libjava/java/awt/Checkbox.java

   1 /* Checkbox.java -- An AWT checkbox widget
   2    Copyright (C) 1999, 2000, 2001, 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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
  39 package java.awt;
  40
  41 import java.awt.peer.CheckboxPeer;
  42 import java.awt.peer.ComponentPeer;
  43 import java.awt.event.ItemEvent;
  44 import java.awt.event.ItemListener;
  45 import java.io.Serializable;
  46
  47 /**
  48  * This class implements a component which has an on/off state.  Two
  49  * or more Checkboxes can be grouped by a CheckboxGroup.
  50  *
  51  * @author Aaron M. Renn (arenn@urbanophile.com)
  52  * @author Tom Tromey <tromey@redhat.com>
  53  */
  54 public class Checkbox extends Component implements ItemSelectable, Serializable
  55 {
  56
  57 // FIXME: Need readObject/writeObject for this.
  58
  59 /*
  60  * Static Variables
  61  */
  62
  63 // Serialization Constant
  64 private static final long serialVersionUID = 7270714317450821763L;
  65
  66 /*************************************************************************/
  67
  68 /*
  69  * Instance Variables
  70  */
  71
  72 /**
  73   * @serial The checkbox group for this checkbox.
  74   */
  75 private CheckboxGroup group;
  76
  77 /**
  78   * @serial The label on this checkbox.
  79   */
  80 private String label;
  81
  82 /**
  83   * @serial The state of this checkbox.
  84   */
  85 private boolean state;
  86
  87 // The list of listeners for this object.
  88 private transient ItemListener item_listeners;
  89
  90 /*************************************************************************/
  91
  92 /*
  93  * Constructors
  94  */
  95
  96 /**
  97   * Initializes a new instance of <code>Checkbox</code> with no label,
  98   * an initial state of off, and that is not part of any checkbox group.
  99   */
 100 public
 101 Checkbox()
 102 {
 103   this("", false, null);
 104 }
 105
 106 /*************************************************************************/
 107
 108 /**
 109   * Initializes a new instance of <code>Checkbox</code> with the specified
 110   * label, an initial state of off, and that is not part of any checkbox
 111   * group.
 112   *
 113   * @param label The label for this checkbox.
 114   */
 115 public
 116 Checkbox(String label)
 117 {
 118   this(label, false, null);
 119 }
 120
 121 /*************************************************************************/
 122
 123 /**
 124   * Initializes a new instance of <code>Checkbox</code> with the specified
 125   * label and initial state, and that is not part of any checkbox
 126   * group.
 127   *
 128   * @param label The label for this checkbox.
 129   * @param state The initial state of the checkbox, <code>true</code> for
 130   * on, <code>false</code> for off.
 131   */
 132 public
 133 Checkbox(String label, boolean state)
 134 {
 135   this(label, state, null);
 136 }
 137
 138 /*************************************************************************/
 139
 140 /**
 141   * Initializes a new instance of <code>Checkbox</code> with the specified
 142   * label, initial state, and checkbox group.
 143   *
 144   * @param label The label for this checkbox.
 145   * @param group The checkbox group for this box, or <code>null</code>
 146   * if there is no checkbox group.
 147   * @param state The initial state of the checkbox, <code>true</code> for
 148   * on, <code>false</code> for off.
 149   */
 150 public
 151 Checkbox(String label, CheckboxGroup group, boolean state)
 152 {
 153   this(label, state, group);
 154 }
 155
 156 /*************************************************************************/
 157
 158 /**
 159   * Initializes a new instance of <code>Checkbox</code> with the specified
 160   * label, initial state, and checkbox group.
 161   *
 162   * @param label The label for this checkbox.
 163   * @param state The initial state of the checkbox, <code>true</code> for
 164   * on, <code>false</code> for off.
 165   * @param group The checkbox group for this box, or <code>null</code>
 166   * if there is no checkbox group.
 167   */
 168 public
 169 Checkbox(String label, boolean state, CheckboxGroup group)
 170 {
 171   this.label = label;
 172   this.state = state;
 173   this.group = group;
 174 }
 175
 176 /*************************************************************************/
 177
 178 /*
 179  * Instance Variables
 180  */
 181
 182 /**
 183   * Returns the label for this checkbox.
 184   *
 185   * @return The label for this checkbox.
 186   */
 187 public String
 188 getLabel()
 189 {
 190   return(label);
 191 }
 192
 193 /*************************************************************************/
 194
 195 /**
 196   * Sets the label for this checkbox to the specified value.
 197   *
 198   * @param label The new checkbox label.
 199   */
 200 public synchronized void
 201 setLabel(String label)
 202 {
 203   this.label = label;
 204   if (peer != null)
 205     {
 206       CheckboxPeer cp = (CheckboxPeer) peer;
 207       cp.setLabel(label);
 208     }
 209 }
 210
 211 /*************************************************************************/
 212
 213 /**
 214   * Returns the state of this checkbox.
