1 /*
   2  * Copyright (c) 1997, 2017, 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.awt.*;
  28 import java.awt.event.*;
  29 
  30 import java.util.Vector;
  31 import java.util.Locale;
  32 import java.util.ArrayList;
  33 import java.util.Collections;
  34 import java.util.List;
  35 
  36 import java.beans.JavaBean;
  37 import java.beans.BeanProperty;
  38 import java.beans.PropertyChangeEvent;
  39 import java.beans.PropertyChangeListener;
  40 import java.beans.Transient;
  41 
  42 import javax.swing.event.*;
  43 import javax.accessibility.*;
  44 import javax.swing.plaf.*;
  45 import javax.swing.text.Position;
  46 
  47 import java.io.ObjectOutputStream;
  48 import java.io.IOException;
  49 import java.io.Serializable;
  50 
  51 import sun.awt.AWTAccessor;
  52 import sun.awt.AWTAccessor.MouseEventAccessor;
  53 import sun.swing.SwingUtilities2;
  54 import sun.swing.SwingUtilities2.Section;
  55 import static sun.swing.SwingUtilities2.Section.*;
  56 
  57 /**
  58  * A component that displays a list of objects and allows the user to select
  59  * one or more items. A separate model, {@code ListModel}, maintains the
  60  * contents of the list.
  61  * <p>
  62  * It's easy to display an array or Vector of objects, using the {@code JList}
  63  * constructor that automatically builds a read-only {@code ListModel} instance
  64  * for you:
  65  * <pre>
  66  * {@code
  67  * // Create a JList that displays strings from an array
  68  *
  69  * String[] data = {"one", "two", "three", "four"};
  70  * JList<String> myList = new JList<String>(data);
  71  *
  72  * // Create a JList that displays the superclasses of JList.class, by
  73  * // creating it with a Vector populated with this data
  74  *
  75  * Vector<Class<?>> superClasses = new Vector<Class<?>>();
  76  * Class<JList> rootClass = javax.swing.JList.class;
  77  * for(Class<?> cls = rootClass; cls != null; cls = cls.getSuperclass()) {
  78  *     superClasses.addElement(cls);
  79  * }
  80  * JList<Class<?>> myList = new JList<Class<?>>(superClasses);
  81  *
  82  * // The automatically created model is stored in JList's "model"
  83  * // property, which you can retrieve
  84  *
  85  * ListModel<Class<?>> model = myList.getModel();
  86  * for(int i = 0; i < model.getSize(); i++) {
  87  *     System.out.println(model.getElementAt(i));
  88  * }
  89  * }
  90  * </pre>
  91  * <p>
  92  * A {@code ListModel} can be supplied directly to a {@code JList} by way of a
  93  * constructor or the {@code setModel} method. The contents need not be static -
  94  * the number of items, and the values of items can change over time. A correct
  95  * {@code ListModel} implementation notifies the set of
  96  * {@code javax.swing.event.ListDataListener}s that have been added to it, each
  97  * time a change occurs. These changes are characterized by a
  98  * {@code javax.swing.event.ListDataEvent}, which identifies the range of list
  99  * indices that have been modified, added, or removed. {@code JList}'s
 100  * {@code ListUI} is responsible for keeping the visual representation up to
 101  * date with changes, by listening to the model.
 102  * <p>
 103  * Simple, dynamic-content, {@code JList} applications can use the
 104  * {@code DefaultListModel} class to maintain list elements. This class
 105  * implements the {@code ListModel} interface and also provides a
 106  * <code>java.util.Vector</code>-like API. Applications that need a more
 107  * custom <code>ListModel</code> implementation may instead wish to subclass
 108  * {@code AbstractListModel}, which provides basic support for managing and
 109  * notifying listeners. For example, a read-only implementation of
 110  * {@code AbstractListModel}:
 111  * <pre>
 112  * {@code
 113  * // This list model has about 2^16 elements.  Enjoy scrolling.
 114  *
 115  * ListModel<String> bigData = new AbstractListModel<String>() {
 116  *     public int getSize() { return Short.MAX_VALUE; }
 117  *     public String getElementAt(int index) { return "Index " + index; }
 118  * };
 119  * }
 120  * </pre>
 121  * <p>
 122  * The selection state of a {@code JList} is managed by another separate
 123  * model, an instance of {@code ListSelectionModel}. {@code JList} is
 124  * initialized with a selection model on construction, and also contains
 125  * methods to query or set this selection model. Additionally, {@code JList}
 126  * provides convenient methods for easily managing the selection. These methods,
 127  * such as {@code setSelectedIndex} and {@code getSelectedValue}, are cover
 128  * methods that take care of the details of interacting with the selection
 129  * model. By default, {@code JList}'s selection model is configured to allow any
 130  * combination of items to be selected at a time; selection mode
 131  * {@code MULTIPLE_INTERVAL_SELECTION}. The selection mode can be changed
 132  * on the selection model directly, or via {@code JList}'s cover method.
 133  * Responsibility for updating the selection model in response to user gestures
 134  * lies with the list's {@code ListUI}.
 135  * <p>
 136  * A correct {@code ListSelectionModel} implementation notifies the set of
 137  * {@code javax.swing.event.ListSelectionListener}s that have been added to it
 138  * each time a change to the selection occurs. These changes are characterized
 139  * by a {@code javax.swing.event.ListSelectionEvent}, which identifies the range
 140  * of the selection change.
 141  * <p>
 142  * The preferred way to listen for changes in list selection is to add
 143  * {@code ListSelectionListener}s directly to the {@code JList}. {@code JList}
 144  * then takes care of listening to the selection model and notifying your
 145  * listeners of change.
 146  * <p>
 147  * Responsibility for listening to selection changes in order to keep the list's
 148  * visual representation up to date lies with the list's {@code ListUI}.
 149  * <p>
 150  * <a id="renderer"></a>
 151  * Painting of cells in a {@code JList} is handled by a delegate called a
 152  * cell renderer, installed on the list as the {@code cellRenderer} property.
 153  * The renderer provides a {@code java.awt.Component} that is used
 154  * like a "rubber stamp" to paint the cells. Each time a cell needs to be
 155  * painted, the list's {@code ListUI} asks the cell renderer for the component,
 156  * moves it into place, and has it paint the contents of the cell by way of its
 157  * {@code paint} method. A default cell renderer, which uses a {@code JLabel}
 158  * component to render, is installed by the lists's {@code ListUI}. You can
 159  * substitute your own renderer using code like this:
 160  * <pre>
 161  * {@code
 162  *  // Display an icon and a string for each object in the list.
 163  *
 164  * class MyCellRenderer extends JLabel implements ListCellRenderer<Object> {
 165  *     static final ImageIcon longIcon = new ImageIcon("long.gif");
 166  *     static final ImageIcon shortIcon = new ImageIcon("short.gif");
 167  *
 168  *     // This is the only method defined by ListCellRenderer.
 169  *     // We just reconfigure the JLabel each time we're called.
 170  *
 171  *     public Component getListCellRendererComponent(
 172  *       JList<?> list,           // the list
 173  *       Object value,            // value to display
 174  *       int index,               // cell index
 175  *       boolean isSelected,      // is the cell selected
 176  *       boolean cellHasFocus)    // does the cell have focus
 177  *     {
 178  *         String s = value.toString();
 179  *         setText(s);
 180  *         setIcon((s.length() > 10) ? longIcon : shortIcon);
 181  *         if (isSelected) {
 182  *             setBackground(list.getSelectionBackground());
 183  *             setForeground(list.getSelectionForeground());
 184  *         } else {
 185  *             setBackground(list.getBackground());
 186  *             setForeground(list.getForeground());
 187  *         }
 188  *         setEnabled(list.isEnabled());
 189  *         setFont(list.getFont());
 190  *         setOpaque(true);
 191  *         return this;
 192  *     }
 193  * }
 194  *
 195  * myList.setCellRenderer(new MyCellRenderer());
 196  * }
 197  * </pre>
 198  * <p>
 199  * Another job for the cell renderer is in helping to determine sizing
 200  * information for the list. By default, the list's {@code ListUI} determines
 201  * the size of cells by asking the cell renderer for its preferred
 202  * size for each list item. This can be expensive for large lists of items.
 203  * To avoid these calculations, you can set a {@code fixedCellWidth} and
 204  * {@code fixedCellHeight} on the list, or have these values calculated
 205  * automatically based on a single prototype value:
 206  * <a id="prototype_example"></a>
 207  * <pre>
 208  * {@code
 209  * JList<String> bigDataList = new JList<String>(bigData);
 210  *
 211  * // We don't want the JList implementation to compute the width
 212  * // or height of all of the list cells, so we give it a string
 213  * // that's as big as we'll need for any cell.  It uses this to
 214  * // compute values for the fixedCellWidth and fixedCellHeight
 215  * // properties.
 216  *
 217  * bigDataList.setPrototypeCellValue("Index 1234567890");
 218  * }
 219  * </pre>
 220  * <p>
 221  * {@code JList} doesn't implement scrolling directly. To create a list that
 222  * scrolls, make it the viewport view of a {@code JScrollPane}. For example:
 223  * <pre>
 224  * JScrollPane scrollPane = new JScrollPane(myList);
 225  *
 226  * // Or in two steps:
 227  * JScrollPane scrollPane = new JScrollPane();
 228  * scrollPane.getViewport().setView(myList);
 229  * </pre>
 230  * <p>
 231  * {@code JList} doesn't provide any special handling of double or triple
 232  * (or N) mouse clicks, but it's easy to add a {@code MouseListener} if you
 233  * wish to take action on these events. Use the {@code locationToIndex}
 234  * method to determine what cell was clicked. For example:
 235  * <pre>
 236  * MouseListener mouseListener = new MouseAdapter() {
 237  *     public void mouseClicked(MouseEvent e) {
 238  *         if (e.getClickCount() == 2) {
 239  *             int index = list.locationToIndex(e.getPoint());
 240  *             System.out.println("Double clicked on Item " + index);
 241  *          }
 242  *     }
 243  * };
 244  * list.addMouseListener(mouseListener);
 245  * </pre>
 246  * <p>
 247  * <strong>Warning:</strong> Swing is not thread safe. For more
 248  * information see <a
 249  * href="package-summary.html#threading">Swing's Threading
 250  * Policy</a>.
 251  * <p>
 252  * <strong>Warning:</strong>
 253  * Serialized objects of this class will not be compatible with
 254  * future Swing releases. The current serialization support is
 255  * appropriate for short term storage or RMI between applications running
 256  * the same version of Swing.  As of 1.4, support for long term storage
 257  * of all JavaBeans&trade;
 258  * has been added to the <code>java.beans</code> package.
 259  * Please see {@link java.beans.XMLEncoder}.
 260  * <p>
 261  * See <a href="http://docs.oracle.com/javase/tutorial/uiswing/components/list.html">How to Use Lists</a>
 262  * in <a href="http://docs.oracle.com/javase/tutorial/"><em>The Java Tutorial</em></a>
 263  * for further documentation.
 264  *
 265  * @see ListModel
 266  * @see AbstractListModel
 267  * @see DefaultListModel
 268  * @see ListSelectionModel
 269  * @see DefaultListSelectionModel
 270  * @see ListCellRenderer
 271  * @see DefaultListCellRenderer
 272  *
 273  * @param <E> the type of the elements of this list
 274  *
 275  * @author Hans Muller
 276  * @since 1.2
 277  */
 278 @JavaBean(defaultProperty = "UI", description = "A component which allows for the selection of one or more objects from a list.")
 279 @SwingContainer(false)
 280 @SuppressWarnings("serial") // Same-version serialization only
 281 public class JList<E> extends JComponent implements Scrollable, Accessible
 282 {
 283     /**
 284      * @see #getUIClassID
 285      * @see #readObject
 286      */
 287     private static final String uiClassID = "ListUI";
 288 
 289     /**
 290      * Indicates a vertical layout of cells, in a single column;
 291      * the default layout.
 292      * @see #setLayoutOrientation
 293      * @since 1.4
 294      */
 295     public static final int VERTICAL = 0;
 296 
 297     /**
 298      * Indicates a "newspaper style" layout with cells flowing vertically
 299      * then horizontally.
 300      * @see #setLayoutOrientation
 301      * @since 1.4
 302      */
 303     public static final int VERTICAL_WRAP = 1;
 304 
 305     /**
 306      * Indicates a "newspaper style" layout with cells flowing horizontally
 307      * then vertically.
 308      * @see #setLayoutOrientation
 309      * @since 1.4
 310      */
 311     public static final int HORIZONTAL_WRAP = 2;
 312 
 313     private int fixedCellWidth = -1;
 314     private int fixedCellHeight = -1;
 315     private int horizontalScrollIncrement = -1;
 316     private E prototypeCellValue;
 317     private int visibleRowCount = 8;
 318     private Color selectionForeground;
 319     private Color selectionBackground;
 320     private boolean dragEnabled;
 321 
 322     private ListSelectionModel selectionModel;
 323     private ListModel<E> dataModel;
 324     private ListCellRenderer<? super E> cellRenderer;
 325     private ListSelectionListener selectionListener;
 326 
 327     /**
 328      * How to lay out the cells; defaults to <code>VERTICAL</code>.
 329      */
 330     private int layoutOrientation;
 331 
 332     /**
 333      * The drop mode for this component.
 334      */
 335     private DropMode dropMode = DropMode.USE_SELECTION;
 336 
 337     /**
 338      * The drop location.
 339      */
 340     private transient DropLocation dropLocation;
 341 
 342     /**
 343      * Flag to indicate UI update is in progress
 344      */
 345     private transient boolean updateInProgress;
 346 
 347     /**
 348      * A subclass of <code>TransferHandler.DropLocation</code> representing
 349      * a drop location for a <code>JList</code>.
 350      *
 351      * @see #getDropLocation
 352      * @since 1.6
 353      */
 354     public static final class DropLocation extends TransferHandler.DropLocation {
 355         private final int index;
 356         private final boolean isInsert;
 357 
 358         private DropLocation(Point p, int index, boolean isInsert) {
 359             super(p);
 360             this.index = index;
 361             this.isInsert = isInsert;
 362         }
 363 
 364         /**
 365          * Returns the index where dropped data should be placed in the
 366          * list. Interpretation of the value depends on the drop mode set on
 367          * the associated component. If the drop mode is either
 368          * <code>DropMode.USE_SELECTION</code> or <code>DropMode.ON</code>,
 369          * the return value is an index of a row in the list. If the drop mode is
 370          * <code>DropMode.INSERT</code>, the return value refers to the index
 371          * where the data should be inserted. If the drop mode is
 372          * <code>DropMode.ON_OR_INSERT</code>, the value of
 373          * <code>isInsert()</code> indicates whether the index is an index
 374          * of a row, or an insert index.
 375          * <p>
 376          * <code>-1</code> indicates that the drop occurred over empty space,
 377          * and no index could be calculated.
 378          *
 379          * @return the drop index
 380          */
 381         public int getIndex() {
 382             return index;
 383         }
 384 
 385         /**
 386          * Returns whether or not this location represents an insert
 387          * location.
 388          *
 389          * @return whether or not this is an insert location
 390          */
 391         public boolean isInsert() {
 392             return isInsert;
 393         }
 394 
 395         /**
 396          * Returns a string representation of this drop location.
 397          * This method is intended to be used for debugging purposes,
 398          * and the content and format of the returned string may vary
 399          * between implementations.
 400          *
 401          * @return a string representation of this drop location
 402          */
 403         public String toString() {
 404             return getClass().getName()
 405                    + "[dropPoint=" + getDropPoint() + ","
 406                    + "index=" + index + ","
 407                    + "insert=" + isInsert + "]";
 408         }
 409     }
 410 
 411     /**
 412      * Constructs a {@code JList} that displays elements from the specified,
 413      * {@code non-null}, model. All {@code JList} constructors delegate to
 414      * this one.
 415      * <p>
 416      * This constructor registers the list with the {@code ToolTipManager},
 417      * allowing for tooltips to be provided by the cell renderers.
 418      *
 419      * @param dataModel the model for the list
 420      * @exception IllegalArgumentException if the model is {@code null}
 421      */
 422     public JList(ListModel<E> dataModel)
 423     {
 424         if (dataModel == null) {
 425             throw new IllegalArgumentException("dataModel must be non null");
 426         }
 427 
 428         // Register with the ToolTipManager so that tooltips from the
 429         // renderer show through.
 430         ToolTipManager toolTipManager = ToolTipManager.sharedInstance();
 431         toolTipManager.registerComponent(this);
 432 
 433         layoutOrientation = VERTICAL;
 434 
 435         this.dataModel = dataModel;
 436         selectionModel = createSelectionModel();
 437         setAutoscrolls(true);
 438         setOpaque(true);
 439         updateUI();
 440     }
 441 
 442 
 443     /**
 444      * Constructs a <code>JList</code> that displays the elements in
 445      * the specified array. This constructor creates a read-only model
 446      * for the given array, and then delegates to the constructor that
 447      * takes a {@code ListModel}.
 448      * <p>
 449      * Attempts to pass a {@code null} value to this method results in
 450      * undefined behavior and, most likely, exceptions. The created model
 451      * references the given array directly. Attempts to modify the array
 452      * after constructing the list results in undefined behavior.
 453      *
 454      * @param  listData  the array of Objects to be loaded into the data model,
 455      *                   {@code non-null}
 456      */
 457     public JList(final E[] listData)
 458     {
 459         this (
 460             new AbstractListModel<E>() {
 461                 public int getSize() { return listData.length; }
 462                 public E getElementAt(int i) { return listData[i]; }
 463             }
 464         );
 465     }
 466 
 467 
 468     /**
 469      * Constructs a <code>JList</code> that displays the elements in
 470      * the specified <code>Vector</code>. This constructor creates a read-only
 471      * model for the given {@code Vector}, and then delegates to the constructor
 472      * that takes a {@code ListModel}.
