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     /**

  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://docs.oracle.com/javase/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     /**