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package javax.swing.event;

import java.util.EventObject;
import javax.swing.tree.TreePath;



Encapsulates information describing changes to a tree model, and
used to notify tree model listeners of the change.
For more information and examples see
How to Write a Tree Model Listener,
a section in The Java Tutorial.


Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans package. Please see XMLEncoder. 
Author:Rob Davis, Ray Ryan, Scott Violet
/**
 * Encapsulates information describing changes to a tree model, and
 * used to notify tree model listeners of the change.
 * For more information and examples see
 * <a
 href="http://java.sun.com/docs/books/tutorial/uiswing/events/treemodellistener.html">How to Write a Tree Model Listener</a>,
 * a section in <em>The Java Tutorial.</em>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans<sup><font size="-2">TM</font></sup>
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Rob Davis
 * @author Ray Ryan
 * @author Scott Violet
 */
public class TreeModelEvent extends EventObject {
    
Path to the parent of the nodes that have changed. 
/** Path to the parent of the nodes that have changed. */
    protected TreePath  path;
    
Indices identifying the position of where the children were. 
/** Indices identifying the position of where the children were. */
    protected int[]     childIndices;
    
Children that have been removed. 
/** Children that have been removed. */
    protected Object[]  children;

    
Used to create an event when nodes have been changed, inserted, or
removed, identifying the path to the parent of the modified items as
an array of Objects. All of the modified objects are siblings which are
direct descendents (not grandchildren) of the specified parent.
The positions at which the inserts, deletes, or changes occurred are
specified by an array of int. The indexes in that array
must be in order, from lowest to highest.


For changes, the indexes in the model correspond exactly to the indexes
of items currently displayed in the UI. As a result, it is not really
critical if the indexes are not in their exact order. But after multiple
inserts or deletes, the items currently in the UI no longer correspond
to the items in the model. It is therefore critical to specify the
indexes properly for inserts and deletes.


For inserts, the indexes represent the final state of the tree,
after the inserts have occurred. Since the indexes must be specified in
order, the most natural processing methodology is to do the inserts
starting at the lowest index and working towards the highest. Accumulate
a Vector of Integer objects that specify the
insert-locations as you go, then convert the Vector to an
array of int to create the event. When the postition-index
equals zero, the node is inserted at the beginning of the list. When the
position index equals the size of the list, the node is "inserted" at
(appended to) the end of the list.


For deletes, the indexes represent the initial state of the tree,
before the deletes have occurred. Since the indexes must be specified in
order, the most natural processing methodology is to use a delete-counter.
Start by initializing the counter to zero and start work through the
list from lowest to higest. Every time you do a delete, add the current
value of the delete-counter to the index-position where the delete occurred,
and append the result to a Vector of delete-locations, using
addElement(). Then increment the delete-counter. The index
positions stored in the Vector therefore reflect the effects of all previous
deletes, so they represent each object's position in the initial tree.
(You could also start at the highest index and working back towards the
lowest, accumulating a Vector of delete-locations as you go using the
insertElementAt(Integer, 0).) However you produce the Vector
of initial-positions, you then need to convert the Vector of Integer
objects to an array of int to create the event.


Notes:
    

  • Like the insertNodeInto method in the
   DefaultTreeModel class, insertElementAt
   appends to the Vector when the index matches the size
   of the vector. So you can use insertElementAt(Integer, 0)
   even when the vector is empty.

      To create a node changed event for the root node, specify the parent
    and the child indices as null.