 473      * <p>
 474      * Attempts to pass a {@code null} value to this method results in
 475      * undefined behavior and, most likely, exceptions. The created model
 476      * references the given {@code Vector} directly. Attempts to modify the
 477      * {@code Vector} after constructing the list results in undefined behavior.
 478      *
 479      * @param  listData  the <code>Vector</code> to be loaded into the
 480      *                   data model, {@code non-null}
 481      */
 482     public JList(final Vector<? extends E> listData) {
 483         this (
 484             new AbstractListModel<E>() {
 485                 public int getSize() { return listData.size(); }
 486                 public E getElementAt(int i) { return listData.elementAt(i); }
 487             }
 488         );
 489     }
 490 
 491 
 492     /**
 493      * Constructs a <code>JList</code> with an empty, read-only, model.
 494      */
 495     public JList() {
 496         this (
 497             new AbstractListModel<E>() {
 498               public int getSize() { return 0; }
 499               public E getElementAt(int i) { throw new IndexOutOfBoundsException("No Data Model"); }
 500             }
 501         );
 502     }
 503 
 504 
 505     /**
 506      * Returns the {@code ListUI}, the look and feel object that
 507      * renders this component.
 508      *
 509      * @return the <code>ListUI</code> object that renders this component
 510      */
 511     public ListUI getUI() {
 512         return (ListUI)ui;
 513     }
 514 
 515 
 516     /**
 517      * Sets the {@code ListUI}, the look and feel object that
 518      * renders this component.
 519      *
 520      * @param ui  the <code>ListUI</code> object
 521      * @see UIDefaults#getUI
 522      */
 523     @BeanProperty(hidden = true, visualUpdate = true, description
 524             = "The UI object that implements the Component's LookAndFeel.")
 525     public void setUI(ListUI ui) {
 526         super.setUI(ui);
 527     }
 528 
 529 
 530     /**
 531      * Resets the {@code ListUI} property by setting it to the value provided
 532      * by the current look and feel. If the current cell renderer was installed
 533      * by the developer (rather than the look and feel itself), this also causes
 534      * the cell renderer and its children to be updated, by calling
 535      * {@code SwingUtilities.updateComponentTreeUI} on it.
 536      *
 537      * @see UIManager#getUI
 538      * @see SwingUtilities#updateComponentTreeUI
 539      */
 540     public void updateUI() {
 541         if (!updateInProgress) {
 542             updateInProgress = true;
 543             try {
 544                 setUI((ListUI)UIManager.getUI(this));
 545 
 546                 ListCellRenderer<? super E> renderer = getCellRenderer();
 547                 if (renderer instanceof Component) {
 548                     SwingUtilities.updateComponentTreeUI((Component)renderer);
 549                 }
 550             } finally {
 551                 updateInProgress = false;
 552             }
 553         }
 554     }
 555 
 556 
 557     /**
 558      * Returns {@code "ListUI"}, the <code>UIDefaults</code> key used to look
 559      * up the name of the {@code javax.swing.plaf.ListUI} class that defines
 560      * the look and feel for this component.
 561      *
 562      * @return the string "ListUI"
 563      * @see JComponent#getUIClassID
 564      * @see UIDefaults#getUI
 565      */
 566     @BeanProperty(bound = false)
 567     public String getUIClassID() {
 568         return uiClassID;
 569     }
 570 
 571 
 572     /* -----private-----
 573      * This method is called by setPrototypeCellValue and setCellRenderer
 574      * to update the fixedCellWidth and fixedCellHeight properties from the
 575      * current value of prototypeCellValue (if it's non null).
 576      * <p>
 577      * This method sets fixedCellWidth and fixedCellHeight but does <b>not</b>
 578      * generate PropertyChangeEvents for them.
 579      *
 580      * @see #setPrototypeCellValue
 581      * @see #setCellRenderer
 582      */
 583     private void updateFixedCellSize()
 584     {
 585         ListCellRenderer<? super E> cr = getCellRenderer();
 586         E value = getPrototypeCellValue();
 587 
 588         if ((cr != null) && (value != null)) {
 589             Component c = cr.getListCellRendererComponent(this, value, 0, false, false);
 590 
 591             /* The ListUI implementation will add Component c to its private
 592              * CellRendererPane however we can't assume that's already
 593              * been done here.  So we temporarily set the one "inherited"
 594              * property that may affect the renderer components preferred size:
 595              * its font.
 596              */
 597             Font f = c.getFont();
 598             c.setFont(getFont());
 599 
 600             Dimension d = c.getPreferredSize();
 601             fixedCellWidth = d.width;
 602             fixedCellHeight = d.height;
 603 
 604             c.setFont(f);
 605         }
 606     }
 607 
 608 
 609     /**
 610      * Returns the "prototypical" cell value -- a value used to calculate a
 611      * fixed width and height for cells. This can be {@code null} if there
 612      * is no such value.
 613      *
 614      * @return the value of the {@code prototypeCellValue} property
 615      * @see #setPrototypeCellValue
 616      */
 617     public E getPrototypeCellValue() {
 618         return prototypeCellValue;
 619     }
 620 
 621     /**
 622      * Sets the {@code prototypeCellValue} property, and then (if the new value
 623      * is {@code non-null}), computes the {@code fixedCellWidth} and
 624      * {@code fixedCellHeight} properties by requesting the cell renderer
 625      * component for the given value (and index 0) from the cell renderer, and
 626      * using that component's preferred size.
 627      * <p>
 628      * This method is useful when the list is too long to allow the
 629      * {@code ListUI} to compute the width/height of each cell, and there is a
 630      * single cell value that is known to occupy as much space as any of the
 631      * others, a so-called prototype.
 632      * <p>
 633      * While all three of the {@code prototypeCellValue},
 634      * {@code fixedCellHeight}, and {@code fixedCellWidth} properties may be
 635      * modified by this method, {@code PropertyChangeEvent} notifications are
 636      * only sent when the {@code prototypeCellValue} property changes.
 637      * <p>
 638      * To see an example which sets this property, see the
 639      * <a href="#prototype_example">class description</a> above.
 640      * <p>
 641      * The default value of this property is <code>null</code>.
 642      * <p>
 643      * This is a JavaBeans bound property.
 644      *
 645      * @param prototypeCellValue  the value on which to base
 646      *                          <code>fixedCellWidth</code> and
 647      *                          <code>fixedCellHeight</code>
 648      * @see #getPrototypeCellValue
 649      * @see #setFixedCellWidth
 650      * @see #setFixedCellHeight
 651      * @see JComponent#addPropertyChangeListener
 652      */
 653     @BeanProperty(visualUpdate = true, description
 654             = "The cell prototype value, used to compute cell width and height.")
 655     public void setPrototypeCellValue(E prototypeCellValue) {
 656         E oldValue = this.prototypeCellValue;
 657         this.prototypeCellValue = prototypeCellValue;
 658 
 659         /* If the prototypeCellValue has changed and is non-null,
 660          * then recompute fixedCellWidth and fixedCellHeight.
 661          */
 662 
 663         if ((prototypeCellValue != null) && !prototypeCellValue.equals(oldValue)) {
 664             updateFixedCellSize();
 665         }
 666 
 667         firePropertyChange("prototypeCellValue", oldValue, prototypeCellValue);
 668     }
 669 
 670 
 671     /**
 672      * Returns the value of the {@code fixedCellWidth} property.
 673      *
 674      * @return the fixed cell width
 675      * @see #setFixedCellWidth
 676      */
 677     public int getFixedCellWidth() {
 678         return fixedCellWidth;
 679     }
 680 
 681     /**
 682      * Sets a fixed value to be used for the width of every cell in the list.
 683      * If {@code width} is -1, cell widths are computed in the {@code ListUI}
 684      * by applying <code>getPreferredSize</code> to the cell renderer component
 685      * for each list element.
 686      * <p>
 687      * The default value of this property is {@code -1}.
 688      * <p>
 689      * This is a JavaBeans bound property.
 690      *
 691      * @param width the width to be used for all cells in the list
 692      * @see #setPrototypeCellValue
 693      * @see #setFixedCellWidth
 694      * @see JComponent#addPropertyChangeListener
 695      */
 696     @BeanProperty(visualUpdate = true, description
 697             = "Defines a fixed cell width when greater than zero.")
 698     public void setFixedCellWidth(int width) {
 699         int oldValue = fixedCellWidth;
 700         fixedCellWidth = width;
 701         firePropertyChange("fixedCellWidth", oldValue, fixedCellWidth);
 702     }
 703 
 704 
 705     /**
 706      * Returns the value of the {@code fixedCellHeight} property.
 707      *
 708      * @return the fixed cell height
 709      * @see #setFixedCellHeight
 710      */
 711     public int getFixedCellHeight() {
 712         return fixedCellHeight;
 713     }
 714 
 715     /**
 716      * Sets a fixed value to be used for the height of every cell in the list.
 717      * If {@code height} is -1, cell heights are computed in the {@code ListUI}
 718      * by applying <code>getPreferredSize</code> to the cell renderer component
 719      * for each list element.
 720      * <p>
 721      * The default value of this property is {@code -1}.
 722      * <p>
 723      * This is a JavaBeans bound property.
 724      *
 725      * @param height the height to be used for all cells in the list
 726      * @see #setPrototypeCellValue
 727      * @see #setFixedCellWidth
 728      * @see JComponent#addPropertyChangeListener
 729      */
 730     @BeanProperty(visualUpdate = true, description
 731             = "Defines a fixed cell height when greater than zero.")
 732     public void setFixedCellHeight(int height) {
 733         int oldValue = fixedCellHeight;
 734         fixedCellHeight = height;
 735         firePropertyChange("fixedCellHeight", oldValue, fixedCellHeight);
 736     }
 737 
 738 
 739     /**
 740      * Returns the object responsible for painting list items.
 741      *
 742      * @return the value of the {@code cellRenderer} property
 743      * @see #setCellRenderer
 744      */
 745     @Transient
 746     public ListCellRenderer<? super E> getCellRenderer() {
 747         return cellRenderer;
 748     }
 749 
 750     /**
 751      * Sets the delegate that is used to paint each cell in the list.
 752      * The job of a cell renderer is discussed in detail in the
 753      * <a href="#renderer">class level documentation</a>.
 754      * <p>
 755      * If the {@code prototypeCellValue} property is {@code non-null},
 756      * setting the cell renderer also causes the {@code fixedCellWidth} and
 757      * {@code fixedCellHeight} properties to be re-calculated. Only one
 758      * <code>PropertyChangeEvent</code> is generated however -
 759      * for the <code>cellRenderer</code> property.
 760      * <p>
 761      * The default value of this property is provided by the {@code ListUI}
 762      * delegate, i.e. by the look and feel implementation.
 763      * <p>
 764      * This is a JavaBeans bound property.
 765      *
 766      * @param cellRenderer the <code>ListCellRenderer</code>
 767      *                          that paints list cells
 768      * @see #getCellRenderer
 769      */
 770     @BeanProperty(visualUpdate = true, description
 771             = "The component used to draw the cells.")
 772     public void setCellRenderer(ListCellRenderer<? super E> cellRenderer) {
 773         ListCellRenderer<? super E> oldValue = this.cellRenderer;
 774         this.cellRenderer = cellRenderer;
 775 
 776         /* If the cellRenderer has changed and prototypeCellValue
 777          * was set, then recompute fixedCellWidth and fixedCellHeight.
 778          */
 779         if ((cellRenderer != null) && !cellRenderer.equals(oldValue)) {
 780             updateFixedCellSize();
 781         }
 782 
 783         firePropertyChange("cellRenderer", oldValue, cellRenderer);
 784     }
 785 
 786 
 787     /**
 788      * Returns the color used to draw the foreground of selected items.
 789      * {@code DefaultListCellRenderer} uses this color to draw the foreground
 790      * of items in the selected state, as do the renderers installed by most
 791      * {@code ListUI} implementations.
 792      *
 793      * @return the color to draw the foreground of selected items
 794      * @see #setSelectionForeground
 795      * @see DefaultListCellRenderer
 796      */
 797     public Color getSelectionForeground() {
 798         return selectionForeground;
 799     }
 800 
 801 
 802     /**
 803      * Sets the color used to draw the foreground of selected items, which
 804      * cell renderers can use to render text and graphics.
 805      * {@code DefaultListCellRenderer} uses this color to draw the foreground
 806      * of items in the selected state, as do the renderers installed by most
 807      * {@code ListUI} implementations.
 808      * <p>
 809      * The default value of this property is defined by the look and feel
 810      * implementation.
 811      * <p>
 812      * This is a JavaBeans bound property.
 813      *
 814      * @param selectionForeground  the {@code Color} to use in the foreground
 815      *                             for selected list items
 816      * @see #getSelectionForeground
 817      * @see #setSelectionBackground
 818      * @see #setForeground
 819      * @see #setBackground
 820      * @see #setFont
 821      * @see DefaultListCellRenderer
 822      */
 823     @BeanProperty(visualUpdate = true, description
 824             = "The foreground color of selected cells.")
 825     public void setSelectionForeground(Color selectionForeground) {
 826         Color oldValue = this.selectionForeground;
 827         this.selectionForeground = selectionForeground;
 828         firePropertyChange("selectionForeground", oldValue, selectionForeground);
 829     }
 830 
 831 
 832     /**
 833      * Returns the color used to draw the background of selected items.
 834      * {@code DefaultListCellRenderer} uses this color to draw the background
 835      * of items in the selected state, as do the renderers installed by most
 836      * {@code ListUI} implementations.
 837      *
 838      * @return the color to draw the background of selected items
 839      * @see #setSelectionBackground
 840      * @see DefaultListCellRenderer
 841      */
 842     public Color getSelectionBackground() {
 843         return selectionBackground;
 844     }
 845 
 846 
 847     /**
 848      * Sets the color used to draw the background of selected items, which
 849      * cell renderers can use fill selected cells.
 850      * {@code DefaultListCellRenderer} uses this color to fill the background
 851      * of items in the selected state, as do the renderers installed by most
 852      * {@code ListUI} implementations.
 853      * <p>
 854      * The default value of this property is defined by the look
 855      * and feel implementation.
 856      * <p>
 857      * This is a JavaBeans bound property.
 858      *
 859      * @param selectionBackground  the {@code Color} to use for the
 860      *                             background of selected cells
 861      * @see #getSelectionBackground
 862      * @see #setSelectionForeground
 863      * @see #setForeground
 864      * @see #setBackground
 865      * @see #setFont
 866      * @see DefaultListCellRenderer
 867      */
 868     @BeanProperty(visualUpdate = true, description
 869             = "The background color of selected cells.")
 870     public void setSelectionBackground(Color selectionBackground) {
 871         Color oldValue = this.selectionBackground;
 872         this.selectionBackground = selectionBackground;
 873         firePropertyChange("selectionBackground", oldValue, selectionBackground);
 874     }
 875 
 876 
 877     /**
 878      * Returns the value of the {@code visibleRowCount} property. See the
 879      * documentation for {@link #setVisibleRowCount} for details on how to
 880      * interpret this value.
 881      *
 882      * @return the value of the {@code visibleRowCount} property.
 883      * @see #setVisibleRowCount
 884      */
 885     public int getVisibleRowCount() {
 886         return visibleRowCount;
 887     }
 888 
 889     /**
 890      * Sets the {@code visibleRowCount} property, which has different meanings
 891      * depending on the layout orientation: For a {@code VERTICAL} layout
 892      * orientation, this sets the preferred number of rows to display without
 893      * requiring scrolling; for other orientations, it affects the wrapping of
 894      * cells.
 895      * <p>
 896      * In {@code VERTICAL} orientation:<br>
 897      * Setting this property affects the return value of the
 898      * {@link #getPreferredScrollableViewportSize} method, which is used to
 899      * calculate the preferred size of an enclosing viewport. See that method's
 900      * documentation for more details.
 901      * <p>
 902      * In {@code HORIZONTAL_WRAP} and {@code VERTICAL_WRAP} orientations:<br>
 903      * This affects how cells are wrapped. See the documentation of
 904      * {@link #setLayoutOrientation} for more details.
 905      * <p>
 906      * The default value of this property is {@code 8}.
 907      * <p>
 908      * Calling this method with a negative value results in the property
 909      * being set to {@code 0}.
 910      * <p>
 911      * This is a JavaBeans bound property.
 912      *
 913      * @param visibleRowCount  an integer specifying the preferred number of
 914      *                         rows to display without requiring scrolling
 915      * @see #getVisibleRowCount
 916      * @see #getPreferredScrollableViewportSize
 917      * @see #setLayoutOrientation
 918      * @see JComponent#getVisibleRect
 919      * @see JViewport
 920      */
 921     @BeanProperty(visualUpdate = true, description
 922             = "The preferred number of rows to display without requiring scrolling")
 923     public void setVisibleRowCount(int visibleRowCount) {
 924         int oldValue = this.visibleRowCount;
 925         this.visibleRowCount = Math.max(0, visibleRowCount);
 926         firePropertyChange("visibleRowCount", oldValue, visibleRowCount);
 927     }
 928 
 929 
 930     /**
 931      * Returns the layout orientation property for the list: {@code VERTICAL}
 932      * if the layout is a single column of cells, {@code VERTICAL_WRAP} if the
 933      * layout is "newspaper style" with the content flowing vertically then
 934      * horizontally, or {@code HORIZONTAL_WRAP} if the layout is "newspaper
 935      * style" with the content flowing horizontally then vertically.
