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         int size = dm.getSize();
2273 
2274         if ((iMin < 0) || (iMax < 0) || (iMin >= size)) {
2275             return new Object[0];
2276         }
2277         iMax = iMax < size ? iMax : size - 1;
2278 
2279         Object[] rvTmp = new Object[1+ (iMax - iMin)];
2280         int n = 0;
2281         for(int i = iMin; i <= iMax; i++) {
2282             if (sm.isSelectedIndex(i)) {
2283                 rvTmp[n++] = dm.getElementAt(i);
2284             }
2285         }
2286         Object[] rv = new Object[n];
2287         System.arraycopy(rvTmp, 0, rv, 0, n);
2288         return rv;
2289     }
2290 
2291     /**
2292      * Returns a list of all the selected items, in increasing order based
2293      * on their indices in the list.
2294      *
2295      * @return the selected items, or an empty list if nothing is selected
2296      * @see #isSelectedIndex
2297      * @see #getModel
2298      * @see #addListSelectionListener
2299      *
2300      * @since 1.7
2301      */
2302     @BeanProperty(bound = false)
2303     public List<E> getSelectedValuesList() {
2304         ListSelectionModel sm = getSelectionModel();
2305         ListModel<E> dm = getModel();
2306 
2307         int iMin = sm.getMinSelectionIndex();
2308         int iMax = sm.getMaxSelectionIndex();
2309         int size = dm.getSize();
2310 
2311         if ((iMin < 0) || (iMax < 0) || (iMin >= size)) {
2312             return Collections.emptyList();
2313         }
2314         iMax = iMax < size ? iMax : size - 1;
2315 
2316         List<E> selectedItems = new ArrayList<E>();
2317         for(int i = iMin; i <= iMax; i++) {
2318             if (sm.isSelectedIndex(i)) {
2319                 selectedItems.add(dm.getElementAt(i));
2320             }
2321         }
2322         return selectedItems;
2323     }
2324 
2325 
2326     /**
2327      * Returns the smallest selected cell index; <i>the selection</i> when only
2328      * a single item is selected in the list. When multiple items are selected,
2329      * it is simply the smallest selected index. Returns {@code -1} if there is
2330      * no selection.
2331      * <p>
2332      * This method is a cover that delegates to {@code getMinSelectionIndex}.
2333      *
2334      * @return the smallest selected cell index
2335      * @see #getMinSelectionIndex
2336      * @see #addListSelectionListener
2337      */
2338     public int getSelectedIndex() {
2339         return getMinSelectionIndex();
2340     }
2341 
2342 
2343     /**
2344      * Returns the value for the smallest selected cell index;
2345      * <i>the selected value</i> when only a single item is selected in the
2346      * list. When multiple items are selected, it is simply the value for the
2347      * smallest selected index. Returns {@code null} if there is no selection.
2348      * <p>
2349      * This is a convenience method that simply returns the model value for
2350      * {@code getMinSelectionIndex}.
2351      *
2352      * @return the first selected value
2353      * @see #getMinSelectionIndex
2354      * @see #getModel
2355      * @see #addListSelectionListener
2356      */
2357     @BeanProperty(bound = false)
2358     public E getSelectedValue() {
2359         int i = getMinSelectionIndex();
2360         return ((i == -1) || (i >= getModel().getSize())) ? null :
2361                 getModel().getElementAt(i);
2362     }
2363 
2364 
2365     /**
2366      * Selects the specified object from the list.
2367      * If the object passed is {@code null}, the selection is cleared.
2368      *
2369      * @param anObject      the object to select
2370      * @param shouldScroll  {@code true} if the list should scroll to display
2371      *                      the selected object, if one exists; otherwise {@code false}
2372      */
2373     public void setSelectedValue(Object anObject,boolean shouldScroll) {
2374         if(anObject == null)
2375             clearSelection();
2376         else if(!anObject.equals(getSelectedValue())) {
2377             int i,c;
2378             ListModel<E> dm = getModel();
2379             for(i=0,c=dm.getSize();i<c;i++)
2380                 if(anObject.equals(dm.getElementAt(i))){
2381                     setSelectedIndex(i);
2382                     if(shouldScroll)
2383                         ensureIndexIsVisible(i);
2384                     repaint();  /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
2385                     return;
2386                 }
2387             setSelectedIndex(-1);
2388         }
2389         repaint(); /** FIX-ME setSelectedIndex does not redraw all the time with the basic l&f**/
2390     }
2391 
2392 
2393 
2394     /**
2395      * --- The Scrollable Implementation ---
2396      */
2397 
2398     private void checkScrollableParameters(Rectangle visibleRect, int orientation) {
2399         if (visibleRect == null) {
2400             throw new IllegalArgumentException("visibleRect must be non-null");
2401         }
2402         switch (orientation) {
2403         case SwingConstants.VERTICAL:
2404         case SwingConstants.HORIZONTAL:
2405             break;
2406         default:
2407             throw new IllegalArgumentException("orientation must be one of: VERTICAL, HORIZONTAL");
2408         }
2409     }
2410 
2411 
2412     /**
2413      * Computes the size of viewport needed to display {@code visibleRowCount}
2414      * rows. The value returned by this method depends on the layout
2415      * orientation:
2416      * <p>
2417      * <b>{@code VERTICAL}:</b>
2418      * <br>
2419      * This is trivial if both {@code fixedCellWidth} and {@code fixedCellHeight}
2420      * have been set (either explicitly or by specifying a prototype cell value).
2421      * The width is simply the {@code fixedCellWidth} plus the list's horizontal
2422      * insets. The height is the {@code fixedCellHeight} multiplied by the
2423      * {@code visibleRowCount}, plus the list's vertical insets.
2424      * <p>
2425      * If either {@code fixedCellWidth} or {@code fixedCellHeight} haven't been
2426      * specified, heuristics are used. If the model is empty, the width is
2427      * the {@code fixedCellWidth}, if greater than {@code 0}, or a hard-coded
2428      * value of {@code 256}. The height is the {@code fixedCellHeight} multiplied
2429      * by {@code visibleRowCount}, if {@code fixedCellHeight} is greater than
2430      * {@code 0}, otherwise it is a hard-coded value of {@code 16} multiplied by
2431      * {@code visibleRowCount}.
2432      * <p>
2433      * If the model isn't empty, the width is the preferred size's width,
2434      * typically the width of the widest list element. The height is the
2435      * height of the cell with index 0 multiplied by the {@code visibleRowCount},
2436      * plus the list's vertical insets.
2437      * <p>
2438      * <b>{@code VERTICAL_WRAP} or {@code HORIZONTAL_WRAP}:</b>
2439      * <br>
2440      * This method simply returns the value from {@code getPreferredSize}.
2441      * The list's {@code ListUI} is expected to override {@code getPreferredSize}
2442      * to return an appropriate value.
