1 /*

     2  * Copyright 1997-2006 Sun Microsystems, Inc.  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.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package javax.swing;

    27 

    28 import java.awt.Component;

    29 import java.awt.Dimension;

    30 import java.awt.Graphics;

    31 import java.awt.Insets;

    32 import java.awt.Point;

    33 import java.awt.Rectangle;

    34 import java.awt.event.*;

    35 import java.util.Vector;

    36 import java.util.Enumeration;

    37 

    38 import java.io.Serializable;

    39 import java.io.ObjectOutputStream;

    40 import java.io.ObjectInputStream;

    41 import java.io.IOException;

    42 

    43 import javax.swing.event.*;

    44 import javax.swing.border.Border;

    45 import javax.swing.plaf.*;

    46 import javax.accessibility.*;

    47 

    48 /**

    49  * An implementation of a menu bar. You add <code>JMenu</code> objects to the

    50  * menu bar to construct a menu. When the user selects a <code>JMenu</code>

    51  * object, its associated <code>JPopupMenu</code> is displayed, allowing the

    52  * user to select one of the <code>JMenuItems</code> on it.

    53  * <p>

    54  * For information and examples of using menu bars see

    55  * <a

    56  href="http://java.sun.com/docs/books/tutorial/uiswing/components/menu.html">How to Use Menus</a>,

    57  * a section in <em>The Java Tutorial.</em>

    58  * <p>

    59  * <strong>Warning:</strong> Swing is not thread safe. For more

    60  * information see <a

    61  * href="package-summary.html#threading">Swing's Threading

    62  * Policy</a>.

    63  * <p>

    64  * <strong>Warning:</strong>

    65  * Serialized objects of this class will not be compatible with

    66  * future Swing releases. The current serialization support is

    67  * appropriate for short term storage or RMI between applications running

    68  * the same version of Swing.  As of 1.4, support for long term storage

    69  * of all JavaBeans<sup><font size="-2">TM</font></sup>

    70  * has been added to the <code>java.beans</code> package.

    71  * Please see {@link java.beans.XMLEncoder}.

    72  *

    73  * @beaninfo

    74  *   attribute: isContainer true

    75  * description: A container for holding and displaying menus.

    76  *

    77  * @author Georges Saab

    78  * @author David Karlton

    79  * @author Arnaud Weber

    80  * @see JMenu

    81  * @see JPopupMenu

    82  * @see JMenuItem

    83  */

    84 public class JMenuBar extends JComponent implements Accessible,MenuElement

    85 {

    86     /**

    87      * @see #getUIClassID

    88      * @see #readObject

    89      */

    90     private static final String uiClassID = "MenuBarUI";

    91 

    92     /*

    93      * Model for the selected subcontrol.

    94      */

    95     private transient SingleSelectionModel selectionModel;

    96 

    97     private boolean paintBorder           = true;

    98     private Insets     margin             = null;

    99 

   100     /* diagnostic aids -- should be false for production builds. */

   101     private static final boolean TRACE =   false; // trace creates and disposes

   102     private static final boolean VERBOSE = false; // show reuse hits/misses

   103     private static final boolean DEBUG =   false;  // show bad params, misc.

   104 

   105     /**

   106      * Creates a new menu bar.

   107      */

   108     public JMenuBar() {

   109         super();

   110         setFocusTraversalKeysEnabled(false);

   111         setSelectionModel(new DefaultSingleSelectionModel());

   112         updateUI();

   113     }

   114 

   115     /**

   116      * Returns the menubar's current UI.

   117      * @see #setUI

   118      */

   119     public MenuBarUI getUI() {

   120         return (MenuBarUI)ui;

   121     }

   122 

   123     /**

   124      * Sets the L&F object that renders this component.

   125      *

   126      * @param ui the new MenuBarUI L&F object

   127      * @see UIDefaults#getUI

   128      * @beaninfo

   129      *        bound: true

   130      *       hidden: true

   131      *    attribute: visualUpdate true

   132      *  description: The UI object that implements the Component's LookAndFeel.

   133      */

   134     public void setUI(MenuBarUI ui) {

   135         super.setUI(ui);

   136     }

   137 

   138     /**

   139      * Resets the UI property with a value from the current look and feel.