 936      *
 937      * @return the value of the {@code layoutOrientation} property
 938      * @see #setLayoutOrientation
 939      * @since 1.4
 940      */
 941     public int getLayoutOrientation() {
 942         return layoutOrientation;
 943     }
 944 
 945 
 946     /**
 947      * Defines the way list cells are layed out. Consider a {@code JList}
 948      * with five cells. Cells can be layed out in one of the following ways:
 949      *
 950      * <pre>
 951      * VERTICAL:          0
 952      *                    1
 953      *                    2
 954      *                    3
 955      *                    4
 956      *
 957      * HORIZONTAL_WRAP:   0  1  2
 958      *                    3  4
 959      *
 960      * VERTICAL_WRAP:     0  3
 961      *                    1  4
 962      *                    2
 963      * </pre>
 964      * <p>
 965      * A description of these layouts follows:
 966      *
 967      * <table class="striped">
 968      * <caption>Describes layouts VERTICAL,HORIZONTAL_WRAP, and VERTICAL_WRAP
 969      * </caption>
 970      * <thead>
 971      *   <tr>
 972      *     <th scope="col">Value
 973      *     <th scope="col">Description
 974      * </thead>
 975      * <tbody>
 976      *   <tr>
 977      *     <th scope="row">{@code VERTICAL}
 978      *     <td>Cells are layed out vertically in a single column.
 979      *   <tr>
 980      *     <th scope="row">{@code HORIZONTAL_WRAP}
 981      *     <td>Cells are layed out horizontally, wrapping to a new row as
 982      *     necessary. If the {@code visibleRowCount} property is less than or
 983      *     equal to zero, wrapping is determined by the width of the list;
 984      *     otherwise wrapping is done in such a way as to ensure
 985      *     {@code visibleRowCount} rows in the list.
 986      *   <tr>
 987      *     <th scope="row">{@code VERTICAL_WRAP}
 988      *     <td>Cells are layed out vertically, wrapping to a new column as
 989      *     necessary. If the {@code visibleRowCount} property is less than or
 990      *     equal to zero, wrapping is determined by the height of the list;
 991      *     otherwise wrapping is done at {@code visibleRowCount} rows.
 992      * </tbody>
 993      * </table>
 994      *
 995      * The default value of this property is <code>VERTICAL</code>.
 996      *
 997      * @param layoutOrientation the new layout orientation, one of:
 998      *        {@code VERTICAL}, {@code HORIZONTAL_WRAP} or {@code VERTICAL_WRAP}
 999      * @see #getLayoutOrientation
1000      * @see #setVisibleRowCount
1001      * @see #getScrollableTracksViewportHeight
1002      * @see #getScrollableTracksViewportWidth
1003      * @throws IllegalArgumentException if {@code layoutOrientation} isn't one of the
1004      *         allowable values
1005      * @since 1.4
1006      */
1007     @BeanProperty(visualUpdate = true, enumerationValues = {
1008             "JList.VERTICAL",
1009             "JList.HORIZONTAL_WRAP",
1010             "JList.VERTICAL_WRAP"}, description
1011             = "Defines the way list cells are layed out.")
1012     public void setLayoutOrientation(int layoutOrientation) {
1013         int oldValue = this.layoutOrientation;
1014         switch (layoutOrientation) {
1015         case VERTICAL:
1016         case VERTICAL_WRAP:
1017         case HORIZONTAL_WRAP:
1018             this.layoutOrientation = layoutOrientation;
1019             firePropertyChange("layoutOrientation", oldValue, layoutOrientation);
1020             break;
1021         default:
1022             throw new IllegalArgumentException("layoutOrientation must be one of: VERTICAL, HORIZONTAL_WRAP or VERTICAL_WRAP");
1023         }
1024     }
1025 
1026 
1027     /**
1028      * Returns the smallest list index that is currently visible.
1029      * In a left-to-right {@code componentOrientation}, the first visible
1030      * cell is found closest to the list's upper-left corner. In right-to-left
1031      * orientation, it is found closest to the upper-right corner.
1032      * If nothing is visible or the list is empty, {@code -1} is returned.
1033      * Note that the returned cell may only be partially visible.
1034      *
1035      * @return the index of the first visible cell
1036      * @see #getLastVisibleIndex
1037      * @see JComponent#getVisibleRect
1038      */
1039     @BeanProperty(bound = false)
1040     public int getFirstVisibleIndex() {
1041         Rectangle r = getVisibleRect();
1042         int first;
1043         if (this.getComponentOrientation().isLeftToRight()) {
1044             first = locationToIndex(r.getLocation());
1045         } else {
1046             first = locationToIndex(new Point((r.x + r.width) - 1, r.y));
1047         }
1048         if (first != -1) {
1049             Rectangle bounds = getCellBounds(first, first);
1050             if (bounds != null) {
1051                 SwingUtilities.computeIntersection(r.x, r.y, r.width, r.height, bounds);
1052                 if (bounds.width == 0 || bounds.height == 0) {
1053                     first = -1;
1054                 }
1055             }
1056         }
1057         return first;
1058     }
1059 
1060 
1061     /**
1062      * Returns the largest list index that is currently visible.
1063      * If nothing is visible or the list is empty, {@code -1} is returned.
1064      * Note that the returned cell may only be partially visible.
1065      *
1066      * @return the index of the last visible cell
1067      * @see #getFirstVisibleIndex
1068      * @see JComponent#getVisibleRect
1069      */
1070     @BeanProperty(bound = false)
1071     public int getLastVisibleIndex() {
1072         boolean leftToRight = this.getComponentOrientation().isLeftToRight();
1073         Rectangle r = getVisibleRect();
1074         Point lastPoint;
1075         if (leftToRight) {
1076             lastPoint = new Point((r.x + r.width) - 1, (r.y + r.height) - 1);
1077         } else {
1078             lastPoint = new Point(r.x, (r.y + r.height) - 1);
1079         }
1080         int location = locationToIndex(lastPoint);
1081 
1082         if (location != -1) {
1083             Rectangle bounds = getCellBounds(location, location);
1084 
1085             if (bounds != null) {
1086                 SwingUtilities.computeIntersection(r.x, r.y, r.width, r.height, bounds);
1087                 if (bounds.width == 0 || bounds.height == 0) {
1088                     // Try the top left(LTR) or top right(RTL) corner, and
1089                     // then go across checking each cell for HORIZONTAL_WRAP.
1090                     // Try the lower left corner, and then go across checking
1091                     // each cell for other list layout orientation.
1092                     boolean isHorizontalWrap =
1093                         (getLayoutOrientation() == HORIZONTAL_WRAP);
1094                     Point visibleLocation = isHorizontalWrap ?
1095                         new Point(lastPoint.x, r.y) :
1096                         new Point(r.x, lastPoint.y);
1097                     int last;
1098                     int visIndex = -1;
1099                     int lIndex = location;
1100                     location = -1;
1101 
1102                     do {
1103                         last = visIndex;
1104                         visIndex = locationToIndex(visibleLocation);
1105 
1106                         if (visIndex != -1) {
1107                             bounds = getCellBounds(visIndex, visIndex);
1108                             if (visIndex != lIndex && bounds != null &&
1109                                 bounds.contains(visibleLocation)) {
1110                                 location = visIndex;
1111                                 if (isHorizontalWrap) {
1112                                     visibleLocation.y = bounds.y + bounds.height;
1113                                     if (visibleLocation.y >= lastPoint.y) {
1114                                         // Past visible region, bail.
1115                                         last = visIndex;
1116                                     }
1117                                 }
1118                                 else {
1119                                     visibleLocation.x = bounds.x + bounds.width;
1120                                     if (visibleLocation.x >= lastPoint.x) {
1121                                         // Past visible region, bail.
1122                                         last = visIndex;
1123                                     }
1124                                 }
1125 
1126                             }
1127                             else {
1128                                 last = visIndex;
1129                             }
1130                         }
1131                     } while (visIndex != -1 && last != visIndex);
1132                 }
1133             }
1134         }
1135         return location;
1136     }
1137 
1138 
1139     /**
1140      * Scrolls the list within an enclosing viewport to make the specified
1141      * cell completely visible. This calls {@code scrollRectToVisible} with
1142      * the bounds of the specified cell. For this method to work, the
1143      * {@code JList} must be within a <code>JViewport</code>.
1144      * <p>
1145      * If the given index is outside the list's range of cells, this method
1146      * results in nothing.
1147      *
1148      * @param index  the index of the cell to make visible
1149      * @see JComponent#scrollRectToVisible
1150      * @see #getVisibleRect
1151      */
1152     public void ensureIndexIsVisible(int index) {
1153         Rectangle cellBounds = getCellBounds(index, index);
1154         if (cellBounds != null) {
1155             scrollRectToVisible(cellBounds);
1156         }
1157     }
1158 
1159     /**
1160      * Turns on or off automatic drag handling. In order to enable automatic
1161      * drag handling, this property should be set to {@code true}, and the
1162      * list's {@code TransferHandler} needs to be {@code non-null}.
1163      * The default value of the {@code dragEnabled} property is {@code false}.
1164      * <p>
1165      * The job of honoring this property, and recognizing a user drag gesture,
1166      * lies with the look and feel implementation, and in particular, the list's
1167      * {@code ListUI}. When automatic drag handling is enabled, most look and
1168      * feels (including those that subclass {@code BasicLookAndFeel}) begin a
1169      * drag and drop operation whenever the user presses the mouse button over
1170      * an item and then moves the mouse a few pixels. Setting this property to
1171      * {@code true} can therefore have a subtle effect on how selections behave.
1172      * <p>
1173      * If a look and feel is used that ignores this property, you can still
1174      * begin a drag and drop operation by calling {@code exportAsDrag} on the
1175      * list's {@code TransferHandler}.
1176      *
1177      * @param b whether or not to enable automatic drag handling
1178      * @exception HeadlessException if
1179      *            <code>b</code> is <code>true</code> and
1180      *            <code>GraphicsEnvironment.isHeadless()</code>
1181      *            returns <code>true</code>
1182      * @see java.awt.GraphicsEnvironment#isHeadless
1183      * @see #getDragEnabled
1184      * @see #setTransferHandler
1185      * @see TransferHandler
1186      * @since 1.4
1187      */
1188     @BeanProperty(bound = false, description
1189             = "determines whether automatic drag handling is enabled")
1190     public void setDragEnabled(boolean b) {
1191         if (b && GraphicsEnvironment.isHeadless()) {
1192             throw new HeadlessException();
1193         }
1194         dragEnabled = b;
1195     }
1196 
1197     /**
1198      * Returns whether or not automatic drag handling is enabled.
1199      *
1200      * @return the value of the {@code dragEnabled} property
1201      * @see #setDragEnabled
1202      * @since 1.4
1203      */
1204     public boolean getDragEnabled() {
1205         return dragEnabled;
1206     }
1207 
1208     /**
1209      * Sets the drop mode for this component. For backward compatibility,
1210      * the default for this property is <code>DropMode.USE_SELECTION</code>.
1211      * Usage of one of the other modes is recommended, however, for an
1212      * improved user experience. <code>DropMode.ON</code>, for instance,
1213      * offers similar behavior of showing items as selected, but does so without
1214      * affecting the actual selection in the list.
1215      * <p>
1216      * <code>JList</code> supports the following drop modes:
1217      * <ul>
1218      *    <li><code>DropMode.USE_SELECTION</code></li>
1219      *    <li><code>DropMode.ON</code></li>
1220      *    <li><code>DropMode.INSERT</code></li>
1221      *    <li><code>DropMode.ON_OR_INSERT</code></li>
1222      * </ul>
1223      * The drop mode is only meaningful if this component has a
1224      * <code>TransferHandler</code> that accepts drops.
1225      *
1226      * @param dropMode the drop mode to use
1227      * @throws IllegalArgumentException if the drop mode is unsupported
1228      *         or <code>null</code>
1229      * @see #getDropMode
1230      * @see #getDropLocation
1231      * @see #setTransferHandler
1232      * @see TransferHandler
1233      * @since 1.6
1234      */
1235     public final void setDropMode(DropMode dropMode) {
1236         if (dropMode != null) {
1237             switch (dropMode) {
1238                 case USE_SELECTION:
1239                 case ON:
1240                 case INSERT:
1241                 case ON_OR_INSERT:
1242                     this.dropMode = dropMode;
1243                     return;
1244             }
1245         }
1246 
1247         throw new IllegalArgumentException(dropMode + ": Unsupported drop mode for list");
1248     }
1249 
1250     /**
1251      * Returns the drop mode for this component.
1252      *
1253      * @return the drop mode for this component
1254      * @see #setDropMode
1255      * @since 1.6
1256      */
1257     public final DropMode getDropMode() {
1258         return dropMode;
1259     }
1260 
1261     /**
1262      * Calculates a drop location in this component, representing where a
1263      * drop at the given point should insert data.
1264      *
1265      * @param p the point to calculate a drop location for
1266      * @return the drop location, or <code>null</code>
1267      */
1268     DropLocation dropLocationForPoint(Point p) {
1269         DropLocation location = null;
1270         Rectangle rect = null;
1271 
1272         int index = locationToIndex(p);
1273         if (index != -1) {
1274             rect = getCellBounds(index, index);
1275         }
1276 
1277         switch(dropMode) {
1278             case USE_SELECTION:
1279             case ON:
1280                 location = new DropLocation(p,
1281                     (rect != null && rect.contains(p)) ? index : -1,
1282                     false);
1283 
1284                 break;
1285             case INSERT:
1286                 if (index == -1) {
1287                     location = new DropLocation(p, getModel().getSize(), true);
1288                     break;
1289                 }
1290 
1291                 if (layoutOrientation == HORIZONTAL_WRAP) {
1292                     boolean ltr = getComponentOrientation().isLeftToRight();
1293 
1294                     if (SwingUtilities2.liesInHorizontal(rect, p, ltr, false) == TRAILING) {
1295                         index++;
1296                     // special case for below all cells
1297                     } else if (index == getModel().getSize() - 1 && p.y >= rect.y + rect.height) {
1298                         index++;
1299                     }
1300                 } else {
1301                     if (SwingUtilities2.liesInVertical(rect, p, false) == TRAILING) {
1302                         index++;
1303                     }
1304                 }
1305 
1306                 location = new DropLocation(p, index, true);
1307 
1308                 break;
1309             case ON_OR_INSERT:
1310                 if (index == -1) {
1311                     location = new DropLocation(p, getModel().getSize(), true);
1312                     break;
1313                 }
1314 
1315                 boolean between = false;
1316 
1317                 if (layoutOrientation == HORIZONTAL_WRAP) {
1318                     boolean ltr = getComponentOrientation().isLeftToRight();
1319 
1320                     Section section = SwingUtilities2.liesInHorizontal(rect, p, ltr, true);
1321                     if (section == TRAILING) {
1322                         index++;
1323                         between = true;
1324                     // special case for below all cells
1325                     } else if (index == getModel().getSize() - 1 && p.y >= rect.y + rect.height) {
1326                         index++;
1327                         between = true;
1328                     } else if (section == LEADING) {
1329                         between = true;
1330                     }
1331                 } else {
1332                     Section section = SwingUtilities2.liesInVertical(rect, p, true);
1333                     if (section == LEADING) {
1334                         between = true;
1335                     } else if (section == TRAILING) {
1336                         index++;
1337                         between = true;
1338                     }
1339                 }
1340 
1341                 location = new DropLocation(p, index, between);
1342 
1343                 break;
1344             default:
1345                 assert false : "Unexpected drop mode";
1346         }
1347 
1348         return location;
1349     }
1350 
1351     /**
1352      * Called to set or clear the drop location during a DnD operation.
1353      * In some cases, the component may need to use it's internal selection
1354      * temporarily to indicate the drop location. To help facilitate this,
1355      * this method returns and accepts as a parameter a state object.
1356      * This state object can be used to store, and later restore, the selection
1357      * state. Whatever this method returns will be passed back to it in
1358      * future calls, as the state parameter. If it wants the DnD system to
1359      * continue storing the same state, it must pass it back every time.
1360      * Here's how this is used:
1361      * <p>
1362      * Let's say that on the first call to this method the component decides
1363      * to save some state (because it is about to use the selection to show
1364      * a drop index). It can return a state object to the caller encapsulating
1365      * any saved selection state. On a second call, let's say the drop location
1366      * is being changed to something else. The component doesn't need to
1367      * restore anything yet, so it simply passes back the same state object
1368      * to have the DnD system continue storing it. Finally, let's say this
1369      * method is messaged with <code>null</code>. This means DnD
1370      * is finished with this component for now, meaning it should restore
1371      * state. At this point, it can use the state parameter to restore
1372      * said state, and of course return <code>null</code> since there's
1373      * no longer anything to store.
1374      *
1375      * @param location the drop location (as calculated by
1376      *        <code>dropLocationForPoint</code>) or <code>null</code>
1377      *        if there's no longer a valid drop location
1378      * @param state the state object saved earlier for this component,
1379      *        or <code>null</code>
1380      * @param forDrop whether or not the method is being called because an
1381      *        actual drop occurred
1382      * @return any saved state for this component, or <code>null</code> if none
1383      */
1384     Object setDropLocation(TransferHandler.DropLocation location,
1385                            Object state,
1386                            boolean forDrop) {
1387 
1388         Object retVal = null;
1389         DropLocation listLocation = (DropLocation)location;
1390 
1391         if (dropMode == DropMode.USE_SELECTION) {
1392             if (listLocation == null) {
1393                 if (!forDrop && state != null) {
1394                     setSelectedIndices(((int[][])state)[0]);
1395 
1396                     int anchor = ((int[][])state)[1][0];
1397                     int lead = ((int[][])state)[1][1];
1398 
1399                     SwingUtilities2.setLeadAnchorWithoutSelection(
1400                             getSelectionModel(), lead, anchor);
1401                 }
1402             } else {
1403                 if (dropLocation == null) {
1404                     int[] inds = getSelectedIndices();
1405                     retVal = new int[][] {inds, {getAnchorSelectionIndex(),
1406                                                  getLeadSelectionIndex()}};
1407                 } else {
1408                     retVal = state;
1409                 }
1410 
1411                 int index = listLocation.getIndex();
1412                 if (index == -1) {
1413                     clearSelection();
1414                     getSelectionModel().setAnchorSelectionIndex(-1);
1415                     getSelectionModel().setLeadSelectionIndex(-1);
1416                 } else {
1417                     setSelectionInterval(index, index);
1418                 }
1419             }
1420         }
1421 
1422         DropLocation old = dropLocation;
1423         dropLocation = listLocation;
1424         firePropertyChange("dropLocation", old, dropLocation);
1425 
1426         return retVal;
1427     }
1428 
1429     /**
1430      * Returns the location that this component should visually indicate
1431      * as the drop location during a DnD operation over the component,
1432      * or {@code null} if no location is to currently be shown.