2443      *
2444      * @return a dimension containing the size of the viewport needed
2445      *          to display {@code visibleRowCount} rows
2446      * @see #getPreferredScrollableViewportSize
2447      * @see #setPrototypeCellValue
2448      */
2449     @BeanProperty(bound = false)
2450     public Dimension getPreferredScrollableViewportSize()
2451     {
2452         if (getLayoutOrientation() != VERTICAL) {
2453             return getPreferredSize();
2454         }
2455         Insets insets = getInsets();
2456         int dx = insets.left + insets.right;
2457         int dy = insets.top + insets.bottom;
2458 
2459         int visibleRowCount = getVisibleRowCount();
2460         int fixedCellWidth = getFixedCellWidth();
2461         int fixedCellHeight = getFixedCellHeight();
2462 
2463         if ((fixedCellWidth > 0) && (fixedCellHeight > 0)) {
2464             int width = fixedCellWidth + dx;
2465             int height = (visibleRowCount * fixedCellHeight) + dy;
2466             return new Dimension(width, height);
2467         }
2468         else if (getModel().getSize() > 0) {
2469             int width = getPreferredSize().width;
2470             int height;
2471             Rectangle r = getCellBounds(0, 0);
2472             if (r != null) {
2473                 height = (visibleRowCount * r.height) + dy;
2474             }
2475             else {
2476                 // Will only happen if UI null, shouldn't matter what we return
2477                 height = 1;
2478             }
2479             return new Dimension(width, height);
2480         }
2481         else {
2482             fixedCellWidth = (fixedCellWidth > 0) ? fixedCellWidth : 256;
2483             fixedCellHeight = (fixedCellHeight > 0) ? fixedCellHeight : 16;
2484             return new Dimension(fixedCellWidth, fixedCellHeight * visibleRowCount);
2485         }
2486     }
2487 
2488 
2489     /**
2490      * Returns the distance to scroll to expose the next or previous
2491      * row (for vertical scrolling) or column (for horizontal scrolling).
2492      * <p>
2493      * For horizontal scrolling, if the layout orientation is {@code VERTICAL},
2494      * then the list's font size is returned (or {@code 1} if the font is
2495      * {@code null}).
2496      *
2497      * @param visibleRect the view area visible within the viewport
2498      * @param orientation {@code SwingConstants.HORIZONTAL} or
2499      *                    {@code SwingConstants.VERTICAL}
2500      * @param direction less or equal to zero to scroll up/back,
2501      *                  greater than zero for down/forward
2502      * @return the "unit" increment for scrolling in the specified direction;
2503      *         always positive
2504      * @see #getScrollableBlockIncrement
2505      * @see Scrollable#getScrollableUnitIncrement
2506      * @throws IllegalArgumentException if {@code visibleRect} is {@code null}, or
2507      *         {@code orientation} isn't one of {@code SwingConstants.VERTICAL} or
2508      *         {@code SwingConstants.HORIZONTAL}
2509      */
2510     public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)
2511     {
2512         checkScrollableParameters(visibleRect, orientation);
2513 
2514         if (orientation == SwingConstants.VERTICAL) {
2515             int row = locationToIndex(visibleRect.getLocation());
2516 
2517             if (row == -1) {
2518                 return 0;
2519             }
2520             else {
2521                 /* Scroll Down */
2522                 if (direction > 0) {
2523                     Rectangle r = getCellBounds(row, row);
2524                     return (r == null) ? 0 : r.height - (visibleRect.y - r.y);
2525                 }
2526                 /* Scroll Up */
2527                 else {
2528                     Rectangle r = getCellBounds(row, row);
2529 
2530                     /* The first row is completely visible and it's row 0.
2531                      * We're done.
2532                      */
2533                     if ((r.y == visibleRect.y) && (row == 0))  {
2534                         return 0;
2535                     }
2536                     /* The first row is completely visible, return the
2537                      * height of the previous row or 0 if the first row
2538                      * is the top row of the list.
2539                      */
2540                     else if (r.y == visibleRect.y) {
2541                         Point loc = r.getLocation();
2542                         loc.y--;
2543                         int prevIndex = locationToIndex(loc);
2544                         Rectangle prevR = getCellBounds(prevIndex, prevIndex);
2545 
2546                         if (prevR == null || prevR.y >= r.y) {
2547                             return 0;
2548                         }
2549                         return prevR.height;
2550                     }
2551                     /* The first row is partially visible, return the
2552                      * height of hidden part.
2553                      */
2554                     else {
2555                         return visibleRect.y - r.y;
2556                     }
2557                 }
2558             }
2559         } else if (orientation == SwingConstants.HORIZONTAL &&
2560                            getLayoutOrientation() != JList.VERTICAL) {
2561             boolean leftToRight = getComponentOrientation().isLeftToRight();
2562             int index;
2563             Point leadingPoint;
2564 
2565             if (leftToRight) {
2566                 leadingPoint = visibleRect.getLocation();
2567             }
2568             else {
2569                 leadingPoint = new Point(visibleRect.x + visibleRect.width -1,
2570                                          visibleRect.y);
2571             }
2572             index = locationToIndex(leadingPoint);
2573 
2574             if (index != -1) {
2575                 Rectangle cellBounds = getCellBounds(index, index);
2576                 if (cellBounds != null && cellBounds.contains(leadingPoint)) {
2577                     int leadingVisibleEdge;
2578                     int leadingCellEdge;
2579 
2580                     if (leftToRight) {
2581                         leadingVisibleEdge = visibleRect.x;
2582                         leadingCellEdge = cellBounds.x;
2583                     }
2584                     else {
2585                         leadingVisibleEdge = visibleRect.x + visibleRect.width;
2586                         leadingCellEdge = cellBounds.x + cellBounds.width;
2587                     }
2588 
2589                     if (leadingCellEdge != leadingVisibleEdge) {
2590                         if (direction < 0) {
2591                             // Show remainder of leading cell
2592                             return Math.abs(leadingVisibleEdge - leadingCellEdge);
2593 
2594                         }
2595                         else if (leftToRight) {
2596                             // Hide rest of leading cell
2597                             return leadingCellEdge + cellBounds.width - leadingVisibleEdge;
2598                         }
2599                         else {
2600                             // Hide rest of leading cell
2601                             return leadingVisibleEdge - cellBounds.x;
2602                         }
2603                     }
2604                     // ASSUME: All cells are the same width
2605                     return cellBounds.width;
2606                 }
2607             }
2608         }
2609         Font f = getFont();
2610         return (f != null) ? f.getSize() : 1;
2611     }
2612 
2613 
2614     /**
2615      * Returns the distance to scroll to expose the next or previous block.
2616      * <p>
2617      * For vertical scrolling, the following rules are used:
2618      * <ul>
2619      * <li>if scrolling down, returns the distance to scroll so that the last
2620      * visible element becomes the first completely visible element
2621      * <li>if scrolling up, returns the distance to scroll so that the first
2622      * visible element becomes the last completely visible element
2623      * <li>returns {@code visibleRect.height} if the list is empty
2624      * </ul>
2625      * <p>
2626      * For horizontal scrolling, when the layout orientation is either
2627      * {@code VERTICAL_WRAP} or {@code HORIZONTAL_WRAP}:
2628      * <ul>
2629      * <li>if scrolling right, returns the distance to scroll so that the
2630      * last visible element becomes
2631      * the first completely visible element
2632      * <li>if scrolling left, returns the distance to scroll so that the first
2633      * visible element becomes the last completely visible element
2634      * <li>returns {@code visibleRect.width} if the list is empty
2635      * </ul>
2636      * <p>
2637      * For horizontal scrolling and {@code VERTICAL} orientation,
2638      * returns {@code visibleRect.width}.
