1 /* 2 * Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package javax.swing.tree; 26 27 import javax.swing.event.*; 28 29 /** 30 * The model used by <code>JTree</code>. 31 * <p> 32 * <code>JTree</code> and its related classes make extensive use of 33 * <code>TreePath</code>s for indentifying nodes in the <code>TreeModel</code>. 34 * If a <code>TreeModel</code> returns the same object, as compared by 35 * <code>equals</code>, at two different indices under the same parent 36 * than the resulting <code>TreePath</code> objects will be considered equal 37 * as well. Some implementations may assume that if two 38 * <code>TreePath</code>s are equal, they identify the same node. If this 39 * condition is not met, painting problems and other oddities may result. 40 * In other words, if <code>getChild</code> for a given parent returns 41 * the same Object (as determined by <code>equals</code>) problems may 42 * result, and it is recommended you avoid doing this. 43 * <p> 44 * Similarly <code>JTree</code> and its related classes place 45 * <code>TreePath</code>s in <code>Map</code>s. As such if 46 * a node is requested twice, the return values must be equal 47 * (using the <code>equals</code> method) and have the same 48 * <code>hashCode</code>. 49 * <p> 50 * For further information on tree models, 51 * including an example of a custom implementation, 52 * see <a 53 href="http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html">How to Use Trees</a> 54 * in <em>The Java Tutorial.</em> 55 * 56 * @see TreePath 57 * 58 * @author Rob Davis 59 * @author Ray Ryan 60 */ 61 public interface TreeModel 62 { 63 64 /** 65 * Returns the root of the tree. Returns <code>null</code> 66 * only if the tree has no nodes. 67 * 68 * @return the root of the tree 69 */ 70 public Object getRoot(); 71 72 73 /** 74 * Returns the child of <code>parent</code> at index <code>index</code> 75 * in the parent's 76 * child array. <code>parent</code> must be a node previously obtained 77 * from this data source. This should not return <code>null</code> 78 * if <code>index</code> 79 * is a valid index for <code>parent</code> (that is <code>index >= 0 && 80 * index < getChildCount(parent</code>)). 81 * 82 * @param parent a node in the tree, obtained from this data source 83 * @return the child of <code>parent</code> at index <code>index</code> 84 */ 85 public Object getChild(Object parent, int index); 86 87 88 /** 89 * Returns the number of children of <code>parent</code>. 90 * Returns 0 if the node 91 * is a leaf or if it has no children. <code>parent</code> must be a node 92 * previously obtained from this data source. 93 * 94 * @param parent a node in the tree, obtained from this data source 95 * @return the number of children of the node <code>parent</code> 96 */ 97 public int getChildCount(Object parent); 98 99 100 /** 101 * Returns <code>true</code> if <code>node</code> is a leaf. 102 * It is possible for this method to return <code>false</code> 103 * even if <code>node</code> has no children. 104 * A directory in a filesystem, for example, 105 * may contain no files; the node representing 106 * the directory is not a leaf, but it also has no children. 107 * 108 * @param node a node in the tree, obtained from this data source 109 * @return true if <code>node</code> is a leaf 110 */ 111 public boolean isLeaf(Object node); 112 113 /** 114 * Messaged when the user has altered the value for the item identified 115 * by <code>path</code> to <code>newValue</code>. 116 * If <code>newValue</code> signifies a truly new value 117 * the model should post a <code>treeNodesChanged</code> event. 118 * 119 * @param path path to the node that the user has altered 120 * @param newValue the new value from the TreeCellEditor 121 */ 122 public void valueForPathChanged(TreePath path, Object newValue); 123 124 /** 125 * Returns the index of child in parent. If either <code>parent</code> 126 * or <code>child</code> is <code>null</code>, returns -1. 127 * If either <code>parent</code> or <code>child</code> don't 128 * belong to this tree model, returns -1. 129 * 130 * @param parent a node in the tree, obtained from this data source 131 * @param child the node we are interested in 132 * @return the index of the child in the parent, or -1 if either 133 * <code>child</code> or <code>parent</code> are <code>null</code> 134 * or don't belong to this tree model 135 */ 136 public int getIndexOfChild(Object parent, Object child); 137 138 // 139 // Change Events 140 // 141 142 /** 143 * Adds a listener for the <code>TreeModelEvent</code> 144 * posted after the tree changes. 145 * 146 * @param l the listener to add 147 * @see #removeTreeModelListener 148 */ 149 void addTreeModelListener(TreeModelListener l); 150 151 /** 152 * Removes a listener previously added with 153 * <code>addTreeModelListener</code>. 154 * 155 * @see #addTreeModelListener 156 * @param l the listener to remove 157 */ 158 void removeTreeModelListener(TreeModelListener l); 159 160 }