    

Params:
  • source – the Object responsible for generating the event (typically
              the creator of the event object passes this
              for its value)
  • path –   an array of Object identifying the path to the
              parent of the modified item(s), where the first element
              of the array is the Object stored at the root node and
              the last element is the Object stored at the parent node
  • childIndices – an array of int that specifies the
              index values of the removed items. The indices must be
              in sorted order, from lowest to highest
  • children – an array of Object containing the inserted, removed, or
                changed objects
See Also:
/**
     * Used to create an event when nodes have been changed, inserted, or
     * removed, identifying the path to the parent of the modified items as
     * an array of Objects. All of the modified objects are siblings which are
     * direct descendents (not grandchildren) of the specified parent.
     * The positions at which the inserts, deletes, or changes occurred are
     * specified by an array of <code>int</code>. The indexes in that array
     * must be in order, from lowest to highest.
     * <p>
     * For changes, the indexes in the model correspond exactly to the indexes
     * of items currently displayed in the UI. As a result, it is not really
     * critical if the indexes are not in their exact order. But after multiple
     * inserts or deletes, the items currently in the UI no longer correspond
     * to the items in the model. It is therefore critical to specify the
     * indexes properly for inserts and deletes.
     * <p>
     * For inserts, the indexes represent the <i>final</i> state of the tree,
     * after the inserts have occurred. Since the indexes must be specified in
     * order, the most natural processing methodology is to do the inserts
     * starting at the lowest index and working towards the highest. Accumulate
     * a Vector of <code>Integer</code> objects that specify the
     * insert-locations as you go, then convert the Vector to an
     * array of <code>int</code> to create the event. When the postition-index
     * equals zero, the node is inserted at the beginning of the list. When the
     * position index equals the size of the list, the node is "inserted" at
     * (appended to) the end of the list.
     * <p>
     * For deletes, the indexes represent the <i>initial</i> state of the tree,
     * before the deletes have occurred. Since the indexes must be specified in
     * order, the most natural processing methodology is to use a delete-counter.
     * Start by initializing the counter to zero and start work through the
     * list from lowest to higest. Every time you do a delete, add the current
     * value of the delete-counter to the index-position where the delete occurred,
     * and append the result to a Vector of delete-locations, using
     * <code>addElement()</code>. Then increment the delete-counter. The index
     * positions stored in the Vector therefore reflect the effects of all previous
     * deletes, so they represent each object's position in the initial tree.
     * (You could also start at the highest index and working back towards the
     * lowest, accumulating a Vector of delete-locations as you go using the
     * <code>insertElementAt(Integer, 0)</code>.) However you produce the Vector
     * of initial-positions, you then need to convert the Vector of <code>Integer</code>
     * objects to an array of <code>int</code> to create the event.
     * <p>
     * <b>Notes:</b><ul>
     * <li>Like the <code>insertNodeInto</code> method in the
     *    <code>DefaultTreeModel</code> class, <code>insertElementAt</code>
     *    appends to the <code>Vector</code> when the index matches the size
     *    of the vector. So you can use <code>insertElementAt(Integer, 0)</code>
     *    even when the vector is empty.
     * <ul>To create a node changed event for the root node, specify the parent
     *     and the child indices as <code>null</code>.
     * </ul>
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this</code>
     *               for its value)
     * @param path   an array of Object identifying the path to the
     *               parent of the modified item(s), where the first element
     *               of the array is the Object stored at the root node and
     *               the last element is the Object stored at the parent node
     * @param childIndices an array of <code>int</code> that specifies the
     *               index values of the removed items. The indices must be
     *               in sorted order, from lowest to highest
     * @param children an array of Object containing the inserted, removed, or
     *                 changed objects
     * @see TreePath
     */
    public TreeModelEvent(Object source, Object[] path, int[] childIndices,
                          Object[] children)
    {
        this(source, new TreePath(path), childIndices, children);
    }

    
Used to create an event when nodes have been changed, inserted, or
removed, identifying the path to the parent of the modified items as
a TreePath object. For more information on how to specify the indexes
and objects, see
TreeModelEvent(Object,Object[],int[],Object[]).