2639      * <p>
2640      * Note that the value of {@code visibleRect} must be the equal to
2641      * {@code this.getVisibleRect()}.
2642      *
2643      * @param visibleRect the view area visible within the viewport
2644      * @param orientation {@code SwingConstants.HORIZONTAL} or
2645      *                    {@code SwingConstants.VERTICAL}
2646      * @param direction less or equal to zero to scroll up/back,
2647      *                  greater than zero for down/forward
2648      * @return the "block" increment for scrolling in the specified direction;
2649      *         always positive
2650      * @see #getScrollableUnitIncrement
2651      * @see Scrollable#getScrollableBlockIncrement
2652      * @throws IllegalArgumentException if {@code visibleRect} is {@code null}, or
2653      *         {@code orientation} isn't one of {@code SwingConstants.VERTICAL} or
2654      *         {@code SwingConstants.HORIZONTAL}
2655      */
2656     public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
2657         checkScrollableParameters(visibleRect, orientation);
2658         if (orientation == SwingConstants.VERTICAL) {
2659             int inc = visibleRect.height;
2660             /* Scroll Down */
2661             if (direction > 0) {
2662                 // last cell is the lowest left cell
2663                 int last = locationToIndex(new Point(visibleRect.x, visibleRect.y+visibleRect.height-1));
2664                 if (last != -1) {
2665                     Rectangle lastRect = getCellBounds(last,last);
2666                     if (lastRect != null) {
2667                         inc = lastRect.y - visibleRect.y;
2668                         if ( (inc == 0) && (last < getModel().getSize()-1) ) {
2669                             inc = lastRect.height;
2670                         }
2671                     }
2672                 }
2673             }
2674             /* Scroll Up */
2675             else {
2676                 int newFirst = locationToIndex(new Point(visibleRect.x, visibleRect.y-visibleRect.height));
2677                 int first = getFirstVisibleIndex();
2678                 if (newFirst != -1) {
2679                     if (first == -1) {
2680                         first = locationToIndex(visibleRect.getLocation());
2681                     }
2682                     Rectangle newFirstRect = getCellBounds(newFirst,newFirst);
2683                     Rectangle firstRect = getCellBounds(first,first);
2684                     if ((newFirstRect != null) && (firstRect!=null)) {
2685                         while ( (newFirstRect.y + visibleRect.height <
2686                                  firstRect.y + firstRect.height) &&
2687                                 (newFirstRect.y < firstRect.y) ) {
2688                             newFirst++;
2689                             newFirstRect = getCellBounds(newFirst,newFirst);
2690                         }
2691                         inc = visibleRect.y - newFirstRect.y;
2692                         if ( (inc <= 0) && (newFirstRect.y > 0)) {
2693                             newFirst--;
2694                             newFirstRect = getCellBounds(newFirst,newFirst);
2695                             if (newFirstRect != null) {
2696                                 inc = visibleRect.y - newFirstRect.y;
2697                             }
2698                         }
2699                     }
2700                 }
2701             }
2702             return inc;
2703         }
2704         else if (orientation == SwingConstants.HORIZONTAL &&
2705                  getLayoutOrientation() != JList.VERTICAL) {
2706             boolean leftToRight = getComponentOrientation().isLeftToRight();
2707             int inc = visibleRect.width;
2708             /* Scroll Right (in ltr mode) or Scroll Left (in rtl mode) */
2709             if (direction > 0) {
2710                 // position is upper right if ltr, or upper left otherwise
2711                 int x = visibleRect.x + (leftToRight ? (visibleRect.width - 1) : 0);
2712                 int last = locationToIndex(new Point(x, visibleRect.y));
2713 
2714                 if (last != -1) {
2715                     Rectangle lastRect = getCellBounds(last,last);
2716                     if (lastRect != null) {
2717                         if (leftToRight) {
2718                             inc = lastRect.x - visibleRect.x;
2719                         } else {
2720                             inc = visibleRect.x + visibleRect.width
2721                                       - (lastRect.x + lastRect.width);
2722                         }
2723                         if (inc < 0) {
2724                             inc += lastRect.width;
2725                         } else if ( (inc == 0) && (last < getModel().getSize()-1) ) {
2726                             inc = lastRect.width;
2727                         }
2728                     }
2729                 }
2730             }
2731             /* Scroll Left (in ltr mode) or Scroll Right (in rtl mode) */
2732             else {
2733                 // position is upper left corner of the visibleRect shifted
2734                 // left by the visibleRect.width if ltr, or upper right shifted
2735                 // right by the visibleRect.width otherwise
2736                 int x = visibleRect.x + (leftToRight
2737                                          ? -visibleRect.width
2738                                          : visibleRect.width - 1 + visibleRect.width);
2739                 int first = locationToIndex(new Point(x, visibleRect.y));
2740 
2741                 if (first != -1) {
2742                     Rectangle firstRect = getCellBounds(first,first);
2743                     if (firstRect != null) {
2744                         // the right of the first cell
2745                         int firstRight = firstRect.x + firstRect.width;
2746 
2747                         if (leftToRight) {
2748                             if ((firstRect.x < visibleRect.x - visibleRect.width)
2749                                     && (firstRight < visibleRect.x)) {
2750                                 inc = visibleRect.x - firstRight;
2751                             } else {
2752                                 inc = visibleRect.x - firstRect.x;
2753                             }
2754                         } else {
2755                             int visibleRight = visibleRect.x + visibleRect.width;
2756 
2757                             if ((firstRight > visibleRight + visibleRect.width)
2758                                     && (firstRect.x > visibleRight)) {
2759                                 inc = firstRect.x - visibleRight;
2760                             } else {
2761                                 inc = firstRight - visibleRight;
2762                             }
2763                         }
2764                     }
2765                 }
2766             }
2767             return inc;
2768         }
2769         return visibleRect.width;
2770     }
2771 
2772 
2773     /**
2774      * Returns {@code true} if this {@code JList} is displayed in a
2775      * {@code JViewport} and the viewport is wider than the list's
2776      * preferred width, or if the layout orientation is {@code HORIZONTAL_WRAP}
2777      * and {@code visibleRowCount <= 0}; otherwise returns {@code false}.
2778      * <p>
2779      * If {@code false}, then don't track the viewport's width. This allows
2780      * horizontal scrolling if the {@code JViewport} is itself embedded in a
2781      * {@code JScrollPane}.
2782      *
2783      * @return whether or not an enclosing viewport should force the list's
2784      *         width to match its own
2785      * @see Scrollable#getScrollableTracksViewportWidth
2786      */
2787     @BeanProperty(bound = false)
2788     public boolean getScrollableTracksViewportWidth() {
2789         if (getLayoutOrientation() == HORIZONTAL_WRAP &&
2790                                       getVisibleRowCount() <= 0) {
2791             return true;
2792         }
2793         Container parent = SwingUtilities.getUnwrappedParent(this);
2794         if (parent instanceof JViewport) {
2795             return parent.getWidth() > getPreferredSize().width;
2796         }
2797         return false;
2798     }
2799 
2800     /**
2801      * Returns {@code true} if this {@code JList} is displayed in a
2802      * {@code JViewport} and the viewport is taller than the list's
2803      * preferred height, or if the layout orientation is {@code VERTICAL_WRAP}
2804      * and {@code visibleRowCount <= 0}; otherwise returns {@code false}.
