1 /*
   2  * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package javax.swing;
  26 
  27 import java.util.EventListener;
  28 
  29 import java.awt.*;
  30 import java.awt.event.*;
  31 import java.awt.image.*;
  32 
  33 import java.io.ObjectOutputStream;
  34 import java.io.ObjectInputStream;
  35 import java.io.IOException;
  36 
  37 import javax.swing.plaf.*;
  38 import javax.accessibility.*;
  39 
  40 
  41 /**
  42  * A menu item that can be selected or deselected. If selected, the menu
  43  * item typically appears with a checkmark next to it. If unselected or
  44  * deselected, the menu item appears without a checkmark. Like a regular
  45  * menu item, a check box menu item can have either text or a graphic
  46  * icon associated with it, or both.
  47  * <p>
  48  * Either <code>isSelected</code>/<code>setSelected</code> or
  49  * <code>getState</code>/<code>setState</code> can be used
  50  * to determine/specify the menu item's selection state. The
  51  * preferred methods are <code>isSelected</code> and
  52  * <code>setSelected</code>, which work for all menus and buttons.
  53  * The <code>getState</code> and <code>setState</code> methods exist for
  54  * compatibility with other component sets.
  55  * <p>
  56  * Menu items can be configured, and to some degree controlled, by
  57  * <code><a href="Action.html">Action</a></code>s.  Using an
  58  * <code>Action</code> with a menu item has many benefits beyond directly
  59  * configuring a menu item.  Refer to <a href="Action.html#buttonActions">
  60  * Swing Components Supporting <code>Action</code></a> for more
  61  * details, and you can find more information in <a
  62  * href="http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html">How
  63  * to Use Actions</a>, a section in <em>The Java Tutorial</em>.
  64  * <p>
  65  * For further information and examples of using check box menu items,
  66  * see <a
  67  href="http://docs.oracle.com/javase/tutorial/uiswing/components/menu.html">How to Use Menus</a>,
  68  * a section in <em>The Java Tutorial.</em>
  69  * <p>
  70  * <strong>Warning:</strong> Swing is not thread safe. For more
  71  * information see <a
  72  * href="package-summary.html#threading">Swing's Threading
  73  * Policy</a>.
  74  * <p>
  75  * <strong>Warning:</strong>
  76  * Serialized objects of this class will not be compatible with
  77  * future Swing releases. The current serialization support is
  78  * appropriate for short term storage or RMI between applications running
  79  * the same version of Swing.  As of 1.4, support for long term storage
  80  * of all JavaBeans<sup><font size="-2">TM</font></sup>
  81  * has been added to the <code>java.beans</code> package.
  82  * Please see {@link java.beans.XMLEncoder}.
  83  *
  84  * @beaninfo
  85  *   attribute: isContainer false
  86  * description: A menu item which can be selected or deselected.
  87  *
  88  * @author Georges Saab
  89  * @author David Karlton
  90  */
  91 public class JCheckBoxMenuItem extends JMenuItem implements SwingConstants,
  92         Accessible
  93 {
  94     /**
  95      * @see #getUIClassID
  96      * @see #readObject
  97      */
  98     private static final String uiClassID = "CheckBoxMenuItemUI";
  99 
 100     /**
 101      * Creates an initially unselected check box menu item with no set text or icon.
 102      */
 103     public JCheckBoxMenuItem() {
 104         this(null, null, false);
 105     }
 106 
 107     /**
 108      * Creates an initially unselected check box menu item with an icon.
 109      *
 110      * @param icon the icon of the CheckBoxMenuItem.
 111      */
 112     public JCheckBoxMenuItem(Icon icon) {
 113         this(null, icon, false);
 114     }
 115 
 116     /**
 117      * Creates an initially unselected check box menu item with text.
 118      *
 119      * @param text the text of the CheckBoxMenuItem
 120      */
 121     public JCheckBoxMenuItem(String text) {
 122         this(text, null, false);
 123     }
 124 
 125     /**
 126      * Creates a menu item whose properties are taken from the
 127      * Action supplied.
 128      *
 129      * @since 1.3
 130      */
 131     public JCheckBoxMenuItem(Action a) {
 132         this();
 133         setAction(a);
 134     }
 135 
 136     /**
 137      * Creates an initially unselected check box menu item with the specified text and icon.
 138      *
 139      * @param text the text of the CheckBoxMenuItem
 140      * @param icon the icon of the CheckBoxMenuItem
 141      */
 142     public JCheckBoxMenuItem(String text, Icon icon) {
 143         this(text, icon, false);
 144     }
 145 
 146     /**
 147      * Creates a check box menu item with the specified text and selection state.
 148      *
 149      * @param text the text of the check box menu item.
 150      * @param b the selected state of the check box menu item
 151      */
 152     public JCheckBoxMenuItem(String text, boolean b) {
 153         this(text, null, b);
 154     }
 155 
 156     /**
 157      * Creates a check box menu item with the specified text, icon, and selection state.