   140      *

   141      * @see JComponent#updateUI

   142      */

   143     public void updateUI() {

   144         setUI((MenuBarUI)UIManager.getUI(this));

   145     }

   146 

   147 

   148     /**

   149      * Returns the name of the L&F class that renders this component.

   150      *

   151      * @return the string "MenuBarUI"

   152      * @see JComponent#getUIClassID

   153      * @see UIDefaults#getUI

   154      */

   155     public String getUIClassID() {

   156         return uiClassID;

   157     }

   158 

   159 

   160     /**

   161      * Returns the model object that handles single selections.

   162      *

   163      * @return the <code>SingleSelectionModel</code> property

   164      * @see SingleSelectionModel

   165      */

   166     public SingleSelectionModel getSelectionModel() {

   167         return selectionModel;

   168     }

   169 

   170     /**

   171      * Sets the model object to handle single selections.

   172      *

   173      * @param model the <code>SingleSelectionModel</code> to use

   174      * @see SingleSelectionModel

   175      * @beaninfo

   176      *       bound: true

   177      * description: The selection model, recording which child is selected.

   178      */

   179     public void setSelectionModel(SingleSelectionModel model) {

   180         SingleSelectionModel oldValue = selectionModel;

   181         this.selectionModel = model;

   182         firePropertyChange("selectionModel", oldValue, selectionModel);

   183     }

   184 

   185 

   186     /**

   187      * Appends the specified menu to the end of the menu bar.

   188      *

   189      * @param c the <code>JMenu</code> component to add

   190      * @return the menu component

   191      */

   192     public JMenu add(JMenu c) {

   193         super.add(c);

   194         return c;

   195     }

   196 

   197     /**

   198      * Returns the menu at the specified position in the menu bar.

   199      *

   200      * @param index  an integer giving the position in the menu bar, where

   201      *               0 is the first position

   202      * @return the <code>JMenu</code> at that position, or <code>null</code> if

   203      *          if there is no <code>JMenu</code> at that position (ie. if

   204      *          it is a <code>JMenuItem</code>)

   205      */

   206     public JMenu getMenu(int index) {

   207         Component c = getComponentAtIndex(index);

   208         if (c instanceof JMenu)

   209             return (JMenu) c;

   210         return null;

   211     }

   212 

   213     /**

   214      * Returns the number of items in the menu bar.

   215      *

   216      * @return the number of items in the menu bar

   217      */

   218     public int getMenuCount() {

   219         return getComponentCount();

   220     }

   221 

   222     /**

   223      * Sets the help menu that appears when the user selects the

   224      * "help" option in the menu bar. This method is not yet implemented

   225      * and will throw an exception.

   226      *

   227      * @param menu the JMenu that delivers help to the user

   228      */

   229     public void setHelpMenu(JMenu menu) {

   230         throw new Error("setHelpMenu() not yet implemented.");

   231     }

   232 

   233     /**

   234      * Gets the help menu for the menu bar.  This method is not yet

   235      * implemented and will throw an exception.

   236      *

   237      * @return the <code>JMenu</code> that delivers help to the user

   238      */

   239     public JMenu getHelpMenu() {

   240         throw new Error("getHelpMenu() not yet implemented.");

   241     }

   242 

   243     /**

   244      * Returns the component at the specified index.

   245      *

   246      * @param i an integer specifying the position, where 0 is first

   247      * @return the <code>Component</code> at the position,

   248      *          or <code>null</code> for an invalid index

   249      * @deprecated replaced by <code>getComponent(int i)</code>

   250      */

   251     @Deprecated

   252     public Component getComponentAtIndex(int i) {

   253         if(i < 0 || i >= getComponentCount()) {

   254             return null;

   255         }

   256         return getComponent(i);

   257     }

   258 

   259     /**

   260      * Returns the index of the specified component.