2805      * <p>
2806      * If {@code false}, then don't track the viewport's height. This allows
2807      * vertical scrolling if the {@code JViewport} is itself embedded in a
2808      * {@code JScrollPane}.
2809      *
2810      * @return whether or not an enclosing viewport should force the list's
2811      *         height to match its own
2812      * @see Scrollable#getScrollableTracksViewportHeight
2813      */
2814     @BeanProperty(bound = false)
2815     public boolean getScrollableTracksViewportHeight() {
2816         if (getLayoutOrientation() == VERTICAL_WRAP &&
2817                      getVisibleRowCount() <= 0) {
2818             return true;
2819         }
2820         Container parent = SwingUtilities.getUnwrappedParent(this);
2821         if (parent instanceof JViewport) {
2822             return parent.getHeight() > getPreferredSize().height;
2823         }
2824         return false;
2825     }
2826 
2827 
2828     /*
2829      * See {@code readObject} and {@code writeObject} in {@code JComponent}
2830      * for more information about serialization in Swing.
2831      */
2832     private void writeObject(ObjectOutputStream s) throws IOException {
2833         s.defaultWriteObject();
2834         if (getUIClassID().equals(uiClassID)) {
2835             byte count = JComponent.getWriteObjCounter(this);
2836             JComponent.setWriteObjCounter(this, --count);
2837             if (count == 0 && ui != null) {
2838                 ui.installUI(this);
2839             }
2840         }
2841     }
2842 
2843 
2844     /**
2845      * Returns a {@code String} representation of this {@code JList}.
2846      * This method is intended to be used only for debugging purposes,
2847      * and the content and format of the returned {@code String} may vary
2848      * between implementations. The returned {@code String} may be empty,
2849      * but may not be {@code null}.
2850      *
2851      * @return  a {@code String} representation of this {@code JList}.
2852      */
2853     protected String paramString() {
2854         String selectionForegroundString = (selectionForeground != null ?
2855                                             selectionForeground.toString() :
2856                                             "");
2857         String selectionBackgroundString = (selectionBackground != null ?
2858                                             selectionBackground.toString() :
2859                                             "");
2860 
2861         return super.paramString() +
2862         ",fixedCellHeight=" + fixedCellHeight +
2863         ",fixedCellWidth=" + fixedCellWidth +
2864         ",horizontalScrollIncrement=" + horizontalScrollIncrement +
2865         ",selectionBackground=" + selectionBackgroundString +
2866         ",selectionForeground=" + selectionForegroundString +
2867         ",visibleRowCount=" + visibleRowCount +
2868         ",layoutOrientation=" + layoutOrientation;
2869     }
2870 
2871 
2872     /**
2873      * --- Accessibility Support ---
2874      */
2875 
2876     /**
2877      * Gets the {@code AccessibleContext} associated with this {@code JList}.
2878      * For {@code JList}, the {@code AccessibleContext} takes the form of an
2879      * {@code AccessibleJList}.
2880      * <p>
2881      * A new {@code AccessibleJList} instance is created if necessary.
2882      *
2883      * @return an {@code AccessibleJList} that serves as the
2884      *         {@code AccessibleContext} of this {@code JList}
2885      */
2886     @BeanProperty(bound = false)
2887     public AccessibleContext getAccessibleContext() {
2888         if (accessibleContext == null) {
2889             accessibleContext = new AccessibleJList();
2890         }
2891         return accessibleContext;
2892     }
2893 
2894     /**
2895      * This class implements accessibility support for the
2896      * {@code JList} class. It provides an implementation of the
2897      * Java Accessibility API appropriate to list user-interface
2898      * elements.
2899      * <p>
2900      * <strong>Warning:</strong>
2901      * Serialized objects of this class will not be compatible with
2902      * future Swing releases. The current serialization support is
2903      * appropriate for short term storage or RMI between applications running
2904      * the same version of Swing.  As of 1.4, support for long term storage
2905      * of all JavaBeans&trade;
2906      * has been added to the <code>java.beans</code> package.
2907      * Please see {@link java.beans.XMLEncoder}.
2908      */
2909     @SuppressWarnings("serial") // Same-version serialization only
2910     protected class AccessibleJList extends AccessibleJComponent
2911         implements AccessibleSelection, PropertyChangeListener,
2912         ListSelectionListener, ListDataListener {
2913 
2914         int leadSelectionIndex;
2915 
2916         /**
2917          * Constructs an {@code AccessibleJList}.
2918          */
2919         public AccessibleJList() {
2920             super();
2921             JList.this.addPropertyChangeListener(this);
2922             JList.this.getSelectionModel().addListSelectionListener(this);
2923             JList.this.getModel().addListDataListener(this);
2924             leadSelectionIndex = JList.this.getLeadSelectionIndex();
2925         }
2926 
2927         /**
2928          * Property Change Listener change method. Used to track changes
2929          * to the DataModel and ListSelectionModel, in order to re-set
2930          * listeners to those for reporting changes there via the Accessibility
2931          * PropertyChange mechanism.
