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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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 >= 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);
}