1433      * <p>
1434      * This method is not meant for querying the drop location
1435      * from a {@code TransferHandler}, as the drop location is only
1436      * set after the {@code TransferHandler}'s <code>canImport</code>
1437      * has returned and has allowed for the location to be shown.
1438      * <p>
1439      * When this property changes, a property change event with
1440      * name "dropLocation" is fired by the component.
1441      * <p>
1442      * By default, responsibility for listening for changes to this property
1443      * and indicating the drop location visually lies with the list's
1444      * {@code ListUI}, which may paint it directly and/or install a cell
1445      * renderer to do so. Developers wishing to implement custom drop location
1446      * painting and/or replace the default cell renderer, may need to honor
1447      * this property.
1448      *
1449      * @return the drop location
1450      * @see #setDropMode
1451      * @see TransferHandler#canImport(TransferHandler.TransferSupport)
1452      * @since 1.6
1453      */
1454     @BeanProperty(bound = false)
1455     public final DropLocation getDropLocation() {
1456         return dropLocation;
1457     }
1458 
1459     /**
1460      * Returns the next list element whose {@code toString} value
1461      * starts with the given prefix.
1462      *
1463      * @param prefix the string to test for a match
1464      * @param startIndex the index for starting the search
1465      * @param bias the search direction, either
1466      * Position.Bias.Forward or Position.Bias.Backward.
1467      * @return the index of the next list element that
1468      * starts with the prefix; otherwise {@code -1}
1469      * @exception IllegalArgumentException if prefix is {@code null}
1470      * or startIndex is out of bounds
1471      * @since 1.4
1472      */
1473     public int getNextMatch(String prefix, int startIndex, Position.Bias bias) {
1474         ListModel<E> model = getModel();
1475         int max = model.getSize();
1476         if (prefix == null) {
1477             throw new IllegalArgumentException();
1478         }
1479         if (startIndex < 0 || startIndex >= max) {
1480             throw new IllegalArgumentException();
1481         }
1482         prefix = prefix.toUpperCase();
1483 
1484         // start search from the next element after the selected element
1485         int increment = (bias == Position.Bias.Forward) ? 1 : -1;
1486         int index = startIndex;
1487         do {
1488             E element = model.getElementAt(index);
1489 
1490             if (element != null) {
1491                 String string;
1492 
1493                 if (element instanceof String) {
1494                     string = ((String)element).toUpperCase();
1495                 }
1496                 else {
1497                     string = element.toString();
1498                     if (string != null) {
1499                         string = string.toUpperCase();
1500                     }
1501                 }
1502 
1503                 if (string != null && string.startsWith(prefix)) {
1504                     return index;
1505                 }
1506             }
1507             index = (index + increment + max) % max;
1508         } while (index != startIndex);
1509         return -1;
1510     }
1511 
1512     /**
1513      * Returns the tooltip text to be used for the given event. This overrides
1514      * {@code JComponent}'s {@code getToolTipText} to first check the cell
1515      * renderer component for the cell over which the event occurred, returning
1516      * its tooltip text, if any. This implementation allows you to specify
1517      * tooltip text on the cell level, by using {@code setToolTipText} on your
1518      * cell renderer component.
1519      * <p>
1520      * <strong>Note:</strong> For <code>JList</code> to properly display the
1521      * tooltips of its renderers in this manner, <code>JList</code> must be a
1522      * registered component with the <code>ToolTipManager</code>. This registration
1523      * is done automatically in the constructor. However, if at a later point
1524      * <code>JList</code> is unregistered, by way of a call to
1525      * {@code setToolTipText(null)}, tips from the renderers will no longer display.
1526      *
1527      * @param event the {@code MouseEvent} to fetch the tooltip text for
1528      * @see JComponent#setToolTipText
1529      * @see JComponent#getToolTipText
1530      */
1531     @SuppressWarnings("deprecation")
1532     public String getToolTipText(MouseEvent event) {
1533         if(event != null) {
1534             Point p = event.getPoint();
1535             int index = locationToIndex(p);
1536             ListCellRenderer<? super E> r = getCellRenderer();
1537             Rectangle cellBounds;
1538 
1539             if (index != -1 && r != null && (cellBounds =
1540                                getCellBounds(index, index)) != null &&
1541                                cellBounds.contains(p.x, p.y)) {
1542                 ListSelectionModel lsm = getSelectionModel();
1543                 Component rComponent = r.getListCellRendererComponent(
1544                            this, getModel().getElementAt(index), index,
1545                            lsm.isSelectedIndex(index),
1546                            (hasFocus() && (lsm.getLeadSelectionIndex() ==
1547                                            index)));
1548 
1549                 if(rComponent instanceof JComponent) {
1550                     MouseEvent      newEvent;
1551 
1552                     p.translate(-cellBounds.x, -cellBounds.y);
1553                     newEvent = new MouseEvent(rComponent, event.getID(),
1554                                               event.getWhen(),
1555                                               event.getModifiers(),
1556                                               p.x, p.y,
1557                                               event.getXOnScreen(),
1558                                               event.getYOnScreen(),
1559                                               event.getClickCount(),
1560                                               event.isPopupTrigger(),
1561                                               MouseEvent.NOBUTTON);
1562                     MouseEventAccessor meAccessor =
1563                         AWTAccessor.getMouseEventAccessor();
1564                     meAccessor.setCausedByTouchEvent(newEvent,
1565                         meAccessor.isCausedByTouchEvent(event));
1566 
1567                     String tip = ((JComponent)rComponent).getToolTipText(
1568                                               newEvent);
1569 
1570                     if (tip != null) {
1571                         return tip;
1572                     }
1573                 }
1574             }
1575         }
1576         return super.getToolTipText();
1577     }
1578 
1579     /**
1580      * --- ListUI Delegations ---
1581      */
1582 
1583 
1584     /**
1585      * Returns the cell index closest to the given location in the list's
1586      * coordinate system. To determine if the cell actually contains the
1587      * specified location, compare the point against the cell's bounds,
1588      * as provided by {@code getCellBounds}. This method returns {@code -1}
1589      * if the model is empty
1590      * <p>
1591      * This is a cover method that delegates to the method of the same name
1592      * in the list's {@code ListUI}. It returns {@code -1} if the list has
1593      * no {@code ListUI}.
1594      *
1595      * @param location the coordinates of the point
1596      * @return the cell index closest to the given location, or {@code -1}
1597      */
1598     public int locationToIndex(Point location) {
1599         ListUI ui = getUI();
1600         return (ui != null) ? ui.locationToIndex(this, location) : -1;
1601     }
1602 
1603 
1604     /**
1605      * Returns the origin of the specified item in the list's coordinate
1606      * system. This method returns {@code null} if the index isn't valid.
1607      * <p>
1608      * This is a cover method that delegates to the method of the same name
1609      * in the list's {@code ListUI}. It returns {@code null} if the list has
1610      * no {@code ListUI}.
1611      *
1612      * @param index the cell index
1613      * @return the origin of the cell, or {@code null}
1614      */
1615     public Point indexToLocation(int index) {
1616         ListUI ui = getUI();
1617         return (ui != null) ? ui.indexToLocation(this, index) : null;
1618     }
1619 
1620 
1621     /**
1622      * Returns the bounding rectangle, in the list's coordinate system,
1623      * for the range of cells specified by the two indices.
1624      * These indices can be supplied in any order.
1625      * <p>
1626      * If the smaller index is outside the list's range of cells, this method
1627      * returns {@code null}. If the smaller index is valid, but the larger
1628      * index is outside the list's range, the bounds of just the first index
1629      * is returned. Otherwise, the bounds of the valid range is returned.
1630      * <p>
1631      * This is a cover method that delegates to the method of the same name
1632      * in the list's {@code ListUI}. It returns {@code null} if the list has
1633      * no {@code ListUI}.
1634      *
1635      * @param index0 the first index in the range
1636      * @param index1 the second index in the range
1637      * @return the bounding rectangle for the range of cells, or {@code null}
1638      */
1639     public Rectangle getCellBounds(int index0, int index1) {
1640         ListUI ui = getUI();
1641         return (ui != null) ? ui.getCellBounds(this, index0, index1) : null;
1642     }
1643 
1644 
1645     /**
1646      * --- ListModel Support ---
1647      */
1648 
1649 
1650     /**
1651      * Returns the data model that holds the list of items displayed
1652      * by the <code>JList</code> component.
1653      *
1654      * @return the <code>ListModel</code> that provides the displayed
1655      *                          list of items
1656      * @see #setModel
1657      */
1658     public ListModel<E> getModel() {
1659         return dataModel;
1660     }
1661 
1662     /**
1663      * Sets the model that represents the contents or "value" of the
1664      * list, notifies property change listeners, and then clears the
1665      * list's selection.
1666      * <p>
1667      * This is a JavaBeans bound property.
1668      *
1669      * @param model  the <code>ListModel</code> that provides the
1670      *                                          list of items for display
1671      * @exception IllegalArgumentException  if <code>model</code> is
1672      *                                          <code>null</code>
1673      * @see #getModel
1674      * @see #clearSelection
1675      */
1676     @BeanProperty(visualUpdate = true, description
1677             = "The object that contains the data to be drawn by this JList.")
1678     public void setModel(ListModel<E> model) {
1679         if (model == null) {
1680             throw new IllegalArgumentException("model must be non null");
1681         }
1682         ListModel<E> oldValue = dataModel;
1683         dataModel = model;
1684         firePropertyChange("model", oldValue, dataModel);
1685         clearSelection();
1686     }
1687 
1688 
1689     /**
1690      * Constructs a read-only <code>ListModel</code> from an array of items,
1691      * and calls {@code setModel} with this model.
1692      * <p>
1693      * Attempts to pass a {@code null} value to this method results in
1694      * undefined behavior and, most likely, exceptions. The created model
1695      * references the given array directly. Attempts to modify the array
1696      * after invoking this method results in undefined behavior.
1697      *
1698      * @param listData an array of {@code E} containing the items to
1699      *        display in the list
1700      * @see #setModel
1701      */
1702     public void setListData(final E[] listData) {
1703         setModel (
1704             new AbstractListModel<E>() {
1705                 public int getSize() { return listData.length; }
1706                 public E getElementAt(int i) { return listData[i]; }
1707             }
1708         );
1709     }
1710 
1711 
1712     /**
1713      * Constructs a read-only <code>ListModel</code> from a <code>Vector</code>
1714      * and calls {@code setModel} with this model.
1715      * <p>
1716      * Attempts to pass a {@code null} value to this method results in
1717      * undefined behavior and, most likely, exceptions. The created model
1718      * references the given {@code Vector} directly. Attempts to modify the
1719      * {@code Vector} after invoking this method results in undefined behavior.
1720      *
1721      * @param listData a <code>Vector</code> containing the items to
1722      *                                          display in the list
1723      * @see #setModel
1724      */
1725     public void setListData(final Vector<? extends E> listData) {
1726         setModel (
1727             new AbstractListModel<E>() {
1728                 public int getSize() { return listData.size(); }
1729                 public E getElementAt(int i) { return listData.elementAt(i); }
1730             }
1731         );
1732     }
1733 
1734 
1735     /**
1736      * --- ListSelectionModel delegations and extensions ---
1737      */
1738 
1739 
1740     /**
1741      * Returns an instance of {@code DefaultListSelectionModel}; called
1742      * during construction to initialize the list's selection model
1743      * property.
1744      *
1745      * @return a {@code DefaultListSelecitonModel}, used to initialize
1746      *         the list's selection model property during construction
1747      * @see #setSelectionModel
1748      * @see DefaultListSelectionModel
1749      */
1750     protected ListSelectionModel createSelectionModel() {
1751         return new DefaultListSelectionModel();
1752     }
1753 
1754 
1755     /**
1756      * Returns the current selection model. The selection model maintains the
1757      * selection state of the list. See the class level documentation for more
1758      * details.
1759      *
1760      * @return the <code>ListSelectionModel</code> that maintains the
1761      *         list's selections
1762      *
1763      * @see #setSelectionModel
1764      * @see ListSelectionModel
1765      */
1766     public ListSelectionModel getSelectionModel() {
1767         return selectionModel;
1768     }
1769 
1770 
1771     /**
1772      * Notifies {@code ListSelectionListener}s added directly to the list
1773      * of selection changes made to the selection model. {@code JList}
1774      * listens for changes made to the selection in the selection model,
1775      * and forwards notification to listeners added to the list directly,
1776      * by calling this method.
1777      * <p>
1778      * This method constructs a {@code ListSelectionEvent} with this list
1779      * as the source, and the specified arguments, and sends it to the
1780      * registered {@code ListSelectionListeners}.
1781      *
1782      * @param firstIndex the first index in the range, {@code <= lastIndex}
1783      * @param lastIndex the last index in the range, {@code >= firstIndex}
1784      * @param isAdjusting whether or not this is one in a series of
1785      *        multiple events, where changes are still being made
1786      *
1787      * @see #addListSelectionListener
1788      * @see #removeListSelectionListener
1789      * @see javax.swing.event.ListSelectionEvent
1790      * @see EventListenerList
1791      */
1792     protected void fireSelectionValueChanged(int firstIndex, int lastIndex,
1793                                              boolean isAdjusting)
1794     {
1795         Object[] listeners = listenerList.getListenerList();
1796         ListSelectionEvent e = null;
1797 
1798         for (int i = listeners.length - 2; i >= 0; i -= 2) {
1799             if (listeners[i] == ListSelectionListener.class) {
1800                 if (e == null) {
1801                     e = new ListSelectionEvent(this, firstIndex, lastIndex,
1802                                                isAdjusting);
1803                 }
1804                 ((ListSelectionListener)listeners[i+1]).valueChanged(e);
1805             }
1806         }
1807     }
1808 
1809 
1810     /* A ListSelectionListener that forwards ListSelectionEvents from
1811      * the selectionModel to the JList ListSelectionListeners.  The
1812      * forwarded events only differ from the originals in that their
1813      * source is the JList instead of the selectionModel itself.
1814      */
1815     private class ListSelectionHandler implements ListSelectionListener, Serializable
1816     {
1817         public void valueChanged(ListSelectionEvent e) {
1818             fireSelectionValueChanged(e.getFirstIndex(),
1819                                       e.getLastIndex(),
1820                                       e.getValueIsAdjusting());
1821         }
1822     }
1823 
1824 
1825     /**
1826      * Adds a listener to the list, to be notified each time a change to the
1827      * selection occurs; the preferred way of listening for selection state
1828      * changes. {@code JList} takes care of listening for selection state
1829      * changes in the selection model, and notifies the given listener of
1830      * each change. {@code ListSelectionEvent}s sent to the listener have a
1831      * {@code source} property set to this list.
1832      *
1833      * @param listener the {@code ListSelectionListener} to add
1834      * @see #getSelectionModel
1835      * @see #getListSelectionListeners
1836      */
1837     public void addListSelectionListener(ListSelectionListener listener)
1838     {
1839         if (selectionListener == null) {
1840             selectionListener = new ListSelectionHandler();
1841             getSelectionModel().addListSelectionListener(selectionListener);
1842         }
1843 
1844         listenerList.add(ListSelectionListener.class, listener);
1845     }
1846 
1847 
1848     /**
1849      * Removes a selection listener from the list.
1850      *
1851      * @param listener the {@code ListSelectionListener} to remove
1852      * @see #addListSelectionListener
1853      * @see #getSelectionModel
1854      */
1855     public void removeListSelectionListener(ListSelectionListener listener) {
1856         listenerList.remove(ListSelectionListener.class, listener);
1857     }
1858 
1859 
1860     /**
1861      * Returns an array of all the {@code ListSelectionListener}s added
1862      * to this {@code JList} by way of {@code addListSelectionListener}.
1863      *
1864      * @return all of the {@code ListSelectionListener}s on this list, or
1865      *         an empty array if no listeners have been added
1866      * @see #addListSelectionListener
1867      * @since 1.4
1868      */
1869     @BeanProperty(bound = false)
1870     public ListSelectionListener[] getListSelectionListeners() {
1871         return listenerList.getListeners(ListSelectionListener.class);
1872     }
1873 
1874 
1875     /**
1876      * Sets the <code>selectionModel</code> for the list to a
1877      * non-<code>null</code> <code>ListSelectionModel</code>
1878      * implementation. The selection model handles the task of making single
1879      * selections, selections of contiguous ranges, and non-contiguous
1880      * selections.
1881      * <p>
1882      * This is a JavaBeans bound property.
1883      *
1884      * @param selectionModel  the <code>ListSelectionModel</code> that
1885      *                          implements the selections
1886      * @exception IllegalArgumentException   if <code>selectionModel</code>
1887      *                                          is <code>null</code>
1888      * @see #getSelectionModel
1889      */
1890     @BeanProperty(description
1891             = "The selection model, recording which cells are selected.")
1892     public void setSelectionModel(ListSelectionModel selectionModel) {
1893         if (selectionModel == null) {
1894             throw new IllegalArgumentException("selectionModel must be non null");
1895         }
1896 
1897         /* Remove the forwarding ListSelectionListener from the old
1898          * selectionModel, and add it to the new one, if necessary.
