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    9    * by Oracle in the LICENSE file that accompanied this code.
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   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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   25   
   26   package javax.swing.event;
   27   
   28   import java.util.EventObject;
   29   import javax.swing.tree.TreePath;
   30   
   31   
   32   /**
   33    * Encapsulates information describing changes to a tree model, and
   34    * used to notify tree model listeners of the change.
   35    * For more information and examples see
   36    * <a
   37    href="http://java.sun.com/docs/books/tutorial/uiswing/events/treemodellistener.html">How to Write a Tree Model Listener</a>,
   38    * a section in <em>The Java Tutorial.</em>
   39    * <p>
   40    * <strong>Warning:</strong>
   41    * Serialized objects of this class will not be compatible with
   42    * future Swing releases. The current serialization support is
   43    * appropriate for short term storage or RMI between applications running
   44    * the same version of Swing.  As of 1.4, support for long term storage
   45    * of all JavaBeans<sup><font size="-2">TM</font></sup>
   46    * has been added to the <code>java.beans</code> package.
   47    * Please see {@link java.beans.XMLEncoder}.
   48    *
   49    * @author Rob Davis
   50    * @author Ray Ryan
   51    * @author Scott Violet
   52    */
   53   public class TreeModelEvent extends EventObject {
   54       /** Path to the parent of the nodes that have changed. */
   55       protected TreePath  path;
   56       /** Indices identifying the position of where the children were. */
   57       protected int[]     childIndices;
   58       /** Children that have been removed. */
   59       protected Object[]  children;
   60   
   61       /**
   62        * Used to create an event when nodes have been changed, inserted, or
   63        * removed, identifying the path to the parent of the modified items as
   64        * an array of Objects. All of the modified objects are siblings which are
   65        * direct descendents (not grandchildren) of the specified parent.
   66        * The positions at which the inserts, deletes, or changes occurred are
   67        * specified by an array of <code>int</code>. The indexes in that array
   68        * must be in order, from lowest to highest.
   69        * <p>
   70        * For changes, the indexes in the model correspond exactly to the indexes
   71        * of items currently displayed in the UI. As a result, it is not really
   72        * critical if the indexes are not in their exact order. But after multiple
   73        * inserts or deletes, the items currently in the UI no longer correspond
   74        * to the items in the model. It is therefore critical to specify the
   75        * indexes properly for inserts and deletes.
   76        * <p>
   77        * For inserts, the indexes represent the <i>final</i> state of the tree,
   78        * after the inserts have occurred. Since the indexes must be specified in
   79        * order, the most natural processing methodology is to do the inserts
   80        * starting at the lowest index and working towards the highest. Accumulate
   81        * a Vector of <code>Integer</code> objects that specify the
   82        * insert-locations as you go, then convert the Vector to an
   83        * array of <code>int</code> to create the event. When the postition-index
   84        * equals zero, the node is inserted at the beginning of the list. When the
   85        * position index equals the size of the list, the node is "inserted" at
   86        * (appended to) the end of the list.
   87        * <p>
   88        * For deletes, the indexes represent the <i>initial</i> state of the tree,
   89        * before the deletes have occurred. Since the indexes must be specified in
   90        * order, the most natural processing methodology is to use a delete-counter.
   91        * Start by initializing the counter to zero and start work through the
   92        * list from lowest to higest. Every time you do a delete, add the current
   93        * value of the delete-counter to the index-position where the delete occurred,
   94        * and append the result to a Vector of delete-locations, using
   95        * <code>addElement()</code>. Then increment the delete-counter. The index
   96        * positions stored in the Vector therefore reflect the effects of all previous
   97        * deletes, so they represent each object's position in the initial tree.
   98        * (You could also start at the highest index and working back towards the
   99        * lowest, accumulating a Vector of delete-locations as you go using the
  100        * <code>insertElementAt(Integer, 0)</code>.) However you produce the Vector
  101        * of initial-positions, you then need to convert the Vector of <code>Integer</code>
  102        * objects to an array of <code>int</code> to create the event.