 158      *
 159      * @param text the text of the check box menu item
 160      * @param icon the icon of the check box menu item
 161      * @param b the selected state of the check box menu item
 162      */
 163     public JCheckBoxMenuItem(String text, Icon icon, boolean b) {
 164         super(text, icon);
 165         setModel(new JToggleButton.ToggleButtonModel());
 166         setSelected(b);
 167         setFocusable(false);
 168     }
 169 
 170     /**
 171      * Returns the name of the L&amp;F class
 172      * that renders this component.
 173      *
 174      * @return "CheckBoxMenuItemUI"
 175      * @see JComponent#getUIClassID
 176      * @see UIDefaults#getUI
 177      */
 178     public String getUIClassID() {
 179         return uiClassID;
 180     }
 181 
 182      /**
 183       * Returns the selected-state of the item. This method
 184       * exists for AWT compatibility only.  New code should
 185       * use isSelected() instead.
 186       *
 187       * @return true  if the item is selected
 188       */
 189     public boolean getState() {
 190         return isSelected();
 191     }
 192 
 193     /**
 194      * Sets the selected-state of the item. This method
 195      * exists for AWT compatibility only.  New code should
 196      * use setSelected() instead.
 197      *
 198      * @param b  a boolean value indicating the item's
 199      *           selected-state, where true=selected
 200      * @beaninfo
 201      * description: The selection state of the check box menu item
 202      *      hidden: true
 203      */
 204     public synchronized void setState(boolean b) {
 205         setSelected(b);
 206     }
 207 
 208 
 209     /**
 210      * Returns an array (length 1) containing the check box menu item
 211      * label or null if the check box is not selected.
 212      *
 213      * @return an array containing one Object -- the text of the menu item
 214      *         -- if the item is selected; otherwise null
 215      */
 216     public Object[] getSelectedObjects() {
 217         if (isSelected() == false)
 218             return null;
 219         Object[] selectedObjects = new Object[1];
 220         selectedObjects[0] = getText();
 221         return selectedObjects;
 222     }
 223 
 224     /**
 225      * See readObject() and writeObject() in JComponent for more
 226      * information about serialization in Swing.
 227      */
 228     private void writeObject(ObjectOutputStream s) throws IOException {
 229         s.defaultWriteObject();
 230         if (getUIClassID().equals(uiClassID)) {
 231             byte count = JComponent.getWriteObjCounter(this);
 232             JComponent.setWriteObjCounter(this, --count);
 233             if (count == 0 && ui != null) {
 234                 ui.installUI(this);
 235             }
 236         }
 237     }
 238 
 239 
 240     /**
 241      * Returns a string representation of this JCheckBoxMenuItem. This method
 242      * is intended to be used only for debugging purposes, and the
 243      * content and format of the returned string may vary between
 244      * implementations. The returned string may be empty but may not
 245      * be <code>null</code>.
 246      *
 247      * @return  a string representation of this JCheckBoxMenuItem.
 248      */
 249     protected String paramString() {
 250         return super.paramString();
 251     }
 252 
 253     /**
 254      * Overriden to return true, JCheckBoxMenuItem supports
 255      * the selected state.
 256      */
 257     boolean shouldUpdateSelectedStateFromAction() {
 258         return true;
 259     }
 260 
 261 /////////////////
 262 // Accessibility support
 263 ////////////////
 264 
 265     /**
 266      * Gets the AccessibleContext associated with this JCheckBoxMenuItem.
 267      * For JCheckBoxMenuItems, the AccessibleContext takes the form of an
 268      * AccessibleJCheckBoxMenuItem.
 269      * A new AccessibleJCheckBoxMenuItem instance is created if necessary.
 270      *
 271      * @return an AccessibleJCheckBoxMenuItem that serves as the
 272      *         AccessibleContext of this AccessibleJCheckBoxMenuItem
 273      */
 274     public AccessibleContext getAccessibleContext() {
 275         if (accessibleContext == null) {
 276             accessibleContext = new AccessibleJCheckBoxMenuItem();
 277         }
 278         return accessibleContext;
 279     }
 280 
 281     /**
 282      * This class implements accessibility support for the
 283      * <code>JCheckBoxMenuItem</code> class.  It provides an implementation
 284      * of the Java Accessibility API appropriate to checkbox menu item
 285      * user-interface elements.
 286      * <p>
 287      * <strong>Warning:</strong>
 288      * Serialized objects of this class will not be compatible with
 289      * future Swing releases. The current serialization support is
 290      * appropriate for short term storage or RMI between applications running
 291      * the same version of Swing.  As of 1.4, support for long term storage
 292      * of all JavaBeans<sup><font size="-2">TM</font></sup>
 293      * has been added to the <code>java.beans</code> package.
 294      * Please see {@link java.beans.XMLEncoder}.
 295      */
 296     protected class AccessibleJCheckBoxMenuItem extends AccessibleJMenuItem {
 297         /**
 298          * Get the role of this object.
 299          *
 300          * @return an instance of AccessibleRole describing the role of the
 301          * object
 302          */
 303         public AccessibleRole getAccessibleRole() {
 304             return AccessibleRole.CHECK_BOX;
 305         }
 306     } // inner class AccessibleJCheckBoxMenuItem
 307 }