1899          */
1900         if (selectionListener != null) {
1901             this.selectionModel.removeListSelectionListener(selectionListener);
1902             selectionModel.addListSelectionListener(selectionListener);
1903         }
1904 
1905         ListSelectionModel oldValue = this.selectionModel;
1906         this.selectionModel = selectionModel;
1907         firePropertyChange("selectionModel", oldValue, selectionModel);
1908     }
1909 
1910 
1911     /**
1912      * Sets the selection mode for the list. This is a cover method that sets
1913      * the selection mode directly on the selection model.
1914      * <p>
1915      * The following list describes the accepted selection modes:
1916      * <ul>
1917      * <li>{@code ListSelectionModel.SINGLE_SELECTION} -
1918      *   Only one list index can be selected at a time. In this mode,
1919      *   {@code setSelectionInterval} and {@code addSelectionInterval} are
1920      *   equivalent, both replacing the current selection with the index
1921      *   represented by the second argument (the "lead").
1922      * <li>{@code ListSelectionModel.SINGLE_INTERVAL_SELECTION} -
1923      *   Only one contiguous interval can be selected at a time.
1924      *   In this mode, {@code addSelectionInterval} behaves like
1925      *   {@code setSelectionInterval} (replacing the current selection},
1926      *   unless the given interval is immediately adjacent to or overlaps
1927      *   the existing selection, and can be used to grow the selection.
1928      * <li>{@code ListSelectionModel.MULTIPLE_INTERVAL_SELECTION} -
1929      *   In this mode, there's no restriction on what can be selected.
1930      *   This mode is the default.
1931      * </ul>
1932      *
1933      * @param selectionMode the selection mode
1934      * @see #getSelectionMode
1935      * @throws IllegalArgumentException if the selection mode isn't
1936      *         one of those allowed
1937      */
1938     @BeanProperty(bound = false, enumerationValues = {
1939             "ListSelectionModel.SINGLE_SELECTION",
1940             "ListSelectionModel.SINGLE_INTERVAL_SELECTION",
1941             "ListSelectionModel.MULTIPLE_INTERVAL_SELECTION"}, description
1942             = "The selection mode.")
1943     public void setSelectionMode(int selectionMode) {
1944         getSelectionModel().setSelectionMode(selectionMode);
1945     }
1946 
1947     /**
1948      * Returns the current selection mode for the list. This is a cover
1949      * method that delegates to the method of the same name on the
1950      * list's selection model.
1951      *
1952      * @return the current selection mode
1953      * @see #setSelectionMode
1954      */
1955     public int getSelectionMode() {
1956         return getSelectionModel().getSelectionMode();
1957     }
1958 
1959 
1960     /**
1961      * Returns the anchor selection index. This is a cover method that
1962      * delegates to the method of the same name on the list's selection model.
1963      *
1964      * @return the anchor selection index
1965      * @see ListSelectionModel#getAnchorSelectionIndex
1966      */
1967     @BeanProperty(bound = false)
1968     public int getAnchorSelectionIndex() {
1969         return getSelectionModel().getAnchorSelectionIndex();
1970     }
1971 
1972 
1973     /**
1974      * Returns the lead selection index. This is a cover method that
1975      * delegates to the method of the same name on the list's selection model.
1976      *
1977      * @return the lead selection index
1978      * @see ListSelectionModel#getLeadSelectionIndex
1979      */
1980     @BeanProperty(bound = false, description
1981             = "The lead selection index.")
1982     public int getLeadSelectionIndex() {
1983         return getSelectionModel().getLeadSelectionIndex();
1984     }
1985 
1986 
1987     /**
1988      * Returns the smallest selected cell index, or {@code -1} if the selection
1989      * is empty. This is a cover method that delegates to the method of the same
1990      * name on the list's selection model.
1991      *
1992      * @return the smallest selected cell index, or {@code -1}
1993      * @see ListSelectionModel#getMinSelectionIndex
1994      */
1995     @BeanProperty(bound = false)
1996     public int getMinSelectionIndex() {
1997         return getSelectionModel().getMinSelectionIndex();
1998     }
1999 
2000 
2001     /**
2002      * Returns the largest selected cell index, or {@code -1} if the selection
2003      * is empty. This is a cover method that delegates to the method of the same
2004      * name on the list's selection model.
2005      *
2006      * @return the largest selected cell index
2007      * @see ListSelectionModel#getMaxSelectionIndex
2008      */
2009     @BeanProperty(bound = false)
2010     public int getMaxSelectionIndex() {
2011         return getSelectionModel().getMaxSelectionIndex();
2012     }
2013 
2014 
2015     /**
2016      * Returns {@code true} if the specified index is selected,
2017      * else {@code false}. This is a cover method that delegates to the method
2018      * of the same name on the list's selection model.
2019      *
2020      * @param index index to be queried for selection state
2021      * @return {@code true} if the specified index is selected,
2022      *         else {@code false}
2023      * @see ListSelectionModel#isSelectedIndex
2024      * @see #setSelectedIndex
2025      */
2026     public boolean isSelectedIndex(int index) {
2027         return getSelectionModel().isSelectedIndex(index);
2028     }
2029 
2030 
2031     /**
2032      * Returns {@code true} if nothing is selected, else {@code false}.
2033      * This is a cover method that delegates to the method of the same
2034      * name on the list's selection model.
2035      *
2036      * @return {@code true} if nothing is selected, else {@code false}
2037      * @see ListSelectionModel#isSelectionEmpty
2038      * @see #clearSelection
2039      */
2040     @BeanProperty(bound = false)
2041     public boolean isSelectionEmpty() {
2042         return getSelectionModel().isSelectionEmpty();
2043     }
2044 
2045 
2046     /**
2047      * Clears the selection; after calling this method, {@code isSelectionEmpty}
2048      * will return {@code true}. This is a cover method that delegates to the
2049      * method of the same name on the list's selection model.
2050      *
2051      * @see ListSelectionModel#clearSelection
2052      * @see #isSelectionEmpty
2053      */
2054     public void clearSelection() {
2055         getSelectionModel().clearSelection();
2056     }
2057 
2058 
2059     /**
2060      * Selects the specified interval. Both {@code anchor} and {@code lead}
2061      * indices are included. {@code anchor} doesn't have to be less than or
2062      * equal to {@code lead}. This is a cover method that delegates to the
2063      * method of the same name on the list's selection model.
2064      * <p>
2065      * Refer to the documentation of the selection model class being used
2066      * for details on how values less than {@code 0} are handled.
2067      *
2068      * @param anchor the first index to select
2069      * @param lead the last index to select
2070      * @see ListSelectionModel#setSelectionInterval
2071      * @see DefaultListSelectionModel#setSelectionInterval
2072      * @see #createSelectionModel
2073      * @see #addSelectionInterval
2074      * @see #removeSelectionInterval
2075      */
2076     public void setSelectionInterval(int anchor, int lead) {
2077         getSelectionModel().setSelectionInterval(anchor, lead);
2078     }
2079 
2080 
2081     /**
2082      * Sets the selection to be the union of the specified interval with current
2083      * selection. Both the {@code anchor} and {@code lead} indices are
2084      * included. {@code anchor} doesn't have to be less than or
2085      * equal to {@code lead}. This is a cover method that delegates to the
2086      * method of the same name on the list's selection model.
2087      * <p>
2088      * Refer to the documentation of the selection model class being used
2089      * for details on how values less than {@code 0} are handled.
2090      *
2091      * @param anchor the first index to add to the selection
2092      * @param lead the last index to add to the selection
2093      * @see ListSelectionModel#addSelectionInterval
2094      * @see DefaultListSelectionModel#addSelectionInterval
2095      * @see #createSelectionModel
2096      * @see #setSelectionInterval
2097      * @see #removeSelectionInterval
2098      */
2099     public void addSelectionInterval(int anchor, int lead) {
2100         getSelectionModel().addSelectionInterval(anchor, lead);
2101     }
2102 
2103 
2104     /**
2105      * Sets the selection to be the set difference of the specified interval
2106      * and the current selection. Both the {@code index0} and {@code index1}
2107      * indices are removed. {@code index0} doesn't have to be less than or
2108      * equal to {@code index1}. This is a cover method that delegates to the
2109      * method of the same name on the list's selection model.
2110      * <p>
2111      * Refer to the documentation of the selection model class being used
2112      * for details on how values less than {@code 0} are handled.
2113      *
2114      * @param index0 the first index to remove from the selection
2115      * @param index1 the last index to remove from the selection
2116      * @see ListSelectionModel#removeSelectionInterval
2117      * @see DefaultListSelectionModel#removeSelectionInterval
2118      * @see #createSelectionModel
2119      * @see #setSelectionInterval
2120      * @see #addSelectionInterval
2121      */
2122     public void removeSelectionInterval(int index0, int index1) {
2123         getSelectionModel().removeSelectionInterval(index0, index1);
2124     }
2125 
2126 
2127     /**
2128      * Sets the selection model's {@code valueIsAdjusting} property. When
2129      * {@code true}, upcoming changes to selection should be considered part
2130      * of a single change. This property is used internally and developers
2131      * typically need not call this method. For example, when the model is being
2132      * updated in response to a user drag, the value of the property is set
2133      * to {@code true} when the drag is initiated and set to {@code false}
2134      * when the drag is finished. This allows listeners to update only
2135      * when a change has been finalized, rather than handling all of the
2136      * intermediate values.
2137      * <p>
2138      * You may want to use this directly if making a series of changes
2139      * that should be considered part of a single change.
2140      * <p>
2141      * This is a cover method that delegates to the method of the same name on
2142      * the list's selection model. See the documentation for
2143      * {@link javax.swing.ListSelectionModel#setValueIsAdjusting} for
2144      * more details.
2145      *
2146      * @param b the new value for the property
2147      * @see ListSelectionModel#setValueIsAdjusting
2148      * @see javax.swing.event.ListSelectionEvent#getValueIsAdjusting
2149      * @see #getValueIsAdjusting
2150      */
2151     public void setValueIsAdjusting(boolean b) {
2152         getSelectionModel().setValueIsAdjusting(b);
2153     }
2154 
2155 
2156     /**
2157      * Returns the value of the selection model's {@code isAdjusting} property.
2158      * <p>
2159      * This is a cover method that delegates to the method of the same name on
2160      * the list's selection model.
2161      *
2162      * @return the value of the selection model's {@code isAdjusting} property.
2163      *
2164      * @see #setValueIsAdjusting
2165      * @see ListSelectionModel#getValueIsAdjusting
2166      */
2167     public boolean getValueIsAdjusting() {
2168         return getSelectionModel().getValueIsAdjusting();
2169     }
2170 
2171 
2172     /**
2173      * Returns an array of all of the selected indices, in increasing
2174      * order.
2175      *
2176      * @return all of the selected indices, in increasing order,
2177      *         or an empty array if nothing is selected
2178      * @see #removeSelectionInterval
2179      * @see #addListSelectionListener
2180      */
2181     @Transient
2182     public int[] getSelectedIndices() {
2183         ListSelectionModel sm = getSelectionModel();
2184         int iMin = sm.getMinSelectionIndex();
2185         int iMax = sm.getMaxSelectionIndex();
2186 
2187         if ((iMin < 0) || (iMax < 0)) {
2188             return new int[0];
2189         }
2190 
2191         int[] rvTmp = new int[1+ (iMax - iMin)];
2192         int n = 0;
2193         for(int i = iMin; i <= iMax; i++) {
2194             if (sm.isSelectedIndex(i)) {
2195                 rvTmp[n++] = i;
2196             }
2197         }
2198         int[] rv = new int[n];
2199         System.arraycopy(rvTmp, 0, rv, 0, n);
2200         return rv;
2201     }
2202 
2203 
2204     /**
2205      * Selects a single cell. Does nothing if the given index is greater
2206      * than or equal to the model size. This is a convenience method that uses
2207      * {@code setSelectionInterval} on the selection model. Refer to the
2208      * documentation for the selection model class being used for details on
2209      * how values less than {@code 0} are handled.
2210      *
2211      * @param index the index of the cell to select
2212      * @see ListSelectionModel#setSelectionInterval
2213      * @see #isSelectedIndex
2214      * @see #addListSelectionListener
2215      */
2216     @BeanProperty(bound = false, description
2217             = "The index of the selected cell.")
2218     public void setSelectedIndex(int index) {
2219         if (index >= getModel().getSize()) {
2220             return;
2221         }
2222         getSelectionModel().setSelectionInterval(index, index);
2223     }
2224 
2225 
2226     /**
2227      * Changes the selection to be the set of indices specified by the given
2228      * array. Indices greater than or equal to the model size are ignored.
2229      * This is a convenience method that clears the selection and then uses
2230      * {@code addSelectionInterval} on the selection model to add the indices.
2231      * Refer to the documentation of the selection model class being used for
2232      * details on how values less than {@code 0} are handled.
2233      *
2234      * @param indices an array of the indices of the cells to select,
2235      *                {@code non-null}
2236      * @see ListSelectionModel#addSelectionInterval
2237      * @see #isSelectedIndex
2238      * @see #addListSelectionListener
2239      * @throws NullPointerException if the given array is {@code null}
2240      */
2241     public void setSelectedIndices(int[] indices) {
2242         ListSelectionModel sm = getSelectionModel();
2243         sm.clearSelection();
2244         int size = getModel().getSize();
2245         for (int i : indices) {
2246             if (i < size) {
2247                 sm.addSelectionInterval(i, i);
2248             }
2249         }
2250     }
2251 
2252 
2253     /**
2254      * Returns an array of all the selected values, in increasing order based
2255      * on their indices in the list.
2256      *
2257      * @return the selected values, or an empty array if nothing is selected
2258      * @see #isSelectedIndex
2259      * @see #getModel
2260      * @see #addListSelectionListener
2261      *
2262      * @deprecated As of JDK 1.7, replaced by {@link #getSelectedValuesList()}
2263      */
2264     @Deprecated
2265     @BeanProperty(bound = false)
2266     public Object[] getSelectedValues() {
2267         ListSelectionModel sm = getSelectionModel();
2268         ListModel<E> dm = getModel();
2269 
2270         int iMin = sm.getMinSelectionIndex();
2271         int iMax = sm.getMaxSelectionIndex();
2272 
2273         if ((iMin < 0) || (iMax < 0)) {
2274             return new Object[0];
2275         }
2276 
2277         Object[] rvTmp = new Object[1+ (iMax - iMin)];
2278         int n = 0;
2279         for(int i = iMin; i <= iMax; i++) {
2280             if (sm.isSelectedIndex(i)) {
2281                 rvTmp[n++] = dm.getElementAt(i);
2282             }
2283         }
2284         Object[] rv = new Object[n];
2285         System.arraycopy(rvTmp, 0, rv, 0, n);
2286         return rv;
2287     }
2288 
2289     /**
2290      * Returns a list of all the selected items, in increasing order based
2291      * on their indices in the list.
2292      *
2293      * @return the selected items, or an empty list if nothing is selected
2294      * @see #isSelectedIndex
2295      * @see #getModel
2296      * @see #addListSelectionListener
2297      *
2298      * @since 1.7
2299      */
2300     @BeanProperty(bound = false)
2301     public List<E> getSelectedValuesList() {
2302         ListSelectionModel sm = getSelectionModel();
2303         ListModel<E> dm = getModel();
2304 
2305         int iMin = sm.getMinSelectionIndex();
2306         int iMax = sm.getMaxSelectionIndex();
2307 
2308         if ((iMin < 0) || (iMax < 0)) {
2309             return Collections.emptyList();
2310         }
2311 
2312         List<E> selectedItems = new ArrayList<E>();
2313         for(int i = iMin; i <= iMax; i++) {
2314             if (sm.isSelectedIndex(i)) {
2315                 selectedItems.add(dm.getElementAt(i));
2316             }
2317         }
2318         return selectedItems;
2319     }
2320 
2321 
2322     /**
2323      * Returns the smallest selected cell index; <i>the selection</i> when only
2324      * a single item is selected in the list. When multiple items are selected,
2325      * it is simply the smallest selected index. Returns {@code -1} if there is
2326      * no selection.
2327      * <p>
2328      * This method is a cover that delegates to {@code getMinSelectionIndex}.
2329      *
2330      * @return the smallest selected cell index
2331      * @see #getMinSelectionIndex
2332      * @see #addListSelectionListener
2333      */
2334     public int getSelectedIndex() {
2335         return getMinSelectionIndex();
2336     }
2337 
2338 
2339     /**
2340      * Returns the value for the smallest selected cell index;
2341      * <i>the selected value</i> when only a single item is selected in the
2342      * list. When multiple items are selected, it is simply the value for the
2343      * smallest selected index. Returns {@code null} if there is no selection.
2344      * <p>
2345      * This is a convenience method that simply returns the model value for
2346      * {@code getMinSelectionIndex}.
2347      *
2348      * @return the first selected value
2349      * @see #getMinSelectionIndex
2350      * @see #getModel
2351      * @see #addListSelectionListener
2352      */
2353     @BeanProperty(bound = false)
2354     public E getSelectedValue() {
2355         int i = getMinSelectionIndex();
2356         return (i == -1) ? null : getModel().getElementAt(i);
2357     }
2358 
2359 
2360     /**
2361      * Selects the specified object from the list.
2362      * If the object passed is not present in the list, the selection is
2363      * cleared.
