TreeModel


1   /*
2    * @(#)TreeModel.java   1.23 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package javax.swing.tree;
8   
9   import javax.swing.event.*;
10  
11  /**
12   * The interface that defines a suitable data model for a <code>JTree</code>. 
13   * For further information on tree models,
14   * including an example of a custom implementation,
15   * see <a
16   href="http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html">How to Use Trees</a>
17   * in <em>The Java Tutorial.</em>
18   * <p>
19   * <code>JTree</code> and its related classes make extensive use of
20   * <code>TreePath</code>s for indentifying nodes in the <code>TreeModel</code>.
21   * If a <code>TreeModel</code> returns the same object, as compared by
22   * <code>equals</code>, at two different indices under the same parent
23   * than the resulting <code>TreePath</code> objects will be considered equal
24   * as well. Some implementations may assume that if two
25   * <code>TreePath</code>s are equal, they identify the same node. If this
26   * condition is not met, painting problems and other oddities may result.
27   * In other words, if <code>getChild</code> for a given parent returns
28   * the same Object (as determined by <code>equals</code>) problems may
29   * result, and it is recommended you avoid doing this.
30   * 
31   * @see TreePath
32   * 
33   * @version 1.23 12/19/03
34   * @author Rob Davis
35   * @author Ray Ryan
36   */
37  public interface TreeModel
38  {
39  
40      /**
41       * Returns the root of the tree.  Returns <code>null</code>
42       * only if the tree has no nodes.
43       *
44       * @return  the root of the tree
45       */
46      public Object   getRoot();
47  
48  
49      /**
50       * Returns the child of <code>parent</code> at index <code>index</code>
51       * in the parent's
52       * child array.  <code>parent</code> must be a node previously obtained
53       * from this data source. This should not return <code>null</code>
54       * if <code>index</code>
55       * is a valid index for <code>parent</code> (that is <code>index >= 0 &&
56       * index < getChildCount(parent</code>)).
57       *
58       * @param   parent  a node in the tree, obtained from this data source
59       * @return  the child of <code>parent</code> at index <code>index</code>
60       */
61      public Object   getChild(Object   parent, int index);
62  
63  
64      /**
65       * Returns the number of children of <code>parent</code>.
66       * Returns 0 if the node
67       * is a leaf or if it has no children.  <code>parent</code> must be a node
68       * previously obtained from this data source.
69       *
70       * @param   parent  a node in the tree, obtained from this data source
71       * @return  the number of children of the node <code>parent</code>
72       */
73      public int getChildCount(Object   parent);
74  
75  
76      /**
77       * Returns <code>true</code> if <code>node</code> is a leaf.
78       * It is possible for this method to return <code>false</code>
79       * even if <code>node</code> has no children.
80       * A directory in a filesystem, for example,
81       * may contain no files; the node representing
82       * the directory is not a leaf, but it also has no children.
83       *
84       * @param   node  a node in the tree, obtained from this data source
85       * @return  true if <code>node</code> is a leaf
86       */
87      public boolean isLeaf(Object   node);
88  
89      /**
90        * Messaged when the user has altered the value for the item identified
91        * by <code>path</code> to <code>newValue</code>. 
92        * If <code>newValue</code> signifies a truly new value
93        * the model should post a <code>treeNodesChanged</code> event.
94        *
95        * @param path path to the node that the user has altered
96        * @param newValue the new value from the TreeCellEditor
97        */
98      public void valueForPathChanged(TreePath   path, Object   newValue);
99  
100     /**
101      * Returns the index of child in parent.  If either <code>parent</code>
102      * or <code>child</code> is <code>null</code>, returns -1.
103      * If either <code>parent</code> or <code>child</code> don't
104      * belong to this tree model, returns -1.
105      *
106      * @param parent a note in the tree, obtained from this data source
107      * @param child the node we are interested in
108      * @return the index of the child in the parent, or -1 if either
109      *    <code>child</code> or <code>parent</code> are <code>null</code>
110      *    or don't belong to this tree model
111      */
112     public int getIndexOfChild(Object   parent, Object   child);
113 
114 //
115 //  Change Events
116 //
117 
118     /**
119      * Adds a listener for the <code>TreeModelEvent</code>
120      * posted after the tree changes.
121      *
122      * @param   l       the listener to add
123      * @see     #removeTreeModelListener
124      */
125     void addTreeModelListener(TreeModelListener l);
126 
127     /**
128      * Removes a listener previously added with
129      * <code>addTreeModelListener</code>.
130      *
131      * @see     #addTreeModelListener
132      * @param   l       the listener to remove
133      */  
134     void removeTreeModelListener(TreeModelListener l);
135 
136 }
137
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