001 /* Choice.java -- Java choice button widget.
002 Copyright (C) 1999, 2000, 2001, 2002, 2004, 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import java.awt.event.ItemEvent;
042 import java.awt.event.ItemListener;
043 import java.awt.peer.ChoicePeer;
044 import java.io.Serializable;
045 import java.util.EventListener;
046 import java.util.Vector;
047
048 import javax.accessibility.Accessible;
049 import javax.accessibility.AccessibleAction;
050 import javax.accessibility.AccessibleContext;
051 import javax.accessibility.AccessibleRole;
052
053 /**
054 * This class implements a drop down choice list.
055 *
056 * @author Aaron M. Renn (arenn@urbanophile.com)
057 */
058 public class Choice extends Component
059 implements ItemSelectable, Serializable, Accessible
060 {
061 /**
062 * The number used to generate the name returned by getName.
063 */
064 private static transient long next_choice_number;
065
066 // Serialization constant
067 private static final long serialVersionUID = -4075310674757313071L;
068
069 /**
070 * @serial A list of items for the choice box, which can be <code>null</code>.
071 * This is package-private to avoid an accessor method.
072 */
073 Vector pItems = new Vector();
074
075 /**
076 * @serial The index of the selected item in the choice box.
077 */
078 private int selectedIndex = -1;
079
080 /**
081 * ItemListener chain
082 */
083 private ItemListener item_listeners;
084
085 /**
086 * This class provides accessibility support for the
087 * combo box.
088 *
089 * @author Jerry Quinn (jlquinn@optonline.net)
090 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
091 */
092 protected class AccessibleAWTChoice
093 extends AccessibleAWTComponent
094 implements AccessibleAction
095 {
096
097 /**
098 * Serialization constant to match JDK 1.5
099 */
100 private static final long serialVersionUID = 7175603582428509322L;
101
102 /**
103 * Default constructor which simply calls the
104 * super class for generic component accessibility
105 * handling.
106 */
107 public AccessibleAWTChoice()
108 {
109 super();
110 }
111
112 /**
113 * Returns an implementation of the <code>AccessibleAction</code>
114 * interface for this accessible object. In this case, the
115 * current instance is simply returned (with a more appropriate
116 * type), as it also implements the accessible action as well as
117 * the context.
118 *
119 * @return the accessible action associated with this context.
120 * @see javax.accessibility.AccessibleAction
121 */
122 public AccessibleAction getAccessibleAction()
123 {
124 return this;
125 }
126
127 /**
128 * Returns the role of this accessible object.
129 *
130 * @return the instance of <code>AccessibleRole</code>,
131 * which describes this object.
132 * @see javax.accessibility.AccessibleRole
133 */
134 public AccessibleRole getAccessibleRole()
135 {
136 return AccessibleRole.COMBO_BOX;
137 }
138
139 /**
140 * Returns the number of actions associated with this accessible
141 * object. In this case, it is the number of choices available.
142 *
143 * @return the number of choices available.
144 * @see javax.accessibility.AccessibleAction#getAccessibleActionCount()
145 */
146 public int getAccessibleActionCount()
147 {
148 return pItems.size();
149 }
150
151 /**
152 * Returns a description of the action with the supplied id.
153 * In this case, it is the text used in displaying the particular
154 * choice on-screen.
155 *
156 * @param i the id of the choice whose description should be
157 * retrieved.
158 * @return the <code>String</code> used to describe the choice.
159 * @see javax.accessibility.AccessibleAction#getAccessibleActionDescription(int)
160 */
161 public String getAccessibleActionDescription(int i)
162 {
163 return (String) pItems.get(i);
164 }
165
166 /**
167 * Executes the action with the specified id. In this case,
168 * calling this method provides the same behaviour as would
169 * choosing a choice from the list in a visual manner.
170 *
171 * @param i the id of the choice to select.
172 * @return true if a valid choice was specified.
173 * @see javax.accessibility.AccessibleAction#doAccessibleAction(int)
174 */
175 public boolean doAccessibleAction(int i)
176 {
177 if (i < 0 || i >= pItems.size())
178 return false;
179
180 Choice.this.select( i );
181
182 return true;
183 }
184 }
185
186 /**
187 * Initializes a new instance of <code>Choice</code>.
188 *
189 * @exception HeadlessException If GraphicsEnvironment.isHeadless()
190 * returns true
191 */
192 public Choice()
193 {
194 if (GraphicsEnvironment.isHeadless())
195 throw new HeadlessException ();
196 }
197
198 /**
199 * Returns the number of items in the list.
200 *
201 * @return The number of items in the list.
202 */
203 public int getItemCount()
204 {
205 return countItems ();
206 }
207
208 /**
209 * Returns the number of items in the list.