  103        * <p>
  104        * <b>Notes:</b><ul>
  105        * <li>Like the <code>insertNodeInto</code> method in the
  106        *    <code>DefaultTreeModel</code> class, <code>insertElementAt</code>
  107        *    appends to the <code>Vector</code> when the index matches the size
  108        *    of the vector. So you can use <code>insertElementAt(Integer, 0)</code>
  109        *    even when the vector is empty.
  110        * <ul>To create a node changed event for the root node, specify the parent
  111        *     and the child indices as <code>null</code>.
  112        * </ul>
  113        *
  114        * @param source the Object responsible for generating the event (typically
  115        *               the creator of the event object passes <code>this</code>
  116        *               for its value)
  117        * @param path   an array of Object identifying the path to the
  118        *               parent of the modified item(s), where the first element
  119        *               of the array is the Object stored at the root node and
  120        *               the last element is the Object stored at the parent node
  121        * @param childIndices an array of <code>int</code> that specifies the
  122        *               index values of the removed items. The indices must be
  123        *               in sorted order, from lowest to highest
  124        * @param children an array of Object containing the inserted, removed, or
  125        *                 changed objects
  126        * @see TreePath
  127        */
  128       public TreeModelEvent(Object source, Object[] path, int[] childIndices,
  129                             Object[] children)
  130       {
  131           this(source, new TreePath(path), childIndices, children);
  132       }
  133   
  134       /**
  135        * Used to create an event when nodes have been changed, inserted, or
  136        * removed, identifying the path to the parent of the modified items as
  137        * a TreePath object. For more information on how to specify the indexes
  138        * and objects, see
  139        * <code>TreeModelEvent(Object,Object[],int[],Object[])</code>.
  140        *
  141        * @param source the Object responsible for generating the event (typically
  142        *               the creator of the event object passes <code>this</code>
  143        *               for its value)
  144        * @param path   a TreePath object that identifies the path to the
  145        *               parent of the modified item(s)
  146        * @param childIndices an array of <code>int</code> that specifies the
  147        *               index values of the modified items
  148        * @param children an array of Object containing the inserted, removed, or
  149        *                 changed objects
  150        *
  151        * @see #TreeModelEvent(Object,Object[],int[],Object[])
  152        */
  153       public TreeModelEvent(Object source, TreePath path, int[] childIndices,
  154                             Object[] children)
  155       {
  156           super(source);
  157           this.path = path;
  158           this.childIndices = childIndices;
  159           this.children = children;
  160       }
  161   
  162       /**
  163        * Used to create an event when the node structure has changed in some way,
  164        * identifying the path to the root of a modified subtree as an array of
  165        * Objects. A structure change event might involve nodes swapping position,
  166        * for example, or it might encapsulate multiple inserts and deletes in the
  167        * subtree stemming from the node, where the changes may have taken place at
  168        * different levels of the subtree.
  169        * <blockquote>
  170        *   <b>Note:</b><br>
  171        *   JTree collapses all nodes under the specified node, so that only its
  172        *   immediate children are visible.
  173        * </blockquote>
  174        *
  175        * @param source the Object responsible for generating the event (typically
  176        *               the creator of the event object passes <code>this</code>
  177        *               for its value)
  178        * @param path   an array of Object identifying the path to the root of the
  179        *               modified subtree, where the first element of the array is
  180        *               the object stored at the root node and the last element
  181        *               is the object stored at the changed node
  182        * @see TreePath
  183        */
  184       public TreeModelEvent(Object source, Object[] path)
  185       {
  186           this(source, new TreePath(path));
  187       }
  188   
  189       /**
  190        * Used to create an event when the node structure has changed in some way,
  191        * identifying the path to the root of the modified subtree as a TreePath
  192        * object. For more information on this event specification, see
  193        * <code>TreeModelEvent(Object,Object[])</code>.
