Java tutorial
/* * 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.tree; import javax.swing.event.*; /** * The model used by <code>JTree</code>. * <p> * <code>JTree</code> and its related classes make extensive use of * <code>TreePath</code>s for identifying nodes in the <code>TreeModel</code>. * If a <code>TreeModel</code> returns the same object, as compared by * <code>equals</code>, at two different indices under the same parent * than the resulting <code>TreePath</code> objects will be considered equal * as well. Some implementations may assume that if two * <code>TreePath</code>s are equal, they identify the same node. If this * condition is not met, painting problems and other oddities may result. * In other words, if <code>getChild</code> for a given parent returns * the same Object (as determined by <code>equals</code>) problems may * result, and it is recommended you avoid doing this. * <p> * Similarly <code>JTree</code> and its related classes place * <code>TreePath</code>s in <code>Map</code>s. As such if * a node is requested twice, the return values must be equal * (using the <code>equals</code> method) and have the same * <code>hashCode</code>. * <p> * For further information on tree models, * including an example of a custom implementation, * see <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/tree.html">How to Use Trees</a> * in <em>The Java Tutorial.</em> * * @see TreePath * * @author Rob Davis * @author Ray Ryan */ public interface TreeModel { /** * Returns the root of the tree. Returns <code>null</code> * only if the tree has no nodes. * * @return the root of the tree */ public Object getRoot(); /** * Returns the child of <code>parent</code> at index <code>index</code> * in the parent's * child array. <code>parent</code> must be a node previously obtained * from this data source. This should not return <code>null</code> * if <code>index</code> * is a valid index for <code>parent</code> (that is <code>index >= 0 && * index < getChildCount(parent</code>)). * * @param parent a node in the tree, obtained from this data source * @param index index of child to be returned * @return the child of {@code parent} at index {@code index} */ public Object getChild(Object parent, int index); /** * Returns the number of children of <code>parent</code>. * Returns 0 if the node * is a leaf or if it has no children. <code>parent</code> must be a node * previously obtained from this data source. * * @param parent a node in the tree, obtained from this data source * @return the number of children of the node <code>parent</code> */ public int getChildCount(Object parent); /** * Returns <code>true</code> if <code>node</code> is a leaf. * It is possible for this method to return <code>false</code> * even if <code>node</code> has no children. * A directory in a filesystem, for example, * may contain no files; the node representing * the directory is not a leaf, but it also has no children. * * @param node a node in the tree, obtained from this data source * @return true if <code>node</code> is a leaf */ public boolean isLeaf(Object node); /** * Messaged when the user has altered the value for the item identified * by <code>path</code> to <code>newValue</code>. * If <code>newValue</code> signifies a truly new value * the model should post a <code>treeNodesChanged</code> event. * * @param path path to the node that the user has altered * @param newValue the new value from the TreeCellEditor */ public void valueForPathChanged(TreePath path, Object newValue); /** * Returns the index of child in parent. If either <code>parent</code> * or <code>child</code> is <code>null</code>, returns -1. * If either <code>parent</code> or <code>child</code> don't * belong to this tree model, returns -1. * * @param parent a node in the tree, obtained from this data source * @param child the node we are interested in * @return the index of the child in the parent, or -1 if either * <code>child</code> or <code>parent</code> are <code>null</code> * or don't belong to this tree model */ public int getIndexOfChild(Object parent, Object child); // // Change Events // /** * Adds a listener for the <code>TreeModelEvent</code> * posted after the tree changes. * * @param l the listener to add * @see #removeTreeModelListener */ void addTreeModelListener(TreeModelListener l); /** * Removes a listener previously added with * <code>addTreeModelListener</code>. * * @see #addTreeModelListener * @param l the listener to remove */ void removeTreeModelListener(TreeModelListener l); }