2364      *
2365      * @param anObject      the object to select
2366      * @param shouldScroll  {@code true} if the list should scroll to display
2367      *                      the selected object, if one exists; otherwise {@code false}
2368      */
2369     public void setSelectedValue(Object anObject,boolean shouldScroll) {
2370         E selectedValue = getSelectedValue();
2371         //This will be true if both anObject and selectedObject are either
2372         // null or point to objects which return true on calling equals
2373         if((anObject == selectedValue) ||
2374                 (anObject != null && anObject.equals(selectedValue))) {
2375             return;
2376         } else {
2377             int i,c;
2378             ListModel<E> dm = getModel();
2379             for(i=0,c=dm.getSize();i<c;i++) {
2380                 Object object  = dm.getElementAt(i);
2381                 //Either both should be null or reference to objects which
2382                 // return true with equals method
2383                 if ((anObject == object) ||
2384                         anObject!= null && anObject.equals(object)) {
2385                     setSelectedIndex(i);
2386                     if (shouldScroll)
2387                         ensureIndexIsVisible(i);
2388                     repaint();  /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
2389                     return;
2390                 }
2391             }
2392             clearSelection();
2393         }
2394         repaint(); /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
2395     }
2396 
2397 
2398 
2399     /**
2400      * --- The Scrollable Implementation ---
2401      */
2402 
2403     private void checkScrollableParameters(Rectangle visibleRect, int orientation) {
2404         if (visibleRect == null) {
2405             throw new IllegalArgumentException("visibleRect must be non-null");
2406         }
2407         switch (orientation) {
2408         case SwingConstants.VERTICAL:
2409         case SwingConstants.HORIZONTAL:
2410             break;
2411         default:
2412             throw new IllegalArgumentException("orientation must be one of: VERTICAL, HORIZONTAL");
2413         }
2414     }
2415 
2416 
2417     /**
2418      * Computes the size of viewport needed to display {@code visibleRowCount}
2419      * rows. The value returned by this method depends on the layout
2420      * orientation:
2421      * <p>
2422      * <b>{@code VERTICAL}:</b>
2423      * <br>
2424      * This is trivial if both {@code fixedCellWidth} and {@code fixedCellHeight}
2425      * have been set (either explicitly or by specifying a prototype cell value).
2426      * The width is simply the {@code fixedCellWidth} plus the list's horizontal
2427      * insets. The height is the {@code fixedCellHeight} multiplied by the
2428      * {@code visibleRowCount}, plus the list's vertical insets.
2429      * <p>
2430      * If either {@code fixedCellWidth} or {@code fixedCellHeight} haven't been
2431      * specified, heuristics are used. If the model is empty, the width is
2432      * the {@code fixedCellWidth}, if greater than {@code 0}, or a hard-coded
2433      * value of {@code 256}. The height is the {@code fixedCellHeight} multiplied
2434      * by {@code visibleRowCount}, if {@code fixedCellHeight} is greater than
2435      * {@code 0}, otherwise it is a hard-coded value of {@code 16} multiplied by
2436      * {@code visibleRowCount}.
2437      * <p>
2438      * If the model isn't empty, the width is the preferred size's width,
2439      * typically the width of the widest list element. The height is the
2440      * {@code fixedCellHeight} multiplied by the {@code visibleRowCount},
2441      * plus the list's vertical insets.
2442      * <p>
2443      * <b>{@code VERTICAL_WRAP} or {@code HORIZONTAL_WRAP}:</b>
2444      * <br>
2445      * This method simply returns the value from {@code getPreferredSize}.
2446      * The list's {@code ListUI} is expected to override {@code getPreferredSize}
2447      * to return an appropriate value.
2448      *
2449      * @return a dimension containing the size of the viewport needed
2450      *          to display {@code visibleRowCount} rows
2451      * @see #getPreferredScrollableViewportSize
2452      * @see #setPrototypeCellValue
2453      */
2454     @BeanProperty(bound = false)
2455     public Dimension getPreferredScrollableViewportSize()
2456     {
2457         if (getLayoutOrientation() != VERTICAL) {
2458             return getPreferredSize();
2459         }
2460         Insets insets = getInsets();
2461         int dx = insets.left + insets.right;
2462         int dy = insets.top + insets.bottom;
2463 
2464         int visibleRowCount = getVisibleRowCount();
2465         int fixedCellWidth = getFixedCellWidth();
2466         int fixedCellHeight = getFixedCellHeight();
2467 
2468         if ((fixedCellWidth > 0) && (fixedCellHeight > 0)) {
2469             int width = fixedCellWidth + dx;
2470             int height = (visibleRowCount * fixedCellHeight) + dy;
2471             return new Dimension(width, height);
2472         }
2473         else if (getModel().getSize() > 0) {
2474             int width = getPreferredSize().width;
2475             int height;
2476             Rectangle r = getCellBounds(0, 0);
2477             if (r != null) {
2478                 height = (visibleRowCount * r.height) + dy;
2479             }
2480             else {
2481                 // Will only happen if UI null, shouldn't matter what we return
2482                 height = 1;
2483             }
2484             return new Dimension(width, height);
2485         }
2486         else {
2487             fixedCellWidth = (fixedCellWidth > 0) ? fixedCellWidth : 256;
2488             fixedCellHeight = (fixedCellHeight > 0) ? fixedCellHeight : 16;
2489             return new Dimension(fixedCellWidth, fixedCellHeight * visibleRowCount);
2490         }
2491     }
2492 
2493 
2494     /**
2495      * Returns the distance to scroll to expose the next or previous
2496      * row (for vertical scrolling) or column (for horizontal scrolling).
2497      * <p>
2498      * For horizontal scrolling, if the layout orientation is {@code VERTICAL},
2499      * then the list's font size is returned (or {@code 1} if the font is
2500      * {@code null}).
2501      *
2502      * @param visibleRect the view area visible within the viewport
2503      * @param orientation {@code SwingConstants.HORIZONTAL} or
2504      *                    {@code SwingConstants.VERTICAL}
2505      * @param direction less or equal to zero to scroll up/back,
2506      *                  greater than zero for down/forward
2507      * @return the "unit" increment for scrolling in the specified direction;
2508      *         always positive
2509      * @see #getScrollableBlockIncrement
2510      * @see Scrollable#getScrollableUnitIncrement
2511      * @throws IllegalArgumentException if {@code visibleRect} is {@code null}, or
2512      *         {@code orientation} isn't one of {@code SwingConstants.VERTICAL} or
2513      *         {@code SwingConstants.HORIZONTAL}
2514      */
2515     public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)
2516     {
2517         checkScrollableParameters(visibleRect, orientation);
2518 
2519         if (orientation == SwingConstants.VERTICAL) {
2520             int row = locationToIndex(visibleRect.getLocation());
2521 
2522             if (row == -1) {
2523                 return 0;
2524             }
2525             else {
2526                 /* Scroll Down */
2527                 if (direction > 0) {
2528                     Rectangle r = getCellBounds(row, row);
2529                     return (r == null) ? 0 : r.height - (visibleRect.y - r.y);
2530                 }
2531                 /* Scroll Up */
2532                 else {
2533                     Rectangle r = getCellBounds(row, row);
2534 
2535                     /* The first row is completely visible and it's row 0.
2536                      * We're done.
2537                      */
2538                     if ((r.y == visibleRect.y) && (row == 0))  {
2539                         return 0;
2540                     }
2541                     /* The first row is completely visible, return the
2542                      * height of the previous row or 0 if the first row
2543                      * is the top row of the list.
2544                      */
2545                     else if (r.y == visibleRect.y) {
2546                         Point loc = r.getLocation();
2547                         loc.y--;
2548                         int prevIndex = locationToIndex(loc);
2549                         Rectangle prevR = getCellBounds(prevIndex, prevIndex);
2550 
2551                         if (prevR == null || prevR.y >= r.y) {
2552                             return 0;
2553                         }
2554                         return prevR.height;
2555                     }
2556                     /* The first row is partially visible, return the
2557                      * height of hidden part.
2558                      */
2559                     else {
2560                         return visibleRect.y - r.y;
2561                     }
2562                 }
2563             }
2564         } else if (orientation == SwingConstants.HORIZONTAL &&
2565                            getLayoutOrientation() != JList.VERTICAL) {
2566             boolean leftToRight = getComponentOrientation().isLeftToRight();
2567             int index;
2568             Point leadingPoint;
2569 
2570             if (leftToRight) {
2571                 leadingPoint = visibleRect.getLocation();
2572             }
2573             else {
2574                 leadingPoint = new Point(visibleRect.x + visibleRect.width -1,
2575                                          visibleRect.y);
2576             }
2577             index = locationToIndex(leadingPoint);
2578 
2579             if (index != -1) {
2580                 Rectangle cellBounds = getCellBounds(index, index);
2581                 if (cellBounds != null && cellBounds.contains(leadingPoint)) {
2582                     int leadingVisibleEdge;
2583                     int leadingCellEdge;
2584 
2585                     if (leftToRight) {
2586                         leadingVisibleEdge = visibleRect.x;
2587                         leadingCellEdge = cellBounds.x;
2588                     }
2589                     else {
2590                         leadingVisibleEdge = visibleRect.x + visibleRect.width;
2591                         leadingCellEdge = cellBounds.x + cellBounds.width;
2592                     }
2593 
2594                     if (leadingCellEdge != leadingVisibleEdge) {
2595                         if (direction < 0) {
2596                             // Show remainder of leading cell
2597                             return Math.abs(leadingVisibleEdge - leadingCellEdge);
2598 
2599                         }
2600                         else if (leftToRight) {
2601                             // Hide rest of leading cell
2602                             return leadingCellEdge + cellBounds.width - leadingVisibleEdge;
2603                         }
2604                         else {
2605                             // Hide rest of leading cell
2606                             return leadingVisibleEdge - cellBounds.x;
2607                         }
2608                     }
2609                     // ASSUME: All cells are the same width
2610                     return cellBounds.width;
2611                 }
2612             }
2613         }
2614         Font f = getFont();
2615         return (f != null) ? f.getSize() : 1;
2616     }
2617 
2618 
2619     /**
2620      * Returns the distance to scroll to expose the next or previous block.
2621      * <p>
2622      * For vertical scrolling, the following rules are used:
2623      * <ul>
2624      * <li>if scrolling down, returns the distance to scroll so that the last
2625      * visible element becomes the first completely visible element
2626      * <li>if scrolling up, returns the distance to scroll so that the first
2627      * visible element becomes the last completely visible element
2628      * <li>returns {@code visibleRect.height} if the list is empty
2629      * </ul>
2630      * <p>
2631      * For horizontal scrolling, when the layout orientation is either
2632      * {@code VERTICAL_WRAP} or {@code HORIZONTAL_WRAP}:
2633      * <ul>
2634      * <li>if scrolling right, returns the distance to scroll so that the
2635      * last visible element becomes
2636      * the first completely visible element
2637      * <li>if scrolling left, returns the distance to scroll so that the first
2638      * visible element becomes the last completely visible element
2639      * <li>returns {@code visibleRect.width} if the list is empty
2640      * </ul>
2641      * <p>
2642      * For horizontal scrolling and {@code VERTICAL} orientation,
2643      * returns {@code visibleRect.width}.
2644      * <p>
2645      * Note that the value of {@code visibleRect} must be the equal to
2646      * {@code this.getVisibleRect()}.
2647      *
2648      * @param visibleRect the view area visible within the viewport
2649      * @param orientation {@code SwingConstants.HORIZONTAL} or
2650      *                    {@code SwingConstants.VERTICAL}
2651      * @param direction less or equal to zero to scroll up/back,
2652      *                  greater than zero for down/forward
2653      * @return the "block" increment for scrolling in the specified direction;
2654      *         always positive
2655      * @see #getScrollableUnitIncrement
2656      * @see Scrollable#getScrollableBlockIncrement
2657      * @throws IllegalArgumentException if {@code visibleRect} is {@code null}, or
2658      *         {@code orientation} isn't one of {@code SwingConstants.VERTICAL} or
2659      *         {@code SwingConstants.HORIZONTAL}
2660      */
2661     public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
2662         checkScrollableParameters(visibleRect, orientation);
2663         if (orientation == SwingConstants.VERTICAL) {
2664             int inc = visibleRect.height;
2665             /* Scroll Down */
2666             if (direction > 0) {
2667                 // last cell is the lowest left cell
2668                 int last = locationToIndex(new Point(visibleRect.x, visibleRect.y+visibleRect.height-1));
2669                 if (last != -1) {
2670                     Rectangle lastRect = getCellBounds(last,last);
2671                     if (lastRect != null) {
2672                         inc = lastRect.y - visibleRect.y;
2673                         if ( (inc == 0) && (last < getModel().getSize()-1) ) {
2674                             inc = lastRect.height;
2675                         }
2676                     }
2677                 }
2678             }
2679             /* Scroll Up */
2680             else {
2681                 int newFirst = locationToIndex(new Point(visibleRect.x, visibleRect.y-visibleRect.height));
2682                 int first = getFirstVisibleIndex();
2683                 if (newFirst != -1) {
2684                     if (first == -1) {
2685                         first = locationToIndex(visibleRect.getLocation());
2686                     }
2687                     Rectangle newFirstRect = getCellBounds(newFirst,newFirst);
2688                     Rectangle firstRect = getCellBounds(first,first);
2689                     if ((newFirstRect != null) && (firstRect!=null)) {
2690                         while ( (newFirstRect.y + visibleRect.height <
2691                                  firstRect.y + firstRect.height) &&
2692                                 (newFirstRect.y < firstRect.y) ) {
2693                             newFirst++;
2694                             newFirstRect = getCellBounds(newFirst,newFirst);
2695                         }
2696                         inc = visibleRect.y - newFirstRect.y;
2697                         if ( (inc <= 0) && (newFirstRect.y > 0)) {
2698                             newFirst--;
2699                             newFirstRect = getCellBounds(newFirst,newFirst);
2700                             if (newFirstRect != null) {
2701                                 inc = visibleRect.y - newFirstRect.y;
2702                             }
2703                         }
2704                     }
2705                 }
2706             }
2707             return inc;
2708         }
2709         else if (orientation == SwingConstants.HORIZONTAL &&
2710                  getLayoutOrientation() != JList.VERTICAL) {
2711             boolean leftToRight = getComponentOrientation().isLeftToRight();
2712             int inc = visibleRect.width;
2713             /* Scroll Right (in ltr mode) or Scroll Left (in rtl mode) */
2714             if (direction > 0) {
2715                 // position is upper right if ltr, or upper left otherwise
2716                 int x = visibleRect.x + (leftToRight ? (visibleRect.width - 1) : 0);
2717                 int last = locationToIndex(new Point(x, visibleRect.y));
2718 
2719                 if (last != -1) {
2720                     Rectangle lastRect = getCellBounds(last,last);
2721                     if (lastRect != null) {
2722                         if (leftToRight) {
2723                             inc = lastRect.x - visibleRect.x;
2724                         } else {
2725                             inc = visibleRect.x + visibleRect.width
2726                                       - (lastRect.x + lastRect.width);
2727                         }
2728                         if (inc < 0) {
2729                             inc += lastRect.width;
2730                         } else if ( (inc == 0) && (last < getModel().getSize()-1) ) {
2731                             inc = lastRect.width;
2732                         }
2733                     }
2734                 }
2735             }
2736             /* Scroll Left (in ltr mode) or Scroll Right (in rtl mode) */
2737             else {
2738                 // position is upper left corner of the visibleRect shifted
2739                 // left by the visibleRect.width if ltr, or upper right shifted
2740                 // right by the visibleRect.width otherwise
2741                 int x = visibleRect.x + (leftToRight
2742                                          ? -visibleRect.width
2743                                          : visibleRect.width - 1 + visibleRect.width);
2744                 int first = locationToIndex(new Point(x, visibleRect.y));
2745 
2746                 if (first != -1) {
2747                     Rectangle firstRect = getCellBounds(first,first);
2748                     if (firstRect != null) {
2749                         // the right of the first cell
2750                         int firstRight = firstRect.x + firstRect.width;
2751 
2752                         if (leftToRight) {
2753                             if ((firstRect.x < visibleRect.x - visibleRect.width)
2754                                     && (firstRight < visibleRect.x)) {
2755                                 inc = visibleRect.x - firstRight;
2756                             } else {
2757                                 inc = visibleRect.x - firstRect.x;
2758                             }
2759                         } else {
2760                             int visibleRight = visibleRect.x + visibleRect.width;
2761 
2762                             if ((firstRight > visibleRight + visibleRect.width)
2763                                     && (firstRect.x > visibleRight)) {
2764                                 inc = firstRect.x - visibleRight;
2765                             } else {
2766                                 inc = firstRight - visibleRight;
2767                             }
2768                         }
2769                     }
2770                 }
2771             }
2772             return inc;
2773         }
2774         return visibleRect.width;
2775     }
2776 
2777 
2778     /**
2779      * Returns {@code true} if this {@code JList} is displayed in a
2780      * {@code JViewport} and the viewport is wider than the list's
2781      * preferred width, or if the layout orientation is {@code HORIZONTAL_WRAP}
2782      * and {@code visibleRowCount <= 0}; otherwise returns {@code false}.
2783      * <p>
2784      * If {@code false}, then don't track the viewport's width. This allows
2785      * horizontal scrolling if the {@code JViewport} is itself embedded in a
2786      * {@code JScrollPane}.
2787      *
2788      * @return whether or not an enclosing viewport should force the list's
2789      *         width to match its own
2790      * @see Scrollable#getScrollableTracksViewportWidth
2791      */
2792     @BeanProperty(bound = false)
2793     public boolean getScrollableTracksViewportWidth() {
2794         if (getLayoutOrientation() == HORIZONTAL_WRAP &&
2795                                       getVisibleRowCount() <= 0) {
2796             return true;
2797         }
2798         Container parent = SwingUtilities.getUnwrappedParent(this);
2799         if (parent instanceof JViewport) {
2800             return parent.getWidth() > getPreferredSize().width;
2801         }
2802         return false;
2803     }
2804 
2805     /**
2806      * Returns {@code true} if this {@code JList} is displayed in a
2807      * {@code JViewport} and the viewport is taller than the list's
2808      * preferred height, or if the layout orientation is {@code VERTICAL_WRAP}
2809      * and {@code visibleRowCount <= 0}; otherwise returns {@code false}.