2932          *
2933          * @param e PropertyChangeEvent
2934          */
2935         public void propertyChange(PropertyChangeEvent e) {
2936             String name = e.getPropertyName();
2937             Object oldValue = e.getOldValue();
2938             Object newValue = e.getNewValue();
2939 
2940                 // re-set listData listeners
2941             if (name.compareTo("model") == 0) {
2942 
2943                 if (oldValue != null && oldValue instanceof ListModel) {
2944                     ((ListModel) oldValue).removeListDataListener(this);
2945                 }
2946                 if (newValue != null && newValue instanceof ListModel) {
2947                     ((ListModel) newValue).addListDataListener(this);
2948                 }
2949 
2950                 // re-set listSelectionModel listeners
2951             } else if (name.compareTo("selectionModel") == 0) {
2952 
2953                 if (oldValue != null && oldValue instanceof ListSelectionModel) {
2954                     ((ListSelectionModel) oldValue).removeListSelectionListener(this);
2955                 }
2956                 if (newValue != null && newValue instanceof ListSelectionModel) {
2957                     ((ListSelectionModel) newValue).addListSelectionListener(this);
2958                 }
2959 
2960                 firePropertyChange(
2961                     AccessibleContext.ACCESSIBLE_SELECTION_PROPERTY,
2962                     Boolean.valueOf(false), Boolean.valueOf(true));
2963             }
2964         }
2965 
2966         /**
2967          * List Selection Listener value change method. Used to fire
2968          * the property change
2969          *
2970          * @param e ListSelectionEvent
2971          *
2972          */
2973         public void valueChanged(ListSelectionEvent e) {
2974             int oldLeadSelectionIndex = leadSelectionIndex;
2975             leadSelectionIndex = JList.this.getLeadSelectionIndex();
2976             if (oldLeadSelectionIndex != leadSelectionIndex) {
2977                 Accessible oldLS, newLS;
2978                 oldLS = (oldLeadSelectionIndex >= 0)
2979                         ? getAccessibleChild(oldLeadSelectionIndex)
2980                         : null;
2981                 newLS = (leadSelectionIndex >= 0)
2982                         ? getAccessibleChild(leadSelectionIndex)
2983                         : null;
2984                 firePropertyChange(AccessibleContext.ACCESSIBLE_ACTIVE_DESCENDANT_PROPERTY,
2985                                    oldLS, newLS);
2986             }
2987 
2988             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
2989                                Boolean.valueOf(false), Boolean.valueOf(true));
2990             firePropertyChange(AccessibleContext.ACCESSIBLE_SELECTION_PROPERTY,
2991                                Boolean.valueOf(false), Boolean.valueOf(true));
2992 
2993             // Process the State changes for Multiselectable
2994             AccessibleStateSet s = getAccessibleStateSet();
2995             ListSelectionModel lsm = JList.this.getSelectionModel();
2996             if (lsm.getSelectionMode() != ListSelectionModel.SINGLE_SELECTION) {
2997                 if (!s.contains(AccessibleState.MULTISELECTABLE)) {
2998                     s.add(AccessibleState.MULTISELECTABLE);
2999                     firePropertyChange(AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
3000                                        null, AccessibleState.MULTISELECTABLE);
3001                 }
3002             } else {
3003                 if (s.contains(AccessibleState.MULTISELECTABLE)) {
3004                     s.remove(AccessibleState.MULTISELECTABLE);
3005                     firePropertyChange(AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
3006                                        AccessibleState.MULTISELECTABLE, null);
3007                 }
3008             }
3009         }
3010 
3011         /**
3012          * List Data Listener interval added method. Used to fire the visible data property change
3013          *
3014          * @param e ListDataEvent
3015          *
3016          */
3017         public void intervalAdded(ListDataEvent e) {
3018             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3019                                Boolean.valueOf(false), Boolean.valueOf(true));
3020         }
3021 
3022         /**
3023          * List Data Listener interval removed method. Used to fire the visible data property change
3024          *
3025          * @param e ListDataEvent
3026          *
3027          */
3028         public void intervalRemoved(ListDataEvent e) {
3029             firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3030                                Boolean.valueOf(false), Boolean.valueOf(true));
3031         }
3032 
3033         /**
3034          * List Data Listener contents changed method. Used to fire the visible data property change
3035          *
3036          * @param e ListDataEvent
3037          *
3038          */
3039          public void contentsChanged(ListDataEvent e) {
3040              firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY,
3041                                 Boolean.valueOf(false), Boolean.valueOf(true));
3042          }
3043 
3044     // AccessibleContext methods
3045 
3046         /**
3047          * Get the state set of this object.
3048          *
3049          * @return an instance of AccessibleState containing the current state
3050          * of the object
3051          * @see AccessibleState
3052          */
3053         public AccessibleStateSet getAccessibleStateSet() {
3054             AccessibleStateSet states = super.getAccessibleStateSet();
3055             if (selectionModel.getSelectionMode() !=
3056                 ListSelectionModel.SINGLE_SELECTION) {
3057                 states.add(AccessibleState.MULTISELECTABLE);
3058             }
3059             return states;
3060         }
3061 
3062         /**
3063          * Get the role of this object.
3064          *
3065          * @return an instance of AccessibleRole describing the role of the
3066          * object
3067          * @see AccessibleRole
3068          */
3069         public AccessibleRole getAccessibleRole() {
3070             return AccessibleRole.LIST;
3071         }
3072 
3073         /**
3074          * Returns the <code>Accessible</code> child contained at
3075          * the local coordinate <code>Point</code>, if one exists.
3076          * Otherwise returns <code>null</code>.
3077          *
3078          * @return the <code>Accessible</code> at the specified
3079          *    location, if it exists
3080          */
3081         public Accessible getAccessibleAt(Point p) {
3082             int i = locationToIndex(p);
3083             if (i >= 0) {
3084                 return new AccessibleJListChild(JList.this, i);
3085             } else {
3086                 return null;
3087             }
3088         }
3089 
3090         /**
3091          * Returns the number of accessible children in the object.  If all
3092          * of the children of this object implement Accessible, than this
3093          * method should return the number of children of this object.
3094          *
3095          * @return the number of accessible children in the object.
3096          */
3097         public int getAccessibleChildrenCount() {
3098             return getModel().getSize();
3099         }
3100 
3101         /**
3102          * Return the nth Accessible child of the object.
3103          *
3104          * @param i zero-based index of child
3105          * @return the nth Accessible child of the object
3106          */
3107         public Accessible getAccessibleChild(int i) {
3108             if (i >= getModel().getSize()) {
3109                 return null;
3110             } else {
3111                 return new AccessibleJListChild(JList.this, i);
3112             }
3113         }
3114 
3115         /**
3116          * Get the AccessibleSelection associated with this object.  In the
3117          * implementation of the Java Accessibility API for this class,
3118          * return this object, which is responsible for implementing the
3119          * AccessibleSelection interface on behalf of itself.
3120          *
3121          * @return this object
3122          */
3123         public AccessibleSelection getAccessibleSelection() {
3124             return this;
3125         }
3126 
3127 
3128     // AccessibleSelection methods
3129 
3130         /**
3131          * Returns the number of items currently selected.
3132          * If no items are selected, the return value will be 0.
3133          *
3134          * @return the number of items currently selected.
3135          */
3136          public int getAccessibleSelectionCount() {
3137              return JList.this.getSelectedIndices().length;
3138          }
3139 
3140         /**
3141          * Returns an Accessible representing the specified selected item
3142          * in the object.  If there isn't a selection, or there are
3143          * fewer items selected than the integer passed in, the return
3144          * value will be <code>null</code>.
3145          *
3146          * @param i the zero-based index of selected items
3147          * @return an Accessible containing the selected item
3148          */
3149          public Accessible getAccessibleSelection(int i) {
3150              int len = getAccessibleSelectionCount();
3151              if (i < 0 || i >= len) {
3152                  return null;
3153              } else {
3154                  return getAccessibleChild(JList.this.getSelectedIndices()[i]);
3155              }
3156          }
3157 
3158         /**
3159          * Returns true if the current child of this object is selected.
3160          *
3161          * @param i the zero-based index of the child in this Accessible
3162          * object.
3163          * @see AccessibleContext#getAccessibleChild
3164          */
3165         public boolean isAccessibleChildSelected(int i) {
3166             return isSelectedIndex(i);
3167         }
3168 
3169         /**
3170          * Adds the specified selected item in the object to the object's
3171          * selection.  If the object supports multiple selections,
3172          * the specified item is added to any existing selection, otherwise
3173          * it replaces any existing selection in the object.  If the
3174          * specified item is already selected, this method has no effect.
3175          *
3176          * @param i the zero-based index of selectable items
3177          */
3178          public void addAccessibleSelection(int i) {
3179              JList.this.addSelectionInterval(i, i);
3180          }
3181 
3182         /**
3183          * Removes the specified selected item in the object from the object's
3184          * selection.  If the specified item isn't currently selected, this
3185          * method has no effect.
3186          *
3187          * @param i the zero-based index of selectable items
3188          */
3189          public void removeAccessibleSelection(int i) {
3190              JList.this.removeSelectionInterval(i, i);
3191          }
3192 
3193         /**
3194          * Clears the selection in the object, so that nothing in the
3195          * object is selected.