Params:
  • source – the Object responsible for generating the event (typically
              the creator of the event object passes this
              for its value)
  • path –   a TreePath object that identifies the path to the
              parent of the modified item(s)
  • childIndices – an array of int that specifies the
              index values of the modified items
  • children – an array of Object containing the inserted, removed, or
                changed objects
See Also:
/**
     * Used to create an event when nodes have been changed, inserted, or
     * removed, identifying the path to the parent of the modified items as
     * a TreePath object. For more information on how to specify the indexes
     * and objects, see
     * <code>TreeModelEvent(Object,Object[],int[],Object[])</code>.
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this</code>
     *               for its value)
     * @param path   a TreePath object that identifies the path to the
     *               parent of the modified item(s)
     * @param childIndices an array of <code>int</code> that specifies the
     *               index values of the modified items
     * @param children an array of Object containing the inserted, removed, or
     *                 changed objects
     *
     * @see #TreeModelEvent(Object,Object[],int[],Object[])
     */
    public TreeModelEvent(Object source, TreePath path, int[] childIndices,
                          Object[] children)
    {
        super(source);
        this.path = path;
        this.childIndices = childIndices;
        this.children = children;
    }

    
Used to create an event when the node structure has changed in some way,
identifying the path to the root of a modified subtree as an array of
Objects. A structure change event might involve nodes swapping position,
for example, or it might encapsulate multiple inserts and deletes in the
subtree stemming from the node, where the changes may have taken place at
different levels of the subtree.


  Note:

  JTree collapses all nodes under the specified node, so that only its
  immediate children are visible.



Params:
  • source – the Object responsible for generating the event (typically
              the creator of the event object passes this
              for its value)
  • path –   an array of Object identifying the path to the root of the
              modified subtree, where the first element of the array is
              the object stored at the root node and the last element
              is the object stored at the changed node
See Also:
/**
     * Used to create an event when the node structure has changed in some way,
     * identifying the path to the root of a modified subtree as an array of
     * Objects. A structure change event might involve nodes swapping position,
     * for example, or it might encapsulate multiple inserts and deletes in the
     * subtree stemming from the node, where the changes may have taken place at
     * different levels of the subtree.
     * <blockquote>
     *   <b>Note:</b><br>
     *   JTree collapses all nodes under the specified node, so that only its
     *   immediate children are visible.
     * </blockquote>
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this</code>
     *               for its value)
     * @param path   an array of Object identifying the path to the root of the
     *               modified subtree, where the first element of the array is
     *               the object stored at the root node and the last element
     *               is the object stored at the changed node
     * @see TreePath
     */
    public TreeModelEvent(Object source, Object[] path)
    {
        this(source, new TreePath(path));
    }

    
Used to create an event when the node structure has changed in some way,
identifying the path to the root of the modified subtree as a TreePath
object. For more information on this event specification, see
TreeModelEvent(Object,Object[]).

Params:
  • source – the Object responsible for generating the event (typically
              the creator of the event object passes this
              for its value)
  • path –   a TreePath object that identifies the path to the
              change. In the DefaultTreeModel,
              this object contains an array of user-data objects,
              but a subclass of TreePath could use some totally
              different mechanism -- for example, a node ID number
See Also:
/**
     * Used to create an event when the node structure has changed in some way,
     * identifying the path to the root of the modified subtree as a TreePath
     * object. For more information on this event specification, see
     * <code>TreeModelEvent(Object,Object[])</code>.
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this</code>
     *               for its value)
     * @param path   a TreePath object that identifies the path to the
     *               change. In the DefaultTreeModel,
     *               this object contains an array of user-data objects,
     *               but a subclass of TreePath could use some totally
     *               different mechanism -- for example, a node ID number
     *
     * @see #TreeModelEvent(Object,Object[])
     */
    public TreeModelEvent(Object source, TreePath path)
    {
        super(source);
        this.path = path;
        this.childIndices = new int[0];
    }

    
For all events, except treeStructureChanged,
returns the parent of the changed nodes.
For treeStructureChanged events, returns the ancestor of the
structure that has changed. This and
getChildIndices are used to get a list of the effected
nodes.