   261      *

   262      * @param c  the <code>Component</code> to find

   263      * @return an integer giving the component's position, where 0 is first;

   264      *          or -1 if it can't be found

   265      */

   266     public int getComponentIndex(Component c) {

   267         int ncomponents = this.getComponentCount();

   268         Component[] component = this.getComponents();

   269         for (int i = 0 ; i < ncomponents ; i++) {

   270             Component comp = component[i];

   271             if (comp == c)

   272                 return i;

   273         }

   274         return -1;

   275     }

   276 

   277     /**

   278      * Sets the currently selected component, producing a

   279      * a change to the selection model.

   280      *

   281      * @param sel the <code>Component</code> to select

   282      */

   283     public void setSelected(Component sel) {

   284         SingleSelectionModel model = getSelectionModel();

   285         int index = getComponentIndex(sel);

   286         model.setSelectedIndex(index);

   287     }

   288 

   289     /**

   290      * Returns true if the menu bar currently has a component selected.

   291      *

   292      * @return true if a selection has been made, else false

   293      */

   294     public boolean isSelected() {

   295         return selectionModel.isSelected();

   296     }

   297 

   298     /**

   299      * Returns true if the menu bars border should be painted.

   300      *

   301      * @return  true if the border should be painted, else false

   302      */

   303     public boolean isBorderPainted() {

   304         return paintBorder;

   305     }

   306 

   307     /**

   308      * Sets whether the border should be painted.

   309      *

   310      * @param b if true and border property is not <code>null</code>,

   311      *          the border is painted.

   312      * @see #isBorderPainted

   313      * @beaninfo

   314      *        bound: true

   315      *    attribute: visualUpdate true

   316      *  description: Whether the border should be painted.

   317      */

   318     public void setBorderPainted(boolean b) {

   319         boolean oldValue = paintBorder;

   320         paintBorder = b;

   321         firePropertyChange("borderPainted", oldValue, paintBorder);

   322         if (b != oldValue) {

   323             revalidate();

   324             repaint();

   325         }

   326     }

   327 

   328     /**

   329      * Paints the menubar's border if <code>BorderPainted</code>

   330      * property is true.

   331      *

   332      * @param g the <code>Graphics</code> context to use for painting

   333      * @see JComponent#paint

   334      * @see JComponent#setBorder

   335      */

   336     protected void paintBorder(Graphics g) {

   337         if (isBorderPainted()) {

   338             super.paintBorder(g);

   339         }

   340     }

   341 

   342     /**

   343      * Sets the margin between the menubar's border and

   344      * its menus. Setting to <code>null</code> will cause the menubar to

   345      * use the default margins.

   346      *

   347      * @param m an Insets object containing the margin values

   348      * @see Insets

   349      * @beaninfo

   350      *        bound: true

   351      *    attribute: visualUpdate true

   352      *  description: The space between the menubar's border and its contents

   353      */

   354     public void setMargin(Insets m) {

   355         Insets old = margin;

   356         this.margin = m;

   357         firePropertyChange("margin", old, m);

   358         if (old == null || !old.equals(m)) {

   359             revalidate();

   360             repaint();

   361         }

   362     }

   363 

   364     /**

   365      * Returns the margin between the menubar's border and

   366      * its menus.  If there is no previous margin, it will create

   367      * a default margin with zero size.

   368      *

   369      * @return an <code>Insets</code> object containing the margin values

   370      * @see Insets

   371      */

   372     public Insets getMargin() {

   373         if(margin == null) {

   374             return new Insets(0,0,0,0);

   375         } else {

   376             return margin;

   377         }

   378     }

   379 

   380 

   381     /**

   382      * Implemented to be a <code>MenuElement</code> -- does nothing.

   383      *

   384      * @see #getSubElements

   385      */

   386     public void processMouseEvent(MouseEvent event,MenuElement path[],MenuSelectionManager manager) {

   387     }

   388 

   389     /**

   390      * Implemented to be a <code>MenuElement</code> -- does nothing.

   391      *

   392      * @see #getSubElements

   393      */

   394     public void processKeyEvent(KeyEvent e,MenuElement path[],MenuSelectionManager manager) {

   395     }

   396 

   397     /**

   398      * Implemented to be a <code>MenuElement</code> -- does nothing.

   399      *

   400      * @see #getSubElements

   401      */

   402     public void menuSelectionChanged(boolean isIncluded) {

   403     }

   404 

   405     /**

   406      * Implemented to be a <code>MenuElement</code> -- returns the

   407      * menus in this menu bar.

