Java example source code file (TreeModelEvent.java)

This example Java source code file (TreeModelEvent.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

eventobject, jtree, object, stringbuffer, tree, treemodelevent, treepath, util

The TreeModelEvent.java Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

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
 * <a
 href="http://docs.oracle.com/javase/tutorial/uiswing/events/treemodellistener.html">How to Write a Tree Model Listener</a>,
 * a section in <em>The Java Tutorial.
 * <p>
 * <strong>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 JavaBeans™
 * has been added to the <code>java.beans 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. */
    protected TreePath  path;
    /** Indices identifying the position of where the children were. */
    protected int[]     childIndices;
    /** 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 <code>int. 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 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 objects that specify the
     * insert-locations as you go, then convert the Vector to an
     * array of <code>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.
     * <p>
     * For deletes, the indexes represent the <i>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 highest. 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(). 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).) However you produce the Vector
     * of initial-positions, you then need to convert the Vector of <code>Integer
     * objects to an array of <code>int to create the event.
     * <p>
     * <b>Notes:

     * <li>Like the insertNodeInto method in the
     *    <code>DefaultTreeModel class, insertElementAt
     *    appends to the <code>Vector when the index matches the size
     *    of the vector. So you can use <code>insertElementAt(Integer, 0)
     *    even when the vector is empty.</li>
     * <li>To create a node changed event for the root node, specify the parent
     *     and the child indices as <code>null.
     * </ul>
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this
     *               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 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, (path == null) ? null : 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
     * <code>TreeModelEvent(Object,Object[],int[],Object[]).
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this
     *               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 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.
     * <blockquote>
     *   <b>Note:

     *   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
     *               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, (path == null) ? null : 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
     * <code>TreeModelEvent(Object,Object[]).
     *
     * @param source the Object responsible for generating the event (typically
     *               the creator of the event object passes <code>this
     *               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
     * <code>getChildIndices 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 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.
     *
     * @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
     * <code>getPath at the locations specified by
     * <code>getChildIndices. 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.
     *
     * @return an array of <code>int 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.
     *
     * @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();
    }
}