210 *
211 * @return The number of items in the list.
212 *
213 * @deprecated This method is deprecated in favor of <code>getItemCount</code>.
214 */
215 public int countItems()
216 {
217 return pItems.size();
218 }
219
220 /**
221 * Returns the item at the specified index in the list.
222 *
223 * @param index The index into the list to return the item from.
224 *
225 * @exception ArrayIndexOutOfBoundsException If the index is invalid.
226 */
227 public String getItem(int index)
228 {
229 return (String)pItems.elementAt(index);
230 }
231
232 /**
233 * Adds the specified item to this choice box.
234 *
235 * @param item The item to add.
236 *
237 * @exception NullPointerException If the item's value is null
238 *
239 * @since 1.1
240 */
241 public synchronized void add(String item)
242 {
243 if (item == null)
244 throw new NullPointerException ("item must be non-null");
245
246 pItems.addElement(item);
247
248 if (peer != null)
249 ((ChoicePeer) peer).add(item, getItemCount() - 1);
250
251 if (selectedIndex == -1)
252 select( 0 );
253 }
254
255 /**
256 * Adds the specified item to this choice box.
257 *
258 * This method is oboslete since Java 2 platform 1.1. Please use
259 * {@link #add(String)} instead.
260 *
261 * @param item The item to add.
262 *
263 * @exception NullPointerException If the item's value is equal to null
264 */
265 public synchronized void addItem(String item)
266 {
267 add(item);
268 }
269
270 /** Inserts an item into this Choice. Existing items are shifted
271 * upwards. If the new item is the only item, then it is selected.
272 * If the currently selected item is shifted, then the first item is
273 * selected. If the currently selected item is not shifted, then it
274 * remains selected.
275 *
276 * @param item The item to add.
277 * @param index The index at which the item should be inserted.
278 *
279 * @exception IllegalArgumentException If index is less than 0
280 */
281 public synchronized void insert(String item, int index)
282 {
283 if (index < 0)
284 throw new IllegalArgumentException ("index may not be less then 0");
285
286 if (index > getItemCount ())
287 index = getItemCount ();
288
289 pItems.insertElementAt(item, index);
290
291 if (peer != null)
292 ((ChoicePeer) peer).add (item, index);
293
294 if (selectedIndex == -1 || selectedIndex >= index)
295 select(0);
296 }
297
298 /**
299 * Removes the specified item from the choice box.
300 *
301 * @param item The item to remove.
302 *
303 * @exception IllegalArgumentException If the specified item doesn't exist.
304 */
305 public synchronized void remove(String item)
306 {
307 int index = pItems.indexOf(item);
308 if (index == -1)
309 throw new IllegalArgumentException ("item \""
310 + item + "\" not found in Choice");
311 remove(index);
312 }
313
314 /**
315 * Removes the item at the specified index from the choice box.
316 *
317 * @param index The index of the item to remove.
318 *
319 * @exception IndexOutOfBoundsException If the index is not valid.
320 */
321 public synchronized void remove(int index)
322 {
323 pItems.removeElementAt(index);
324
325 if (peer != null)
326 ((ChoicePeer) peer).remove( index );
327
328 if( getItemCount() == 0 )
329 selectedIndex = -1;
330 else
331 {
332 if( selectedIndex > index )
333 selectedIndex--;
334 else if( selectedIndex == index )
335 selectedIndex = 0;
336
337 if( peer != null )
338 ((ChoicePeer)peer).select( selectedIndex );
339 }
340 }
341
342 /**
343 * Removes all of the objects from this choice box.
344 */
345 public synchronized void removeAll()
346 {
347 if (getItemCount() <= 0)
348 return;
349
350 pItems.removeAllElements ();
351
352 if (peer != null)
353 {
354 ChoicePeer cp = (ChoicePeer) peer;
355 cp.removeAll ();
356 }
357
358 selectedIndex = -1;
359 }
360
361 /**
362 * Returns the currently selected item, or null if no item is
363 * selected.
364 *
365 * @return The currently selected item.
366 */
367 public synchronized String getSelectedItem()
368 {
369 return (selectedIndex == -1
370 ? null
371 : ((String)pItems.elementAt(selectedIndex)));
372 }
373
374 /**
375 * Returns an array with one row containing the selected item.
376 *
377 * @return An array containing the selected item.
378 */
379 public synchronized Object[] getSelectedObjects()
380 {
381 if (selectedIndex == -1)
382 return null;
383
384 Object[] objs = new Object[1];
385 objs[0] = pItems.elementAt(selectedIndex);
386
387 return objs;
388 }
389
390 /**
391 * Returns the index of the selected item.
392 *
393 * @return The index of the selected item.