3196          */
3197          public void clearAccessibleSelection() {
3198              JList.this.clearSelection();
3199          }
3200 
3201         /**
3202          * Causes every selected item in the object to be selected
3203          * if the object supports multiple selections.
3204          */
3205          public void selectAllAccessibleSelection() {
3206              JList.this.addSelectionInterval(0, getAccessibleChildrenCount() -1);
3207          }
3208 
3209           /**
3210            * This class implements accessibility support appropriate
3211            * for list children.
3212            */
3213         protected class AccessibleJListChild extends AccessibleContext
3214                 implements Accessible, AccessibleComponent, AccessibleAction {
3215             private JList<E>     parent = null;
3216             int indexInParent;
3217             private Component component = null;
3218             private AccessibleContext accessibleContext = null;
3219             private ListModel<E> listModel;
3220             private ListCellRenderer<? super E> cellRenderer = null;
3221 
3222             /**
3223              * Constructs an {@code AccessibleJListChild}.
3224              * @param parent the parent
3225              * @param indexInParent the index in the parent
3226              */
3227             public AccessibleJListChild(JList<E> parent, int indexInParent) {
3228                 this.parent = parent;
3229                 this.setAccessibleParent(parent);
3230                 this.indexInParent = indexInParent;
3231                 if (parent != null) {
3232                     listModel = parent.getModel();
3233                     cellRenderer = parent.getCellRenderer();
3234                 }
3235             }
3236 
3237             private Component getCurrentComponent() {
3238                 return getComponentAtIndex(indexInParent);
3239             }
3240 
3241             AccessibleContext getCurrentAccessibleContext() {
3242                 Component c = getComponentAtIndex(indexInParent);
3243                 if (c instanceof Accessible) {
3244                     return c.getAccessibleContext();
3245                 } else {
3246                     return null;
3247                 }
3248             }
3249 
3250             private Component getComponentAtIndex(int index) {
3251                 if (index < 0 || index >= listModel.getSize()) {
3252                     return null;
3253                 }
3254                 if ((parent != null)
3255                         && (listModel != null)
3256                         && cellRenderer != null) {
3257                     E value = listModel.getElementAt(index);
3258                     boolean isSelected = parent.isSelectedIndex(index);
3259                     boolean isFocussed = parent.isFocusOwner()
3260                             && (index == parent.getLeadSelectionIndex());
3261                     return cellRenderer.getListCellRendererComponent(
3262                             parent,
3263                             value,
3264                             index,
3265                             isSelected,
3266                             isFocussed);
3267                 } else {
3268                     return null;
3269                 }
3270             }
3271 
3272 
3273             // Accessible Methods
3274            /**
3275             * Get the AccessibleContext for this object. In the
3276             * implementation of the Java Accessibility API for this class,
3277             * returns this object, which is its own AccessibleContext.
3278             *
3279             * @return this object
3280             */
3281             public AccessibleContext getAccessibleContext() {
3282                 return this;
3283             }
3284 
3285 
3286             // AccessibleContext methods
3287 
3288             public String getAccessibleName() {
3289                 AccessibleContext ac = getCurrentAccessibleContext();
3290                 if (ac != null) {
3291                     return ac.getAccessibleName();
3292                 } else {
3293                     return null;
3294                 }
3295             }
3296 
3297             public void setAccessibleName(String s) {
3298                 AccessibleContext ac = getCurrentAccessibleContext();
3299                 if (ac != null) {
3300                     ac.setAccessibleName(s);
3301                 }
3302             }
3303 
3304             public String getAccessibleDescription() {
3305                 AccessibleContext ac = getCurrentAccessibleContext();
3306                 if (ac != null) {
3307                     return ac.getAccessibleDescription();
3308                 } else {
3309                     return null;
3310                 }
3311             }
3312 
3313             public void setAccessibleDescription(String s) {
3314                 AccessibleContext ac = getCurrentAccessibleContext();
3315                 if (ac != null) {
3316                     ac.setAccessibleDescription(s);
3317                 }
3318             }
3319 
3320             public AccessibleRole getAccessibleRole() {
3321                 AccessibleContext ac = getCurrentAccessibleContext();
3322                 if (ac != null) {
3323                     return ac.getAccessibleRole();
3324                 } else {
3325                     return null;
3326                 }
3327             }
3328 
3329             public AccessibleStateSet getAccessibleStateSet() {
3330                 AccessibleContext ac = getCurrentAccessibleContext();
3331                 AccessibleStateSet s;
3332                 if (ac != null) {
3333                     s = ac.getAccessibleStateSet();
3334                 } else {
3335                     s = new AccessibleStateSet();
3336                 }
3337 
3338                 s.add(AccessibleState.SELECTABLE);
3339                 if (parent.isFocusOwner()
3340                     && (indexInParent == parent.getLeadSelectionIndex())) {
3341                     s.add(AccessibleState.ACTIVE);
3342                 }
3343                 if (parent.isSelectedIndex(indexInParent)) {
3344                     s.add(AccessibleState.SELECTED);
3345                 }
3346                 if (this.isShowing()) {
3347                     s.add(AccessibleState.SHOWING);
3348                 } else if (s.contains(AccessibleState.SHOWING)) {
3349                     s.remove(AccessibleState.SHOWING);
3350                 }
3351                 if (this.isVisible()) {
3352                     s.add(AccessibleState.VISIBLE);
3353                 } else if (s.contains(AccessibleState.VISIBLE)) {
3354                     s.remove(AccessibleState.VISIBLE);
3355                 }
3356                 s.add(AccessibleState.TRANSIENT); // cell-rendered
3357                 return s;
3358             }
3359 
3360             public int getAccessibleIndexInParent() {
3361                 return indexInParent;
3362             }
3363 
3364             public int getAccessibleChildrenCount() {
3365                 AccessibleContext ac = getCurrentAccessibleContext();
3366                 if (ac != null) {
3367                     return ac.getAccessibleChildrenCount();
3368                 } else {
3369                     return 0;
3370                 }
3371             }
3372 
3373             public Accessible getAccessibleChild(int i) {
3374                 AccessibleContext ac = getCurrentAccessibleContext();
3375                 if (ac != null) {
3376                     Accessible accessibleChild = ac.getAccessibleChild(i);
3377                     ac.setAccessibleParent(this);
3378                     return accessibleChild;
3379                 } else {
3380                     return null;
3381                 }
3382             }
3383 
3384             public Locale getLocale() {
3385                 AccessibleContext ac = getCurrentAccessibleContext();
3386                 if (ac != null) {
3387                     return ac.getLocale();
3388                 } else {
3389                     return null;
3390                 }
3391             }
3392 
3393             public void addPropertyChangeListener(PropertyChangeListener l) {
3394                 AccessibleContext ac = getCurrentAccessibleContext();
3395                 if (ac != null) {
3396                     ac.addPropertyChangeListener(l);
3397                 }
3398             }
3399 
3400             public void removePropertyChangeListener(PropertyChangeListener l) {
3401                 AccessibleContext ac = getCurrentAccessibleContext();
3402                 if (ac != null) {
3403                     ac.removePropertyChangeListener(l);
3404                 }
3405             }
3406 
3407            /**
3408             * Get the AccessibleComponent associated with this object.  In the
3409             * implementation of the Java Accessibility API for this class,
3410             * return this object, which is responsible for implementing the
3411             * AccessibleComponent interface on behalf of itself.