2810      * <p>
2811      * If {@code false}, then don't track the viewport's height. This allows
2812      * vertical scrolling if the {@code JViewport} is itself embedded in a
2813      * {@code JScrollPane}.
2814      *
2815      * @return whether or not an enclosing viewport should force the list's
2816      *         height to match its own
2817      * @see Scrollable#getScrollableTracksViewportHeight
2818      */
2819     @BeanProperty(bound = false)
2820     public boolean getScrollableTracksViewportHeight() {
2821         if (getLayoutOrientation() == VERTICAL_WRAP &&
2822                      getVisibleRowCount() <= 0) {
2823             return true;
2824         }
2825         Container parent = SwingUtilities.getUnwrappedParent(this);
2826         if (parent instanceof JViewport) {
2827             return parent.getHeight() > getPreferredSize().height;
2828         }
2829         return false;
2830     }
2831 
2832 
2833     /*
2834      * See {@code readObject} and {@code writeObject} in {@code JComponent}
2835      * for more information about serialization in Swing.
2836      */
2837     private void writeObject(ObjectOutputStream s) throws IOException {
2838         s.defaultWriteObject();
2839         if (getUIClassID().equals(uiClassID)) {
2840             byte count = JComponent.getWriteObjCounter(this);
2841             JComponent.setWriteObjCounter(this, --count);
2842             if (count == 0 && ui != null) {
2843                 ui.installUI(this);
2844             }
2845         }
2846     }
2847 
2848 
2849     /**
2850      * Returns a {@code String} representation of this {@code JList}.
2851      * This method is intended to be used only for debugging purposes,
2852      * and the content and format of the returned {@code String} may vary
2853      * between implementations. The returned {@code String} may be empty,
2854      * but may not be {@code null}.
2855      *
2856      * @return  a {@code String} representation of this {@code JList}.
2857      */
2858     protected String paramString() {
2859         String selectionForegroundString = (selectionForeground != null ?
2860                                             selectionForeground.toString() :
2861                                             "");
2862         String selectionBackgroundString = (selectionBackground != null ?
2863                                             selectionBackground.toString() :
2864                                             "");
2865 
2866         return super.paramString() +
2867         ",fixedCellHeight=" + fixedCellHeight +
2868         ",fixedCellWidth=" + fixedCellWidth +
2869         ",horizontalScrollIncrement=" + horizontalScrollIncrement +
2870         ",selectionBackground=" + selectionBackgroundString +
2871         ",selectionForeground=" + selectionForegroundString +
2872         ",visibleRowCount=" + visibleRowCount +
2873         ",layoutOrientation=" + layoutOrientation;
2874     }
2875 
2876 
2877     /**
2878      * --- Accessibility Support ---
2879      */
2880 
2881     /**
2882      * Gets the {@code AccessibleContext} associated with this {@code JList}.
2883      * For {@code JList}, the {@code AccessibleContext} takes the form of an
2884      * {@code AccessibleJList}.
2885      * <p>
2886      * A new {@code AccessibleJList} instance is created if necessary.
2887      *
2888      * @return an {@code AccessibleJList} that serves as the
2889      *         {@code AccessibleContext} of this {@code JList}
2890      */
2891     @BeanProperty(bound = false)
2892     public AccessibleContext getAccessibleContext() {
2893         if (accessibleContext == null) {
2894             accessibleContext = new AccessibleJList();
2895         }
2896         return accessibleContext;
2897     }
2898 
2899     /**
2900      * This class implements accessibility support for the
2901      * {@code JList} class. It provides an implementation of the
2902      * Java Accessibility API appropriate to list user-interface
2903      * elements.
2904      * <p>
2905      * <strong>Warning:</strong>
2906      * Serialized objects of this class will not be compatible with
2907      * future Swing releases. The current serialization support is
2908      * appropriate for short term storage or RMI between applications running
2909      * the same version of Swing.  As of 1.4, support for long term storage
2910      * of all JavaBeans&trade;
2911      * has been added to the <code>java.beans</code> package.
2912      * Please see {@link java.beans.XMLEncoder}.
2913      */
2914     @SuppressWarnings("serial") // Same-version serialization only
2915     protected class AccessibleJList extends AccessibleJComponent
2916         implements AccessibleSelection, PropertyChangeListener,
2917         ListSelectionListener, ListDataListener {
2918 
2919         int leadSelectionIndex;
2920 
2921         /**
2922          * Constructs an {@code AccessibleJList}.
2923          */
2924         public AccessibleJList() {
2925             super();
2926             JList.this.addPropertyChangeListener(this);
2927             JList.this.getSelectionModel().addListSelectionListener(this);
2928             JList.this.getModel().addListDataListener(this);
2929             leadSelectionIndex = JList.this.getLeadSelectionIndex();
2930         }
2931 
2932         /**
2933          * Property Change Listener change method. Used to track changes
2934          * to the DataModel and ListSelectionModel, in order to re-set
2935          * listeners to those for reporting changes there via the Accessibility
2936          * PropertyChange mechanism.
2937          *
2938          * @param e PropertyChangeEvent
2939          */
2940         public void propertyChange(PropertyChangeEvent e) {
2941             String name = e.getPropertyName();
2942             Object oldValue = e.getOldValue();
2943             Object newValue = e.getNewValue();
2944 
2945                 // re-set listData listeners
2946             if (name.compareTo("model") == 0) {
2947 
2948                 if (oldValue != null && oldValue instanceof ListModel) {
2949                     ((ListModel) oldValue).removeListDataListener(this);
2950                 }
2951                 if (newValue != null && newValue instanceof ListModel) {
2952                     ((ListModel) newValue).addListDataListener(this);
2953                 }
2954 
2955                 // re-set listSelectionModel listeners
2956             } else if (name.compareTo("selectionModel") == 0) {
2957 
2958                 if (oldValue != null && oldValue instanceof ListSelectionModel) {
2959                     ((ListSelectionModel) oldValue).removeListSelectionListener(this);
2960                 }
2961                 if (newValue != null && newValue instanceof ListSelectionModel) {
2962                     ((ListSelectionModel) newValue).addListSelectionListener(this);
2963                 }
2964 
2965                 firePropertyChange(
2966                     AccessibleContext.ACCESSIBLE_SELECTION_PROPERTY,
2967                     Boolean.valueOf(false), Boolean.valueOf(true));
2968             }
2969         }
2970 
2971         /**
2972          * List Selection Listener value change method. Used to fire
2973          * the property change
2974          *
2975          * @param e ListSelectionEvent
2976          *
2977          */
2978         public void valueChanged(ListSelectionEvent e) {
2979             int oldLeadSelectionIndex = leadSelectionIndex;
2980             leadSelectionIndex = JList.this.getLeadSelectionIndex();
2981             if (oldLeadSelectionIndex != leadSelectionIndex) {
2982                 Accessible oldLS, newLS;
2983                 oldLS = (oldLeadSelectionIndex >= 0)
2984                         ? getAccessibleChild(oldLeadSelectionIndex)
2985                         : null;
2986                 newLS = (leadSelectionIndex >= 0)
2987                         ? getAccessibleChild(leadSelectionIndex)
2988                         : null;
2989                 firePropertyChange(AccessibleContext.ACCESSIBLE_ACTIVE_DESCENDANT_PROPERTY,
2990                                    oldLS, newLS);
2991             }
2992 
2993             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
2994                                Boolean.valueOf(false), Boolean.valueOf(true));
2995             firePropertyChange(AccessibleContext.ACCESSIBLE_SELECTION_PROPERTY,
2996                                Boolean.valueOf(false), Boolean.valueOf(true));
2997 
2998             // Process the State changes for Multiselectable
2999             AccessibleStateSet s = getAccessibleStateSet();
3000             ListSelectionModel lsm = JList.this.getSelectionModel();
3001             if (lsm.getSelectionMode() != ListSelectionModel.SINGLE_SELECTION) {
3002                 if (!s.contains(AccessibleState.MULTISELECTABLE)) {
3003                     s.add(AccessibleState.MULTISELECTABLE);
3004                     firePropertyChange(AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
3005                                        null, AccessibleState.MULTISELECTABLE);
3006                 }
3007             } else {
3008                 if (s.contains(AccessibleState.MULTISELECTABLE)) {
3009                     s.remove(AccessibleState.MULTISELECTABLE);
3010                     firePropertyChange(AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
3011                                        AccessibleState.MULTISELECTABLE, null);
3012                 }
3013             }
3014         }
3015 
3016         /**
3017          * List Data Listener interval added method. Used to fire the visible data property change
3018          *
3019          * @param e ListDataEvent
3020          *
3021          */
3022         public void intervalAdded(ListDataEvent e) {
3023             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3024                                Boolean.valueOf(false), Boolean.valueOf(true));
3025         }
3026 
3027         /**
3028          * List Data Listener interval removed method. Used to fire the visible data property change
3029          *
3030          * @param e ListDataEvent
3031          *
3032          */
3033         public void intervalRemoved(ListDataEvent e) {
3034             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3035                                Boolean.valueOf(false), Boolean.valueOf(true));
3036         }
3037 
3038         /**
3039          * List Data Listener contents changed method. Used to fire the visible data property change
3040          *
3041          * @param e ListDataEvent
3042          *
3043          */
3044          public void contentsChanged(ListDataEvent e) {
3045              firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3046                                 Boolean.valueOf(false), Boolean.valueOf(true));
3047          }
3048 
3049     // AccessibleContext methods
3050 
3051         /**
3052          * Get the state set of this object.
3053          *
3054          * @return an instance of AccessibleState containing the current state
3055          * of the object
3056          * @see AccessibleState
3057          */
3058         public AccessibleStateSet getAccessibleStateSet() {
3059             AccessibleStateSet states = super.getAccessibleStateSet();
3060             if (selectionModel.getSelectionMode() !=
3061                 ListSelectionModel.SINGLE_SELECTION) {
3062                 states.add(AccessibleState.MULTISELECTABLE);
3063             }
3064             return states;
3065         }
3066 
3067         /**
3068          * Get the role of this object.
3069          *
3070          * @return an instance of AccessibleRole describing the role of the
3071          * object
3072          * @see AccessibleRole
3073          */
3074         public AccessibleRole getAccessibleRole() {
3075             return AccessibleRole.LIST;
3076         }
3077 
3078         /**
3079          * Returns the <code>Accessible</code> child contained at
3080          * the local coordinate <code>Point</code>, if one exists.
3081          * Otherwise returns <code>null</code>.
3082          *
3083          * @return the <code>Accessible</code> at the specified
3084          *    location, if it exists
3085          */
3086         public Accessible getAccessibleAt(Point p) {
3087             int i = locationToIndex(p);
3088             if (i >= 0) {
3089                 return new AccessibleJListChild(JList.this, i);
3090             } else {
3091                 return null;
3092             }
3093         }
3094 
3095         /**
3096          * Returns the number of accessible children in the object.  If all
3097          * of the children of this object implement Accessible, than this
3098          * method should return the number of children of this object.
3099          *
3100          * @return the number of accessible children in the object.
3101          */
3102         public int getAccessibleChildrenCount() {
3103             return getModel().getSize();
3104         }
3105 
3106         /**
3107          * Return the nth Accessible child of the object.
3108          *
3109          * @param i zero-based index of child
3110          * @return the nth Accessible child of the object
3111          */
3112         public Accessible getAccessibleChild(int i) {
3113             if (i >= getModel().getSize()) {
3114                 return null;
3115             } else {
3116                 return new AccessibleJListChild(JList.this, i);
3117             }
3118         }
3119 
3120         /**
3121          * Get the AccessibleSelection associated with this object.  In the
3122          * implementation of the Java Accessibility API for this class,
3123          * return this object, which is responsible for implementing the
3124          * AccessibleSelection interface on behalf of itself.
3125          *
3126          * @return this object
3127          */
3128         public AccessibleSelection getAccessibleSelection() {
3129             return this;
3130         }
3131 
3132 
3133     // AccessibleSelection methods
3134 
3135         /**
3136          * Returns the number of items currently selected.
3137          * If no items are selected, the return value will be 0.
3138          *
3139          * @return the number of items currently selected.
3140          */
3141          public int getAccessibleSelectionCount() {
3142              return JList.this.getSelectedIndices().length;
3143          }
3144 
3145         /**
3146          * Returns an Accessible representing the specified selected item
3147          * in the object.  If there isn't a selection, or there are
3148          * fewer items selected than the integer passed in, the return
3149          * value will be <code>null</code>.
3150          *
3151          * @param i the zero-based index of selected items
3152          * @return an Accessible containing the selected item
3153          */
3154          public Accessible getAccessibleSelection(int i) {
3155              int len = getAccessibleSelectionCount();
3156              if (i < 0 || i >= len) {
3157                  return null;
3158              } else {
3159                  return getAccessibleChild(JList.this.getSelectedIndices()[i]);
3160              }
3161          }
3162 
3163         /**
3164          * Returns true if the current child of this object is selected.
3165          *
3166          * @param i the zero-based index of the child in this Accessible
3167          * object.
3168          * @see AccessibleContext#getAccessibleChild
3169          */
3170         public boolean isAccessibleChildSelected(int i) {
3171             return isSelectedIndex(i);
3172         }
3173 
3174         /**
3175          * Adds the specified selected item in the object to the object's
3176          * selection.  If the object supports multiple selections,
3177          * the specified item is added to any existing selection, otherwise
3178          * it replaces any existing selection in the object.  If the
3179          * specified item is already selected, this method has no effect.
3180          *
3181          * @param i the zero-based index of selectable items
3182          */
3183          public void addAccessibleSelection(int i) {
3184              JList.this.addSelectionInterval(i, i);
3185          }
3186 
3187         /**
3188          * Removes the specified selected item in the object from the object's
3189          * selection.  If the specified item isn't currently selected, this
3190          * method has no effect.
3191          *
3192          * @param i the zero-based index of selectable items
3193          */
3194          public void removeAccessibleSelection(int i) {
3195              JList.this.removeSelectionInterval(i, i);
3196          }
3197 
3198         /**
3199          * Clears the selection in the object, so that nothing in the
3200          * object is selected.
3201          */
3202          public void clearAccessibleSelection() {
3203              JList.this.clearSelection();
3204          }
3205 
3206         /**
3207          * Causes every selected item in the object to be selected
3208          * if the object supports multiple selections.
3209          */
3210          public void selectAllAccessibleSelection() {
3211              JList.this.addSelectionInterval(0, getAccessibleChildrenCount() -1);
3212          }
3213 
3214           /**
3215            * This class implements accessibility support appropriate
3216            * for list children.
3217            */
3218         protected class AccessibleJListChild extends AccessibleContext
3219                 implements Accessible, AccessibleComponent, AccessibleAction {
3220             private JList<E>     parent = null;
3221             int indexInParent;
3222             private Component component = null;
3223             private AccessibleContext accessibleContext = null;
3224             private ListModel<E> listModel;
3225             private ListCellRenderer<? super E> cellRenderer = null;
3226 
3227             /**
3228              * Constructs an {@code AccessibleJListChild}.
3229              * @param parent the parent
3230              * @param indexInParent the index in the parent
3231              */
3232             public AccessibleJListChild(JList<E> parent, int indexInParent) {
3233                 this.parent = parent;
3234                 this.setAccessibleParent(parent);
3235                 this.indexInParent = indexInParent;
3236                 if (parent != null) {
3237                     listModel = parent.getModel();
3238                     cellRenderer = parent.getCellRenderer();
3239                 }
3240             }
3241 
3242             private Component getCurrentComponent() {
3243                 return getComponentAtIndex(indexInParent);
3244             }
3245 
3246             AccessibleContext getCurrentAccessibleContext() {
3247                 Component c = getComponentAtIndex(indexInParent);
3248                 if (c instanceof Accessible) {
3249                     return c.getAccessibleContext();
3250                 } else {
3251                     return null;
3252                 }
3253             }
3254 
3255             private Component getComponentAtIndex(int index) {
3256                 if (index < 0 || index >= listModel.getSize()) {
3257                     return null;
3258                 }
3259                 if ((parent != null)
3260                         && (listModel != null)
3261                         && cellRenderer != null) {
3262                     E value = listModel.getElementAt(index);
3263                     boolean isSelected = parent.isSelectedIndex(index);
3264                     boolean isFocussed = parent.isFocusOwner()
3265                             && (index == parent.getLeadSelectionIndex());
3266                     return cellRenderer.getListCellRendererComponent(
3267                             parent,
3268                             value,
3269                             index,
3270                             isSelected,
3271                             isFocussed);
3272                 } else {
3273                     return null;
3274                 }
3275             }
3276 
3277 
3278             // Accessible Methods
3279            /**
3280             * Get the AccessibleContext for this object. In the
3281             * implementation of the Java Accessibility API for this class,
3282             * returns this object, which is its own AccessibleContext.
