Java tutorial
/* * Copyright (c) 1997, 2014, 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="https://docs.oracle.com/javase/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™ * 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 */ @SuppressWarnings("serial") // Same-version serialization only 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</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 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()</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 style="list-style-type:none"> * <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.</li> * <li>To create a node changed event for the root node, specify the parent * and the child indices as <code>null</code>.</li> * </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, (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[])</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. * <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, (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[])</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 * <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. * * @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</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. * * @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. * * @return a String representation of this object */ public String toString() { StringBuilder sb = new StringBuilder(); sb.append(getClass().getName() + " " + Integer.toString(hashCode())); if (path != null) sb.append(" path " + path); if (childIndices != null) { sb.append(" indices [ "); for (int counter = 0; counter < childIndices.length; counter++) sb.append(Integer.toString(childIndices[counter]) + " "); sb.append("]"); } if (children != null) { sb.append(" children [ "); for (int counter = 0; counter < children.length; counter++) sb.append(children[counter] + " "); sb.append("]"); } return sb.toString(); } }