3412             *
3413             * @return this object
3414             */
3415             public AccessibleComponent getAccessibleComponent() {
3416                 return this; // to override getBounds()
3417             }
3418 
3419             public AccessibleSelection getAccessibleSelection() {
3420                 AccessibleContext ac = getCurrentAccessibleContext();
3421                 return ac != null ? ac.getAccessibleSelection() : null;
3422             }
3423 
3424             public AccessibleText getAccessibleText() {
3425                 AccessibleContext ac = getCurrentAccessibleContext();
3426                 return ac != null ? ac.getAccessibleText() : null;
3427             }
3428 
3429             public AccessibleValue getAccessibleValue() {
3430                 AccessibleContext ac = getCurrentAccessibleContext();
3431                 return ac != null ? ac.getAccessibleValue() : null;
3432             }
3433 
3434 
3435             // AccessibleComponent methods
3436 
3437             public Color getBackground() {
3438                 AccessibleContext ac = getCurrentAccessibleContext();
3439                 if (ac instanceof AccessibleComponent) {
3440                     return ((AccessibleComponent) ac).getBackground();
3441                 } else {
3442                     Component c = getCurrentComponent();
3443                     if (c != null) {
3444                         return c.getBackground();
3445                     } else {
3446                         return null;
3447                     }
3448                 }
3449             }
3450 
3451             public void setBackground(Color c) {
3452                 AccessibleContext ac = getCurrentAccessibleContext();
3453                 if (ac instanceof AccessibleComponent) {
3454                     ((AccessibleComponent) ac).setBackground(c);
3455                 } else {
3456                     Component cp = getCurrentComponent();
3457                     if (cp != null) {
3458                         cp.setBackground(c);
3459                     }
3460                 }
3461             }
3462 
3463             public Color getForeground() {
3464                 AccessibleContext ac = getCurrentAccessibleContext();
3465                 if (ac instanceof AccessibleComponent) {
3466                     return ((AccessibleComponent) ac).getForeground();
3467                 } else {
3468                     Component c = getCurrentComponent();
3469                     if (c != null) {
3470                         return c.getForeground();
3471                     } else {
3472                         return null;
3473                     }
3474                 }
3475             }
3476 
3477             public void setForeground(Color c) {
3478                 AccessibleContext ac = getCurrentAccessibleContext();
3479                 if (ac instanceof AccessibleComponent) {
3480                     ((AccessibleComponent) ac).setForeground(c);
3481                 } else {
3482                     Component cp = getCurrentComponent();
3483                     if (cp != null) {
3484                         cp.setForeground(c);
3485                     }
3486                 }
3487             }
3488 
3489             public Cursor getCursor() {
3490                 AccessibleContext ac = getCurrentAccessibleContext();
3491                 if (ac instanceof AccessibleComponent) {
3492                     return ((AccessibleComponent) ac).getCursor();
3493                 } else {
3494                     Component c = getCurrentComponent();
3495                     if (c != null) {
3496                         return c.getCursor();
3497                     } else {
3498                         Accessible ap = getAccessibleParent();
3499                         if (ap instanceof AccessibleComponent) {
3500                             return ((AccessibleComponent) ap).getCursor();
3501                         } else {
3502                             return null;
3503                         }
3504                     }
3505                 }
3506             }
3507 
3508             public void setCursor(Cursor c) {
3509                 AccessibleContext ac = getCurrentAccessibleContext();
3510                 if (ac instanceof AccessibleComponent) {
3511                     ((AccessibleComponent) ac).setCursor(c);
3512                 } else {
3513                     Component cp = getCurrentComponent();
3514                     if (cp != null) {
3515                         cp.setCursor(c);
3516                     }
3517                 }
3518             }
3519 
3520             public Font getFont() {
3521                 AccessibleContext ac = getCurrentAccessibleContext();
3522                 if (ac instanceof AccessibleComponent) {
3523                     return ((AccessibleComponent) ac).getFont();
3524                 } else {
3525                     Component c = getCurrentComponent();
3526                     if (c != null) {
3527                         return c.getFont();
3528                     } else {
3529                         return null;
3530                     }
3531                 }
3532             }
3533 
3534             public void setFont(Font f) {
3535                 AccessibleContext ac = getCurrentAccessibleContext();
3536                 if (ac instanceof AccessibleComponent) {
3537                     ((AccessibleComponent) ac).setFont(f);
3538                 } else {
3539                     Component c = getCurrentComponent();
3540                     if (c != null) {
3541                         c.setFont(f);
3542                     }
3543                 }
3544             }
3545 
3546             public FontMetrics getFontMetrics(Font f) {
3547                 AccessibleContext ac = getCurrentAccessibleContext();
3548                 if (ac instanceof AccessibleComponent) {
3549                     return ((AccessibleComponent) ac).getFontMetrics(f);
3550                 } else {
3551                     Component c = getCurrentComponent();
3552                     if (c != null) {
3553                         return c.getFontMetrics(f);
3554                     } else {
3555                         return null;
3556                     }
3557                 }
3558             }
3559 
3560             public boolean isEnabled() {
3561                 AccessibleContext ac = getCurrentAccessibleContext();
3562                 if (ac instanceof AccessibleComponent) {
3563                     return ((AccessibleComponent) ac).isEnabled();
3564                 } else {
3565                     Component c = getCurrentComponent();
3566                     if (c != null) {
3567                         return c.isEnabled();
3568                     } else {
3569                         return false;
3570                     }
3571                 }
3572             }
3573 
3574             public void setEnabled(boolean b) {
3575                 AccessibleContext ac = getCurrentAccessibleContext();
3576                 if (ac instanceof AccessibleComponent) {
3577                     ((AccessibleComponent) ac).setEnabled(b);
3578                 } else {
3579                     Component c = getCurrentComponent();
3580                     if (c != null) {
3581                         c.setEnabled(b);
3582                     }
3583                 }
3584             }
3585 
3586             public boolean isVisible() {
3587                 int fi = parent.getFirstVisibleIndex();
3588                 int li = parent.getLastVisibleIndex();
3589                 // The UI incorrectly returns a -1 for the last
3590                 // visible index if the list is smaller than the
3591                 // viewport size.