3283             *
3284             * @return this object
3285             */
3286             public AccessibleContext getAccessibleContext() {
3287                 return this;
3288             }
3289 
3290 
3291             // AccessibleContext methods
3292 
3293             public String getAccessibleName() {
3294                 AccessibleContext ac = getCurrentAccessibleContext();
3295                 if (ac != null) {
3296                     return ac.getAccessibleName();
3297                 } else {
3298                     return null;
3299                 }
3300             }
3301 
3302             public void setAccessibleName(String s) {
3303                 AccessibleContext ac = getCurrentAccessibleContext();
3304                 if (ac != null) {
3305                     ac.setAccessibleName(s);
3306                 }
3307             }
3308 
3309             public String getAccessibleDescription() {
3310                 AccessibleContext ac = getCurrentAccessibleContext();
3311                 if (ac != null) {
3312                     return ac.getAccessibleDescription();
3313                 } else {
3314                     return null;
3315                 }
3316             }
3317 
3318             public void setAccessibleDescription(String s) {
3319                 AccessibleContext ac = getCurrentAccessibleContext();
3320                 if (ac != null) {
3321                     ac.setAccessibleDescription(s);
3322                 }
3323             }
3324 
3325             public AccessibleRole getAccessibleRole() {
3326                 AccessibleContext ac = getCurrentAccessibleContext();
3327                 if (ac != null) {
3328                     return ac.getAccessibleRole();
3329                 } else {
3330                     return null;
3331                 }
3332             }
3333 
3334             public AccessibleStateSet getAccessibleStateSet() {
3335                 AccessibleContext ac = getCurrentAccessibleContext();
3336                 AccessibleStateSet s;
3337                 if (ac != null) {
3338                     s = ac.getAccessibleStateSet();
3339                 } else {
3340                     s = new AccessibleStateSet();
3341                 }
3342 
3343                 s.add(AccessibleState.SELECTABLE);
3344                 if (parent.isFocusOwner()
3345                     && (indexInParent == parent.getLeadSelectionIndex())) {
3346                     s.add(AccessibleState.ACTIVE);
3347                 }
3348                 if (parent.isSelectedIndex(indexInParent)) {
3349                     s.add(AccessibleState.SELECTED);
3350                 }
3351                 if (this.isShowing()) {
3352                     s.add(AccessibleState.SHOWING);
3353                 } else if (s.contains(AccessibleState.SHOWING)) {
3354                     s.remove(AccessibleState.SHOWING);
3355                 }
3356                 if (this.isVisible()) {
3357                     s.add(AccessibleState.VISIBLE);
3358                 } else if (s.contains(AccessibleState.VISIBLE)) {
3359                     s.remove(AccessibleState.VISIBLE);
3360                 }
3361                 s.add(AccessibleState.TRANSIENT); // cell-rendered
3362                 return s;
3363             }
3364 
3365             public int getAccessibleIndexInParent() {
3366                 return indexInParent;
3367             }
3368 
3369             public int getAccessibleChildrenCount() {
3370                 AccessibleContext ac = getCurrentAccessibleContext();
3371                 if (ac != null) {
3372                     return ac.getAccessibleChildrenCount();
3373                 } else {
3374                     return 0;
3375                 }
3376             }
3377 
3378             public Accessible getAccessibleChild(int i) {
3379                 AccessibleContext ac = getCurrentAccessibleContext();
3380                 if (ac != null) {
3381                     Accessible accessibleChild = ac.getAccessibleChild(i);
3382                     ac.setAccessibleParent(this);
3383                     return accessibleChild;
3384                 } else {
3385                     return null;
3386                 }
3387             }
3388 
3389             public Locale getLocale() {
3390                 AccessibleContext ac = getCurrentAccessibleContext();
3391                 if (ac != null) {
3392                     return ac.getLocale();
3393                 } else {
3394                     return null;
3395                 }
3396             }
3397 
3398             public void addPropertyChangeListener(PropertyChangeListener l) {
3399                 AccessibleContext ac = getCurrentAccessibleContext();
3400                 if (ac != null) {
3401                     ac.addPropertyChangeListener(l);
3402                 }
3403             }
3404 
3405             public void removePropertyChangeListener(PropertyChangeListener l) {
3406                 AccessibleContext ac = getCurrentAccessibleContext();
3407                 if (ac != null) {
3408                     ac.removePropertyChangeListener(l);
3409                 }
3410             }
3411 
3412            /**
3413             * Get the AccessibleComponent associated with this object.  In the
3414             * implementation of the Java Accessibility API for this class,
3415             * return this object, which is responsible for implementing the
3416             * AccessibleComponent interface on behalf of itself.
3417             *
3418             * @return this object
3419             */
3420             public AccessibleComponent getAccessibleComponent() {
3421                 return this; // to override getBounds()
3422             }
3423 
3424             public AccessibleSelection getAccessibleSelection() {
3425                 AccessibleContext ac = getCurrentAccessibleContext();
3426                 return ac != null ? ac.getAccessibleSelection() : null;
3427             }
3428 
3429             public AccessibleText getAccessibleText() {
3430                 AccessibleContext ac = getCurrentAccessibleContext();
3431                 return ac != null ? ac.getAccessibleText() : null;
3432             }
3433 
3434             public AccessibleValue getAccessibleValue() {
3435                 AccessibleContext ac = getCurrentAccessibleContext();
3436                 return ac != null ? ac.getAccessibleValue() : null;
3437             }
3438 
3439 
3440             // AccessibleComponent methods
3441 
3442             public Color getBackground() {
3443                 AccessibleContext ac = getCurrentAccessibleContext();
3444                 if (ac instanceof AccessibleComponent) {
3445                     return ((AccessibleComponent) ac).getBackground();
3446                 } else {
3447                     Component c = getCurrentComponent();
3448                     if (c != null) {
3449                         return c.getBackground();
3450                     } else {
3451                         return null;
3452                     }
3453                 }
3454             }
3455 
3456             public void setBackground(Color c) {
3457                 AccessibleContext ac = getCurrentAccessibleContext();
3458                 if (ac instanceof AccessibleComponent) {
3459                     ((AccessibleComponent) ac).setBackground(c);
3460                 } else {
3461                     Component cp = getCurrentComponent();
3462                     if (cp != null) {
3463                         cp.setBackground(c);
3464                     }
3465                 }
3466             }
3467 
3468             public Color getForeground() {
3469                 AccessibleContext ac = getCurrentAccessibleContext();
3470                 if (ac instanceof AccessibleComponent) {
3471                     return ((AccessibleComponent) ac).getForeground();
3472                 } else {
3473                     Component c = getCurrentComponent();
3474                     if (c != null) {
3475                         return c.getForeground();
3476                     } else {
3477                         return null;
3478                     }
3479                 }
3480             }
3481 
3482             public void setForeground(Color c) {
3483                 AccessibleContext ac = getCurrentAccessibleContext();
3484                 if (ac instanceof AccessibleComponent) {
3485                     ((AccessibleComponent) ac).setForeground(c);
3486                 } else {
3487                     Component cp = getCurrentComponent();
3488                     if (cp != null) {
3489                         cp.setForeground(c);
3490                     }
3491                 }
3492             }
3493 
3494             public Cursor getCursor() {
3495                 AccessibleContext ac = getCurrentAccessibleContext();
3496                 if (ac instanceof AccessibleComponent) {
3497                     return ((AccessibleComponent) ac).getCursor();
3498                 } else {
3499                     Component c = getCurrentComponent();
3500                     if (c != null) {
3501                         return c.getCursor();
3502                     } else {
3503                         Accessible ap = getAccessibleParent();
3504                         if (ap instanceof AccessibleComponent) {
3505                             return ((AccessibleComponent) ap).getCursor();
3506                         } else {
3507                             return null;
3508                         }
3509                     }
3510                 }
3511             }
3512 
3513             public void setCursor(Cursor c) {
3514                 AccessibleContext ac = getCurrentAccessibleContext();
3515                 if (ac instanceof AccessibleComponent) {
3516                     ((AccessibleComponent) ac).setCursor(c);
3517                 } else {
3518                     Component cp = getCurrentComponent();
3519                     if (cp != null) {
3520                         cp.setCursor(c);
3521                     }
3522                 }
3523             }
3524 
3525             public Font getFont() {
3526                 AccessibleContext ac = getCurrentAccessibleContext();
3527                 if (ac instanceof AccessibleComponent) {
3528                     return ((AccessibleComponent) ac).getFont();
3529                 } else {
3530                     Component c = getCurrentComponent();
3531                     if (c != null) {
3532                         return c.getFont();
3533                     } else {
3534                         return null;
3535                     }
3536                 }
3537             }
3538 
3539             public void setFont(Font f) {
3540                 AccessibleContext ac = getCurrentAccessibleContext();
3541                 if (ac instanceof AccessibleComponent) {
3542                     ((AccessibleComponent) ac).setFont(f);
3543                 } else {
3544                     Component c = getCurrentComponent();
3545                     if (c != null) {
3546                         c.setFont(f);
3547                     }
3548                 }
3549             }
3550 
3551             public FontMetrics getFontMetrics(Font f) {
3552                 AccessibleContext ac = getCurrentAccessibleContext();
3553                 if (ac instanceof AccessibleComponent) {
3554                     return ((AccessibleComponent) ac).getFontMetrics(f);
3555                 } else {
3556                     Component c = getCurrentComponent();
3557                     if (c != null) {
3558                         return c.getFontMetrics(f);
3559                     } else {
3560                         return null;
3561                     }
3562                 }
3563             }
3564 
3565             public boolean isEnabled() {
3566                 AccessibleContext ac = getCurrentAccessibleContext();
3567                 if (ac instanceof AccessibleComponent) {
3568                     return ((AccessibleComponent) ac).isEnabled();
3569                 } else {
3570                     Component c = getCurrentComponent();
3571                     if (c != null) {
3572                         return c.isEnabled();
3573                     } else {
3574                         return false;
3575                     }
3576                 }
3577             }
3578 
3579             public void setEnabled(boolean b) {
3580                 AccessibleContext ac = getCurrentAccessibleContext();
3581                 if (ac instanceof AccessibleComponent) {
3582                     ((AccessibleComponent) ac).setEnabled(b);
3583                 } else {
3584                     Component c = getCurrentComponent();
3585                     if (c != null) {
3586                         c.setEnabled(b);
3587                     }
3588                 }
3589             }
3590 
3591             public boolean isVisible() {
3592                 int fi = parent.getFirstVisibleIndex();
3593                 int li = parent.getLastVisibleIndex();
3594                 // The UI incorrectly returns a -1 for the last
3595                 // visible index if the list is smaller than the
3596                 // viewport size.
3597                 if (li == -1) {
3598                     li = parent.getModel().getSize() - 1;
3599                 }
3600                 return ((indexInParent >= fi)
3601                         && (indexInParent <= li));
3602             }
3603 
3604             public void setVisible(boolean b) {
3605             }
3606 
3607             public boolean isShowing() {
3608                 return (parent.isShowing() && isVisible());
3609             }
3610 
3611             public boolean contains(Point p) {
3612                 AccessibleContext ac = getCurrentAccessibleContext();
3613                 if (ac instanceof AccessibleComponent) {
3614                     Rectangle r = ((AccessibleComponent) ac).getBounds();
3615                     return r.contains(p);
3616                 } else {
3617                     Component c = getCurrentComponent();
3618                     if (c != null) {
3619                         Rectangle r = c.getBounds();
3620                         return r.contains(p);
3621                     } else {
3622                         return getBounds().contains(p);
3623                     }
3624                 }
3625             }
3626 
3627             public Point getLocationOnScreen() {
3628                 if (parent != null) {
3629                     Point listLocation;
3630                     try {
3631                         listLocation = parent.getLocationOnScreen();
3632                     } catch (IllegalComponentStateException e) {
3633                         // This can happen if the component isn't visisble
3634                         return null;
3635                     }
3636                     Point componentLocation = parent.indexToLocation(indexInParent);
3637                     if (componentLocation != null) {
3638                         componentLocation.translate(listLocation.x, listLocation.y);
3639                         return componentLocation;
3640                     } else {
3641                         return null;
3642                     }
3643                 } else {
3644                     return null;
3645                 }
3646             }
3647 
3648             public Point getLocation() {
3649                 if (parent != null) {
3650                     return parent.indexToLocation(indexInParent);
3651                 } else {
3652                     return null;
3653                 }
3654             }
3655 
3656             public void setLocation(Point p) {
3657                 if ((parent != null)  && (parent.contains(p))) {
3658                     ensureIndexIsVisible(indexInParent);
3659                 }
3660             }
3661 
3662             public Rectangle getBounds() {
3663                 if (parent != null) {
3664                     return parent.getCellBounds(indexInParent,indexInParent);
3665                 } else {
3666                     return null;
3667                 }
3668             }
3669 
3670             public void setBounds(Rectangle r) {
3671                 AccessibleContext ac = getCurrentAccessibleContext();
3672                 if (ac instanceof AccessibleComponent) {
3673                     ((AccessibleComponent) ac).setBounds(r);
3674                 }
3675             }
3676 
3677             public Dimension getSize() {
3678                 Rectangle cellBounds = this.getBounds();
3679                 if (cellBounds != null) {
3680                     return cellBounds.getSize();
3681                 } else {
3682                     return null;
3683                 }
3684             }
3685 
3686             public void setSize (Dimension d) {
3687                 AccessibleContext ac = getCurrentAccessibleContext();
3688                 if (ac instanceof AccessibleComponent) {
3689                     ((AccessibleComponent) ac).setSize(d);
3690                 } else {
3691                     Component c = getCurrentComponent();
3692                     if (c != null) {
3693                         c.setSize(d);
3694                     }
3695                 }
3696             }
3697 
3698             public Accessible getAccessibleAt(Point p) {
3699                 AccessibleContext ac = getCurrentAccessibleContext();
3700                 if (ac instanceof AccessibleComponent) {
3701                     return ((AccessibleComponent) ac).getAccessibleAt(p);
3702                 } else {
3703                     return null;
3704                 }
3705             }
3706 
3707             @SuppressWarnings("deprecation")
3708             public boolean isFocusTraversable() {
3709                 AccessibleContext ac = getCurrentAccessibleContext();
3710                 if (ac instanceof AccessibleComponent) {
3711                     return ((AccessibleComponent) ac).isFocusTraversable();
3712                 } else {
3713                     Component c = getCurrentComponent();
3714                     if (c != null) {
3715                         return c.isFocusTraversable();
3716                     } else {
3717                         return false;
3718                     }
3719                 }
3720             }
3721 
3722             public void requestFocus() {
3723                 AccessibleContext ac = getCurrentAccessibleContext();
3724                 if (ac instanceof AccessibleComponent) {
3725                     ((AccessibleComponent) ac).requestFocus();
3726                 } else {
3727                     Component c = getCurrentComponent();
3728                     if (c != null) {
3729                         c.requestFocus();
3730                     }
3731                 }
3732             }
3733 
3734             public void addFocusListener(FocusListener l) {
3735                 AccessibleContext ac = getCurrentAccessibleContext();
3736                 if (ac instanceof AccessibleComponent) {
3737                     ((AccessibleComponent) ac).addFocusListener(l);
3738                 } else {
3739                     Component c = getCurrentComponent();
3740                     if (c != null) {
3741                         c.addFocusListener(l);
3742                     }
3743                 }
3744             }
3745 
3746             public void removeFocusListener(FocusListener l) {
3747                 AccessibleContext ac = getCurrentAccessibleContext();
3748                 if (ac instanceof AccessibleComponent) {
3749                     ((AccessibleComponent) ac).removeFocusListener(l);
3750                 } else {
3751                     Component c = getCurrentComponent();
3752                     if (c != null) {
3753                         c.removeFocusListener(l);
3754                     }
3755                 }
3756             }
3757 
3758             // TIGER - 4733624
3759             /**
3760              * Returns the icon for the element renderer, as the only item
3761              * of an array of <code>AccessibleIcon</code>s or a <code>null</code> array
3762              * if the renderer component contains no icons.
3763              *
3764              * @return an array containing the accessible icon
3765              *         or a <code>null</code> array if none
3766              * @since 1.3
3767              */
3768             public AccessibleIcon [] getAccessibleIcon() {
3769                 AccessibleContext ac = getCurrentAccessibleContext();
3770                 if (ac != null) {
3771                     return ac.getAccessibleIcon();
3772                 } else {
3773                     return null;
3774                 }
3775             }
3776 
3777             /**
3778              * {@inheritDoc}
3779              * @implSpec Returns the AccessibleAction for this AccessibleJListChild
3780              * as follows:  First getListCellRendererComponent of the ListCellRenderer
3781              * for the component at the "index in parent" of this child is called.
3782              * Then its AccessibleContext is fetched and that AccessibleContext's
3783              * AccessibleAction is returned.  Note that if an AccessibleAction
3784              * is not found using this process then this object with its implementation
3785              * of the AccessibleAction interface is returned.
3786              * @since 9
3787              */
3788             @Override
3789             public AccessibleAction getAccessibleAction() {
3790                 AccessibleContext ac = getCurrentAccessibleContext();
3791                 if (ac == null) {
3792                     return null;
3793                 } else {
3794                     AccessibleAction aa = ac.getAccessibleAction();
3795                     if (aa != null) {
3796                         return aa;
3797                     } else {
3798                         return this;
3799                     }
3800                 }
3801             }
3802 
3803             /**
3804              * {@inheritDoc}
3805              * @implSpec If i == 0 selects this AccessibleJListChild by calling
3806              * JList.this.setSelectedIndex(indexInParent) and then returns true;
3807              * otherwise returns false.
3808              * @since 9
3809              */
3810             @Override
3811             public boolean doAccessibleAction(int i) {
3812                 if (i == 0) {
3813                     JList.this.setSelectedIndex(indexInParent);
3814                     return true;
3815                 } else {
3816                     return false;
3817                 }
3818             }
3819 
3820             /**
3821              * {@inheritDoc}
3822              * @implSpec If i == 0 returns the action description fetched from
3823              * UIManager.getString("AbstractButton.clickText");
3824              * otherwise returns null.
3825              * @since 9
3826              */
3827             @Override
3828             public String getAccessibleActionDescription(int i) {
3829                 if (i == 0) {
3830                     return UIManager.getString("AbstractButton.clickText");
3831                 } else {
3832                     return null;
3833                 }
3834             }
3835 
3836             /**
3837              * {@inheritDoc}
3838              * @implSpec Returns 1, i.e. there is only one action.
3839              * @since 9
3840              */
3841             @Override
3842             public int getAccessibleActionCount() {
3843                 return 1;
3844             }
3845 
3846         } // inner class AccessibleJListChild
3847 
3848     } // inner class AccessibleJList
3849 }