentException if the supplied value does
 274:    *         not exist in the backing list.
 275:    *
 276:    * @see SpinnerListModel#getPreviousValue()
 277:    * @see SpinnerListModel#getNextValue()
 278:    */
 279:   public void setValue(Object value)
 280:   {
 281:     int valueIndex;
 282: 
 283:     // Search for the value in the list.
 284:     valueIndex = list.indexOf(value);
 285:     // Check for the value being found.
 286:     if (valueIndex == -1)
 287:       throw new IllegalArgumentException("The supplied value does not "
 288:                                          + "exist in this list");
 289:     // Make the indices match.
 290:     index = valueIndex;
 291:     // Notify the listeners.
 292:     fireStateChanged();
 293:   }
 294: 
 295: }