 215   *
 216   * @return The state of this checkbox, which will be <code>true</code> for
 217   * on and <code>false</code> for off.
 218   */
 219 public boolean
 220 getState()
 221 {
 222   return(state);
 223 }
 224
 225 /*************************************************************************/
 226
 227 /**
 228   * Sets the state of this checkbox to the specified value.
 229   *
 230   * @param state The new state of the checkbox, which will be <code>true</code>
 231   * for on or <code>false</code> for off.
 232   */
 233 public synchronized void
 234 setState(boolean state)
 235 {
 236   this.state = state;
 237   if (peer != null)
 238     {
 239       CheckboxPeer cp = (CheckboxPeer) peer;
 240       cp.setState (state);
 241     }
 242 }
 243
 244 /*************************************************************************/
 245
 246 /**
 247   * Returns an array of length one containing the checkbox label if this
 248   * checkbox is selected.  Otherwise <code>null</code> is returned.
 249   *
 250   * @return The selection state of this checkbox.
 251   */
 252 public Object[]
 253 getSelectedObjects()
 254 {
 255   if (state == false)
 256     return(null);
 257
 258   Object[] objs = new Object[1];
 259   objs[0] = label;
 260
 261   return(objs);
 262 }
 263
 264 /*************************************************************************/
 265
 266 /**
 267   * Returns the checkbox group this object is a member of, if any.
 268   *
 269   * @return This object's checkbox group, of <code>null</code> if it is
 270   * not a member of any group.
 271   */
 272 public CheckboxGroup
 273 getCheckboxGroup()
 274 {
 275   return(group);
 276 }
 277
 278 /*************************************************************************/
 279
 280 /**
 281   * Sets this object's checkbox group to the specified group.
 282   *
 283   * @param group The new checkbox group, or <code>null</code> to make this
 284   * object part of no checkbox group.
 285   */
 286 public synchronized void
 287 setCheckboxGroup(CheckboxGroup group)
 288 {
 289   this.group = group;
 290   if (peer != null)
 291     {
 292       CheckboxPeer cp = (CheckboxPeer) peer;
 293       cp.setCheckboxGroup (group);
 294     }
 295 }
 296
 297 /*************************************************************************/
 298
 299 /**
 300   * Creates this object's native peer.
 301   */
 302 public void
 303 addNotify()
 304 {
 305   if (peer == null)
 306     peer = getToolkit ().createCheckbox (this);
 307   super.addNotify ();
 308 }
 309
 310 /*************************************************************************/
 311
 312 /**
 313   * Adds a new listeners to the list of registered listeners for this object.
 314   *
 315   * @param listener The new listener to add.
 316   */
 317 public synchronized void
 318 addItemListener(ItemListener listener)
 319 {
 320   item_listeners = AWTEventMulticaster.add(item_listeners, listener);
 321 }
 322
 323 /*************************************************************************/
 324
 325 /**
 326   * Removes a listener from the list of registered listeners for this object.
 327   *
 328   * @param listener The listener to remove.
 329   */
 330 public synchronized void
 331 removeItemListener(ItemListener listener)
 332 {
 333   item_listeners = AWTEventMulticaster.remove(item_listeners, listener);
 334 }
 335
 336 /*************************************************************************/
 337
 338 /**
 339   * Processes this event by calling <code>processItemEvent()</code> if it
 340   * is any instance of <code>ItemEvent</code>.  Otherwise it is passed to
 341   * the superclass for processing.
 342   *
 343   * @param event The event to process.
 344   */
 345 protected void
 346 processEvent(AWTEvent event)
 347 {
 348   if (event instanceof ItemEvent)
 349     processItemEvent((ItemEvent)event);
 350   else
 351     super.processEvent(event);
 352 }
 353
 354 /*************************************************************************/
 355
 356 /**
 357   * Processes this event by dispatching it to any registered listeners.
 358   *
 359   * @param event The <code>ItemEvent</code> to process.
 360   */
 361 protected void
 362 processItemEvent(ItemEvent event)
 363 {
 364   if (item_listeners != null)
 365     item_listeners.itemStateChanged(event);
 366 }
 367
 368 void
 369 dispatchEventImpl(AWTEvent e)
 370 {
 371   if (e.id <= ItemEvent.ITEM_LAST
 372       && e.id >= ItemEvent.ITEM_FIRST
 373       && (item_listeners != null
 374           || (eventMask & AWTEvent.ITEM_EVENT_MASK) != 0))
 375     processEvent(e);
 376   else
 377     super.dispatchEventImpl(e);
 378 }
 379
 380 /*************************************************************************/
 381
 382 /**
 383   * Returns a debugging string for this object.
 384   */
 385 protected String
 386 paramString()
 387 {
 388   return ("label=" + label + ",state=" + state + ",group=" + group
 389           + "," + super.paramString());
 390 }
 391
 392 } // class Checkbox