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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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

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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="http://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 &gt;= 0 &amp;&amp;

     * index &lt; 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);

}