  194        *
  195        * @param source the Object responsible for generating the event (typically
  196        *               the creator of the event object passes <code>this</code>
  197        *               for its value)
  198        * @param path   a TreePath object that identifies the path to the
  199        *               change. In the DefaultTreeModel,
  200        *               this object contains an array of user-data objects,
  201        *               but a subclass of TreePath could use some totally
  202        *               different mechanism -- for example, a node ID number
  203        *
  204        * @see #TreeModelEvent(Object,Object[])
  205        */
  206       public TreeModelEvent(Object source, TreePath path)
  207       {
  208           super(source);
  209           this.path = path;
  210           this.childIndices = new int[0];
  211       }
  212   
  213       /**
  214        * For all events, except treeStructureChanged,
  215        * returns the parent of the changed nodes.
  216        * For treeStructureChanged events, returns the ancestor of the
  217        * structure that has changed. This and
  218        * <code>getChildIndices</code> are used to get a list of the effected
  219        * nodes.
  220        * <p>
  221        * The one exception to this is a treeNodesChanged event that is to
  222        * identify the root, in which case this will return the root
  223        * and <code>getChildIndices</code> will return null.
  224        *
  225        * @return the TreePath used in identifying the changed nodes.
  226        * @see TreePath#getLastPathComponent
  227        */
  228       public TreePath getTreePath() { return path; }
  229   
  230       /**
  231        * Convenience method to get the array of objects from the TreePath
  232        * instance that this event wraps.
  233        *
  234        * @return an array of Objects, where the first Object is the one
  235        *         stored at the root and the last object is the one
  236        *         stored at the node identified by the path
  237        */
  238       public Object[] getPath() {
  239           if(path != null)
  240               return path.getPath();
  241           return null;
  242       }
  243   
  244       /**
  245        * Returns the objects that are children of the node identified by
  246        * <code>getPath</code> at the locations specified by
  247        * <code>getChildIndices</code>. If this is a removal event the
  248        * returned objects are no longer children of the parent node.
  249        *
  250        * @return an array of Object containing the children specified by
  251        *         the event
  252        * @see #getPath
  253        * @see #getChildIndices
  254        */
  255       public Object[] getChildren() {
  256           if(children != null) {
  257               int            cCount = children.length;
  258               Object[]       retChildren = new Object[cCount];
  259   
  260               System.arraycopy(children, 0, retChildren, 0, cCount);
  261               return retChildren;
  262           }
  263           return null;
  264       }
  265   
  266       /**
  267        * Returns the values of the child indexes. If this is a removal event
  268        * the indexes point to locations in the initial list where items
  269        * were removed. If it is an insert, the indices point to locations
  270        * in the final list where the items were added. For node changes,
  271        * the indices point to the locations of the modified nodes.
  272        *
  273        * @return an array of <code>int</code> containing index locations for
  274        *         the children specified by the event
  275        */
  276       public int[] getChildIndices() {
  277           if(childIndices != null) {
  278               int            cCount = childIndices.length;
  279               int[]          retArray = new int[cCount];
  280   
  281               System.arraycopy(childIndices, 0, retArray, 0, cCount);
  282               return retArray;
  283           }
  284           return null;
  285       }
  286   
  287       /**
  288        * Returns a string that displays and identifies this object's
  289        * properties.
  290        *
  291        * @return a String representation of this object
  292        */
  293       public String toString() {
  294           StringBuffer   retBuffer = new StringBuffer();
  295   
  296           retBuffer.append(getClass().getName() + " " +
  297                            Integer.toString(hashCode()));
  298           if(path != null)
  299               retBuffer.append(" path " + path);
  300           if(childIndices != null) {
  301               retBuffer.append(" indices [ ");
  302               for(int counter = 0; counter < childIndices.length; counter++)
  303                   retBuffer.append(Integer.toString(childIndices[counter])+ " ");
  304               retBuffer.append("]");
  305           }
  306           if(children != null) {
  307               retBuffer.append(" children [ ");
  308               for(int counter = 0; counter < children.length; counter++)
  309                   retBuffer.append(children[counter] + " ");
  310               retBuffer.append("]");
  311           }
  312           return retBuffer.toString();
  313       }
  314   }

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