   408      * This is the reason for implementing the <code>MenuElement</code>

   409      * interface -- so that the menu bar can be treated the same as

   410      * other menu elements.

   411      * @return an array of menu items in the menu bar.

   412      */

   413     public MenuElement[] getSubElements() {

   414         MenuElement result[];

   415         Vector tmp = new Vector();

   416         int c = getComponentCount();

   417         int i;

   418         Component m;

   419 

   420         for(i=0 ; i < c ; i++) {

   421             m = getComponent(i);

   422             if(m instanceof MenuElement)

   423                 tmp.addElement(m);

   424         }

   425 

   426         result = new MenuElement[tmp.size()];

   427         for(i=0,c=tmp.size() ; i < c ; i++)

   428             result[i] = (MenuElement) tmp.elementAt(i);

   429         return result;

   430     }

   431 

   432     /**

   433      * Implemented to be a <code>MenuElement</code>. Returns this object.

   434      *

   435      * @return the current <code>Component</code> (this)

   436      * @see #getSubElements

   437      */

   438     public Component getComponent() {

   439         return this;

   440     }

   441 

   442 

   443     /**

   444      * Returns a string representation of this <code>JMenuBar</code>.

   445      * This method

   446      * is intended to be used only for debugging purposes, and the

   447      * content and format of the returned string may vary between

   448      * implementations. The returned string may be empty but may not

   449      * be <code>null</code>.

   450      *

   451      * @return  a string representation of this <code>JMenuBar</code>

   452      */

   453     protected String paramString() {

   454         String paintBorderString = (paintBorder ?

   455                                     "true" : "false");

   456         String marginString = (margin != null ?

   457                                margin.toString() : "");

   458 

   459         return super.paramString() +

   460         ",margin=" + marginString +

   461         ",paintBorder=" + paintBorderString;

   462     }

   463 

   464 /////////////////

   465 // Accessibility support

   466 ////////////////

   467 

   468     /**

   469      * Gets the AccessibleContext associated with this JMenuBar.

   470      * For JMenuBars, the AccessibleContext takes the form of an

   471      * AccessibleJMenuBar.

   472      * A new AccessibleJMenuBar instance is created if necessary.

   473      *

   474      * @return an AccessibleJMenuBar that serves as the

   475      *         AccessibleContext of this JMenuBar

   476      */

   477     public AccessibleContext getAccessibleContext() {

   478         if (accessibleContext == null) {

   479             accessibleContext = new AccessibleJMenuBar();

   480         }

   481         return accessibleContext;

   482     }

   483 

   484     /**

   485      * This class implements accessibility support for the

   486      * <code>JMenuBar</code> class.  It provides an implementation of the

   487      * Java Accessibility API appropriate to menu bar user-interface

   488      * elements.

   489      * <p>

   490      * <strong>Warning:</strong>

   491      * Serialized objects of this class will not be compatible with

   492      * future Swing releases. The current serialization support is

   493      * appropriate for short term storage or RMI between applications running

   494      * the same version of Swing.  As of 1.4, support for long term storage

   495      * of all JavaBeans<sup><font size="-2">TM</font></sup>

   496      * has been added to the <code>java.beans</code> package.

   497      * Please see {@link java.beans.XMLEncoder}.

   498      */

   499     protected class AccessibleJMenuBar extends AccessibleJComponent

   500         implements AccessibleSelection {

   501 

   502         /**

   503          * Get the accessible state set of this object.

   504          *

   505          * @return an instance of AccessibleState containing the current state

   506          *         of the object

   507          */

   508         public AccessibleStateSet getAccessibleStateSet() {

   509             AccessibleStateSet states = super.getAccessibleStateSet();

   510             return states;

   511         }

   512 

   513         /**

   514          * Get the role of this object.

   515          *

   516          * @return an instance of AccessibleRole describing the role of the

   517          * object

   518          */

   519         public AccessibleRole getAccessibleRole() {

   520             return AccessibleRole.MENU_BAR;

   521         }

   522 

   523         /**

   524          * Get the AccessibleSelection associated with this object.  In the

   525          * implementation of the Java Accessibility API for this class,

   526          * return this object, which is responsible for implementing the

   527          * AccessibleSelection interface on behalf of itself.