394 */
395 public int getSelectedIndex()
396 {
397 return selectedIndex;
398 }
399
400 /**
401 * Forces the item at the specified index to be selected.
402 *
403 * @param index The index of the row to make selected.
404 *
405 * @exception IllegalArgumentException If the specified index is invalid.
406 */
407 public synchronized void select(int index)
408 {
409 if ((index < 0) || (index >= getItemCount()))
410 throw new IllegalArgumentException("Bad index: " + index);
411
412 if( selectedIndex == index )
413 return;
414
415 selectedIndex = index;
416 if( peer != null )
417 ((ChoicePeer)peer).select( index );
418 }
419
420 /**
421 * Forces the named item to be selected.
422 *
423 * @param item The item to be selected.
424 *
425 * @exception IllegalArgumentException If the specified item does not exist.
426 */
427 public synchronized void select(String item)
428 {
429 int index = pItems.indexOf(item);
430 if( index >= 0 )
431 select( index );
432 }
433
434 /**
435 * Creates the native peer for this object.
436 */
437 public void addNotify()
438 {
439 if (peer == null)
440 peer = getToolkit ().createChoice (this);
441 super.addNotify ();
442 }
443
444 /**
445 * Adds the specified listener to the list of registered listeners for
446 * this object.
447 *
448 * @param listener The listener to add.
449 */
450 public synchronized void addItemListener(ItemListener listener)
451 {
452 item_listeners = AWTEventMulticaster.add(item_listeners, listener);
453 }
454
455 /**
456 * Removes the specified listener from the list of registered listeners for
457 * this object.
458 *
459 * @param listener The listener to remove.
460 */
461 public synchronized void removeItemListener(ItemListener listener)
462 {
463 item_listeners = AWTEventMulticaster.remove(item_listeners, listener);
464 }
465
466 /**
467 * Processes this event by invoking <code>processItemEvent()</code> if the
468 * event is an instance of <code>ItemEvent</code>, otherwise the event
469 * is passed to the superclass.
470 *
471 * @param event The event to process.
472 */
473 protected void processEvent(AWTEvent event)
474 {
475 if (event instanceof ItemEvent)
476 processItemEvent((ItemEvent)event);
477 else
478 super.processEvent(event);
479 }
480
481 void dispatchEventImpl(AWTEvent e)
482 {
483 super.dispatchEventImpl(e);
484
485 if( e.id <= ItemEvent.ITEM_LAST && e.id >= ItemEvent.ITEM_FIRST &&
486 ( item_listeners != null ||
487 ( eventMask & AWTEvent.ITEM_EVENT_MASK ) != 0 ) )
488 processEvent(e);
489 }
490
491 /**
492 * Processes item event by dispatching to any registered listeners.
493 *
494 * @param event The event to process.
495 */
496 protected void processItemEvent(ItemEvent event)
497 {
498 int index = pItems.indexOf((String) event.getItem());
499 if (item_listeners != null)
500 item_listeners.itemStateChanged(event);
501 }
502
503 /**
504 * Returns a debugging string for this object.
505 *
506 * @return A debugging string for this object.
507 */
508 protected String paramString()
509 {
510 return "selectedIndex=" + selectedIndex + "," + super.paramString();
511 }
512
513 /**
514 * Returns an array of all the objects currently registered as FooListeners
515 * upon this Choice. FooListeners are registered using the addFooListener
516 * method.
517 *
518 * @exception ClassCastException If listenerType doesn't specify a class or
519 * interface that implements java.util.EventListener.
520 *
521 * @since 1.3
522 */
523 public <T extends EventListener> T[] getListeners (Class<T> listenerType)
524 {
525 if (listenerType == ItemListener.class)
526 return AWTEventMulticaster.getListeners (item_listeners, listenerType);
527
528 return super.getListeners (listenerType);
529 }
530
531 /**
532 * Returns all registered item listeners.
533 *
534 * @since 1.4
535 */
536 public ItemListener[] getItemListeners ()
537 {
538 return (ItemListener[]) getListeners (ItemListener.class);
539 }
540
541 /**
542 * Gets the AccessibleContext associated with this <code>Choice</code>.
543 * The context is created, if necessary.
544 *
545 * @return the associated context
546 */
547 public AccessibleContext getAccessibleContext()
548 {
549 /* Create the context if this is the first request */
550 if (accessibleContext == null)
551 accessibleContext = new AccessibleAWTChoice();
552 return accessibleContext;
553 }
554
555 /**
556 * Generate a unique name for this <code>Choice</code>.
557 *
558 * @return A unique name for this <code>Choice</code>.
559 */
560 String generateName()
561 {
562 return "choice" + getUniqueLong();
563 }
564
565 private static synchronized long getUniqueLong()
566 {
567 return next_choice_number++;
568 }
569 } // class Choice