The one exception to this is a treeNodesChanged event that is to
identify the root, in which case this will return the root
and getChildIndices will return null.

See Also:
Returns:the TreePath used in identifying the changed nodes.
/**
     * For all events, except treeStructureChanged,
     * returns the parent of the changed nodes.
     * For treeStructureChanged events, returns the ancestor of the
     * structure that has changed. This and
     * <code>getChildIndices</code> are used to get a list of the effected
     * nodes.
     * <p>
     * The one exception to this is a treeNodesChanged event that is to
     * identify the root, in which case this will return the root
     * and <code>getChildIndices</code> will return null.
     *
     * @return the TreePath used in identifying the changed nodes.
     * @see TreePath#getLastPathComponent
     */
    public TreePath getTreePath() { return path; }

    
Convenience method to get the array of objects from the TreePath
instance that this event wraps.

Returns:an array of Objects, where the first Object is the one
        stored at the root and the last object is the one
        stored at the node identified by the path
/**
     * Convenience method to get the array of objects from the TreePath
     * instance that this event wraps.
     *
     * @return an array of Objects, where the first Object is the one
     *         stored at the root and the last object is the one
     *         stored at the node identified by the path
     */
    public Object[] getPath() {
        if(path != null)
            return path.getPath();
        return null;
    }

    
Returns the objects that are children of the node identified by
getPath at the locations specified by
getChildIndices. If this is a removal event the
returned objects are no longer children of the parent node.

See Also:
Returns:an array of Object containing the children specified by
        the event
/**
     * Returns the objects that are children of the node identified by
     * <code>getPath</code> at the locations specified by
     * <code>getChildIndices</code>. If this is a removal event the
     * returned objects are no longer children of the parent node.
     *
     * @return an array of Object containing the children specified by
     *         the event
     * @see #getPath
     * @see #getChildIndices
     */
    public Object[] getChildren() {
        if(children != null) {
            int            cCount = children.length;
            Object[]       retChildren = new Object[cCount];

            System.arraycopy(children, 0, retChildren, 0, cCount);
            return retChildren;
        }
        return null;
    }

    
Returns the values of the child indexes. If this is a removal event
the indexes point to locations in the initial list where items
were removed. If it is an insert, the indices point to locations
in the final list where the items were added. For node changes,
the indices point to the locations of the modified nodes.

Returns:an array of int containing index locations for
        the children specified by the event
/**
     * Returns the values of the child indexes. If this is a removal event
     * the indexes point to locations in the initial list where items
     * were removed. If it is an insert, the indices point to locations
     * in the final list where the items were added. For node changes,
     * the indices point to the locations of the modified nodes.
     *
     * @return an array of <code>int</code> containing index locations for
     *         the children specified by the event
     */
    public int[] getChildIndices() {
        if(childIndices != null) {
            int            cCount = childIndices.length;
            int[]          retArray = new int[cCount];

            System.arraycopy(childIndices, 0, retArray, 0, cCount);
            return retArray;
        }
        return null;
    }

    
Returns a string that displays and identifies this object's
properties.

Returns:a String representation of this object
/**
     * Returns a string that displays and identifies this object's
     * properties.
     *
     * @return a String representation of this object
     */
    public String toString() {
        StringBuffer   retBuffer = new StringBuffer();

        retBuffer.append(getClass().getName() + " " +
                         Integer.toString(hashCode()));
        if(path != null)
            retBuffer.append(" path " + path);
        if(childIndices != null) {
            retBuffer.append(" indices [ ");
            for(int counter = 0; counter < childIndices.length; counter++)
                retBuffer.append(Integer.toString(childIndices[counter])+ " ");
            retBuffer.append("]");
        }
        if(children != null) {
            retBuffer.append(" children [ ");
            for(int counter = 0; counter < children.length; counter++)
                retBuffer.append(children[counter] + " ");
            retBuffer.append("]");
        }
        return retBuffer.toString();
    }
}