   528          *

   529          * @return this object

   530          */

   531         public AccessibleSelection getAccessibleSelection() {

   532             return this;

   533         }

   534 

   535         /**

   536          * Returns 1 if a menu is currently selected in this menu bar.

   537          *

   538          * @return 1 if a menu is currently selected, else 0

   539          */

   540          public int getAccessibleSelectionCount() {

   541             if (isSelected()) {

   542                 return 1;

   543             } else {

   544                 return 0;

   545             }

   546          }

   547 

   548         /**

   549          * Returns the currently selected menu if one is selected,

   550          * otherwise null.

   551          */

   552          public Accessible getAccessibleSelection(int i) {

   553             if (isSelected()) {

   554                 if (i != 0) {   // single selection model for JMenuBar

   555                     return null;

   556                 }

   557                 int j = getSelectionModel().getSelectedIndex();

   558                 if (getComponentAtIndex(j) instanceof Accessible) {

   559                     return (Accessible) getComponentAtIndex(j);

   560                 }

   561             }

   562             return null;

   563          }

   564 

   565         /**

   566          * Returns true if the current child of this object is selected.

   567          *

   568          * @param i the zero-based index of the child in this Accessible

   569          * object.

   570          * @see AccessibleContext#getAccessibleChild

   571          */

   572         public boolean isAccessibleChildSelected(int i) {

   573             return (i == getSelectionModel().getSelectedIndex());

   574         }

   575 

   576         /**

   577          * Selects the nth menu in the menu bar, forcing it to

   578          * pop up.  If another menu is popped up, this will force

   579          * it to close.  If the nth menu is already selected, this

   580          * method has no effect.

   581          *

   582          * @param i the zero-based index of selectable items

   583          * @see #getAccessibleStateSet

   584          */

   585         public void addAccessibleSelection(int i) {

   586             // first close up any open menu

   587             int j = getSelectionModel().getSelectedIndex();

   588             if (i == j) {

   589                 return;

   590             }

   591             if (j >= 0 && j < getMenuCount()) {

   592                 JMenu menu = getMenu(j);

   593                 if (menu != null) {

   594                     MenuSelectionManager.defaultManager().setSelectedPath(null);

   595 //                  menu.setPopupMenuVisible(false);

   596                 }

   597             }

   598             // now popup the new menu

   599             getSelectionModel().setSelectedIndex(i);

   600             JMenu menu = getMenu(i);

   601             if (menu != null) {

   602                 MenuElement me[] = new MenuElement[3];

   603                 me[0] = JMenuBar.this;

   604                 me[1] = menu;

   605                 me[2] = menu.getPopupMenu();

   606                 MenuSelectionManager.defaultManager().setSelectedPath(me);

   607 //              menu.setPopupMenuVisible(true);

   608             }

   609         }

   610 

   611         /**

   612          * Removes the nth selected item in the object from the object's

   613          * selection.  If the nth item isn't currently selected, this

   614          * method has no effect.  Otherwise, it closes the popup menu.

   615          *

   616          * @param i the zero-based index of selectable items

   617          */

   618         public void removeAccessibleSelection(int i) {

   619             if (i >= 0 && i < getMenuCount()) {

   620                 JMenu menu = getMenu(i);

   621                 if (menu != null) {

   622                     MenuSelectionManager.defaultManager().setSelectedPath(null);

   623 //                  menu.setPopupMenuVisible(false);

   624                 }

   625                 getSelectionModel().setSelectedIndex(-1);

   626             }

   627         }

   628 

   629         /**

   630          * Clears the selection in the object, so that nothing in the

   631          * object is selected.  This will close any open menu.

   632          */

   633         public void clearAccessibleSelection() {

   634             int i = getSelectionModel().getSelectedIndex();

   635             if (i >= 0 && i < getMenuCount()) {

   636                 JMenu menu = getMenu(i);

   637                 if (menu != null) {

   638                     MenuSelectionManager.defaultManager().setSelectedPath(null);

   639 //                  menu.setPopupMenuVisible(false);

   640                 }

   641             }

   642             getSelectionModel().setSelectedIndex(-1);

   643         }

   644 

   645         /**

   646          * Normally causes every selected item in the object to be selected

   647          * if the object supports multiple selections.  This method

   648          * makes no sense in a menu bar, and so does nothing.