3592                 if (li == -1) {
3593                     li = parent.getModel().getSize() - 1;
3594                 }
3595                 return ((indexInParent >= fi)
3596                         && (indexInParent <= li));
3597             }
3598 
3599             public void setVisible(boolean b) {
3600             }
3601 
3602             public boolean isShowing() {
3603                 return (parent.isShowing() && isVisible());
3604             }
3605 
3606             public boolean contains(Point p) {
3607                 AccessibleContext ac = getCurrentAccessibleContext();
3608                 if (ac instanceof AccessibleComponent) {
3609                     Rectangle r = ((AccessibleComponent) ac).getBounds();
3610                     return r.contains(p);
3611                 } else {
3612                     Component c = getCurrentComponent();
3613                     if (c != null) {
3614                         Rectangle r = c.getBounds();
3615                         return r.contains(p);
3616                     } else {
3617                         return getBounds().contains(p);
3618                     }
3619                 }
3620             }
3621 
3622             public Point getLocationOnScreen() {
3623                 if (parent != null) {
3624                     Point listLocation;
3625                     try {
3626                         listLocation = parent.getLocationOnScreen();
3627                     } catch (IllegalComponentStateException e) {
3628                         // This can happen if the component isn't visisble
3629                         return null;
3630                     }
3631                     Point componentLocation = parent.indexToLocation(indexInParent);
3632                     if (componentLocation != null) {
3633                         componentLocation.translate(listLocation.x, listLocation.y);
3634                         return componentLocation;
3635                     } else {
3636                         return null;
3637                     }
3638                 } else {
3639                     return null;
3640                 }
3641             }
3642 
3643             public Point getLocation() {
3644                 if (parent != null) {
3645                     return parent.indexToLocation(indexInParent);
3646                 } else {
3647                     return null;
3648                 }
3649             }
3650 
3651             public void setLocation(Point p) {
3652                 if ((parent != null)  && (parent.contains(p))) {
3653                     ensureIndexIsVisible(indexInParent);
3654                 }
3655             }
3656 
3657             public Rectangle getBounds() {
3658                 if (parent != null) {
3659                     return parent.getCellBounds(indexInParent,indexInParent);
3660                 } else {
3661                     return null;
3662                 }
3663             }
3664 
3665             public void setBounds(Rectangle r) {
3666                 AccessibleContext ac = getCurrentAccessibleContext();
3667                 if (ac instanceof AccessibleComponent) {
3668                     ((AccessibleComponent) ac).setBounds(r);
3669                 }
3670             }
3671 
3672             public Dimension getSize() {
3673                 Rectangle cellBounds = this.getBounds();
3674                 if (cellBounds != null) {
3675                     return cellBounds.getSize();
3676                 } else {
3677                     return null;
3678                 }
3679             }
3680 
3681             public void setSize (Dimension d) {
3682                 AccessibleContext ac = getCurrentAccessibleContext();
3683                 if (ac instanceof AccessibleComponent) {
3684                     ((AccessibleComponent) ac).setSize(d);
3685                 } else {
3686                     Component c = getCurrentComponent();
3687                     if (c != null) {
3688                         c.setSize(d);
3689                     }
3690                 }
3691             }
3692 
3693             public Accessible getAccessibleAt(Point p) {
3694                 AccessibleContext ac = getCurrentAccessibleContext();
3695                 if (ac instanceof AccessibleComponent) {
3696                     return ((AccessibleComponent) ac).getAccessibleAt(p);
3697                 } else {
3698                     return null;
3699                 }
3700             }
3701 
3702             @SuppressWarnings("deprecation")
3703             public boolean isFocusTraversable() {
3704                 AccessibleContext ac = getCurrentAccessibleContext();
3705                 if (ac instanceof AccessibleComponent) {
3706                     return ((AccessibleComponent) ac).isFocusTraversable();
3707                 } else {
3708                     Component c = getCurrentComponent();
3709                     if (c != null) {
3710                         return c.isFocusTraversable();
3711                     } else {
3712                         return false;
3713                     }
3714                 }
3715             }
3716 
3717             public void requestFocus() {
3718                 AccessibleContext ac = getCurrentAccessibleContext();
3719                 if (ac instanceof AccessibleComponent) {
3720                     ((AccessibleComponent) ac).requestFocus();
3721                 } else {
3722                     Component c = getCurrentComponent();
3723                     if (c != null) {
3724                         c.requestFocus();
3725                     }
3726                 }
3727             }
3728 
3729             public void addFocusListener(FocusListener l) {
3730                 AccessibleContext ac = getCurrentAccessibleContext();
3731                 if (ac instanceof AccessibleComponent) {
3732                     ((AccessibleComponent) ac).addFocusListener(l);
3733                 } else {
3734                     Component c = getCurrentComponent();
3735                     if (c != null) {
3736                         c.addFocusListener(l);
3737                     }
3738                 }
3739             }
3740 
3741             public void removeFocusListener(FocusListener l) {
3742                 AccessibleContext ac = getCurrentAccessibleContext();
3743                 if (ac instanceof AccessibleComponent) {
3744                     ((AccessibleComponent) ac).removeFocusListener(l);
3745                 } else {
3746                     Component c = getCurrentComponent();
3747                     if (c != null) {
3748                         c.removeFocusListener(l);
3749                     }
3750                 }
3751             }
3752 
3753             // TIGER - 4733624
3754             /**
3755              * Returns the icon for the element renderer, as the only item
3756              * of an array of <code>AccessibleIcon</code>s or a <code>null</code> array
3757              * if the renderer component contains no icons.
3758              *
3759              * @return an array containing the accessible icon
3760              *         or a <code>null</code> array if none
3761              * @since 1.3
3762              */
3763             public AccessibleIcon [] getAccessibleIcon() {
3764                 AccessibleContext ac = getCurrentAccessibleContext();
3765                 if (ac != null) {
3766                     return ac.getAccessibleIcon();
3767                 } else {
3768                     return null;
3769                 }
3770             }
3771 
3772             /**
3773              * {@inheritDoc}
3774              * @implSpec Returns the AccessibleAction for this AccessibleJListChild
3775              * as follows:  First getListCellRendererComponent of the ListCellRenderer
3776              * for the component at the "index in parent" of this child is called.
3777              * Then its AccessibleContext is fetched and that AccessibleContext's
3778              * AccessibleAction is returned.  Note that if an AccessibleAction
3779              * is not found using this process then this object with its implementation
3780              * of the AccessibleAction interface is returned.
3781              * @since 9
3782              */
3783             @Override
3784             public AccessibleAction getAccessibleAction() {
3785                 AccessibleContext ac = getCurrentAccessibleContext();
3786                 if (ac == null) {
3787                     return null;
3788                 } else {
3789                     AccessibleAction aa = ac.getAccessibleAction();
3790                     if (aa != null) {
3791                         return aa;
3792                     } else {
3793                         return this;
3794                     }
3795                 }
3796             }
3797 
3798             /**
3799              * {@inheritDoc}
3800              * @implSpec If i == 0 selects this AccessibleJListChild by calling
3801              * JList.this.setSelectedIndex(indexInParent) and then returns true;
3802              * otherwise returns false.
3803              * @since 9
3804              */
3805             @Override
3806             public boolean doAccessibleAction(int i) {
3807                 if (i == 0) {
3808                     JList.this.setSelectedIndex(indexInParent);
3809                     return true;
3810                 } else {
3811                     return false;
3812                 }
3813             }
3814 
3815             /**
3816              * {@inheritDoc}
3817              * @implSpec If i == 0 returns the action description fetched from
3818              * UIManager.getString("AbstractButton.clickText");
3819              * otherwise returns null.
3820              * @since 9
3821              */
3822             @Override
3823             public String getAccessibleActionDescription(int i) {
3824                 if (i == 0) {
3825                     return UIManager.getString("AbstractButton.clickText");
3826                 } else {
3827                     return null;
3828                 }
3829             }
3830 
3831             /**
3832              * {@inheritDoc}
3833              * @implSpec Returns 1, i.e. there is only one action.
3834              * @since 9
3835              */
3836             @Override
3837             public int getAccessibleActionCount() {
3838                 return 1;
3839             }
3840 
3841         } // inner class AccessibleJListChild
3842 
3843     } // inner class AccessibleJList
3844 }