   649          */

   650         public void selectAllAccessibleSelection() {

   651         }

   652     } // internal class AccessibleJMenuBar

   653 

   654 

   655     /**

   656      * Subclassed to check all the child menus.

   657      * @since 1.3

   658      */

   659     protected boolean processKeyBinding(KeyStroke ks, KeyEvent e,

   660                                         int condition, boolean pressed) {

   661         // See if we have a local binding.

   662         boolean retValue = super.processKeyBinding(ks, e, condition, pressed);

   663         if (!retValue) {

   664             MenuElement[] subElements = getSubElements();

   665             for (int i=0; i<subElements.length; i++) {

   666                 if (processBindingForKeyStrokeRecursive(

   667                                                         subElements[i], ks, e, condition, pressed)) {

   668                     return true;

   669                 }

   670             }

   671         }

   672         return retValue;

   673     }

   674 

   675     static boolean processBindingForKeyStrokeRecursive(MenuElement elem,

   676                                                        KeyStroke ks, KeyEvent e, int condition, boolean pressed) {

   677         if (elem == null) {

   678             return false;

   679         }

   680 

   681         Component c = elem.getComponent();

   682 

   683         if ( !(c.isVisible() || (c instanceof JPopupMenu)) || !c.isEnabled() ) {

   684             return false;

   685         }

   686 

   687         if (c != null && c instanceof JComponent &&

   688             ((JComponent)c).processKeyBinding(ks, e, condition, pressed)) {

   689 

   690             return true;

   691         }

   692 

   693         MenuElement[] subElements = elem.getSubElements();

   694         for(int i=0; i<subElements.length; i++) {

   695             if (processBindingForKeyStrokeRecursive(subElements[i], ks, e,

   696                                                     condition, pressed)) {

   697                 return true;

   698                 // We don't, pass along to children JMenu's

   699             }

   700         }

   701         return false;

   702     }

   703 

   704     /**

   705      * Overrides <code>JComponent.addNotify</code> to register this

   706      * menu bar with the current keyboard manager.

   707      */

   708     public void addNotify() {

   709         super.addNotify();

   710         KeyboardManager.getCurrentManager().registerMenuBar(this);

   711     }

   712 

   713     /**

   714      * Overrides <code>JComponent.removeNotify</code> to unregister this

   715      * menu bar with the current keyboard manager.

   716      */

   717     public void removeNotify() {

   718         super.removeNotify();

   719         KeyboardManager.getCurrentManager().unregisterMenuBar(this);

   720     }

   721 

   722 

   723     private void writeObject(ObjectOutputStream s) throws IOException {

   724         s.defaultWriteObject();

   725         if (getUIClassID().equals(uiClassID)) {

   726             byte count = JComponent.getWriteObjCounter(this);

   727             JComponent.setWriteObjCounter(this, --count);

   728             if (count == 0 && ui != null) {

   729                 ui.installUI(this);

   730             }

   731         }

   732 

   733         Object[] kvData = new Object[4];

   734         int n = 0;

   735 

   736         if (selectionModel instanceof Serializable) {

   737             kvData[n++] = "selectionModel";

   738             kvData[n++] = selectionModel;

   739         }

   740 

   741         s.writeObject(kvData);

   742     }

   743 

   744 

   745     /**

   746      * See JComponent.readObject() for information about serialization

   747      * in Swing.

   748      */

   749     private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException

   750     {

   751         s.defaultReadObject();

   752         Object[] kvData = (Object[])(s.readObject());

   753 

   754         for(int i = 0; i < kvData.length; i += 2) {

   755             if (kvData[i] == null) {

   756                 break;

   757             }

   758             else if (kvData[i].equals("selectionModel")) {

   759                 selectionModel = (SingleSelectionModel)kvData[i + 1];

   760             }

   761         }

   762 

   763     }

   764 }