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package javax.swing.tree;
import javax.swing.event.*;
The model used by JTree.
JTree and its related classes make extensive use of
TreePaths for identifying nodes in the TreeModel.
If a TreeModel returns the same object, as compared by
equals, at two different indices under the same parent
than the resulting TreePath objects will be considered equal
as well. Some implementations may assume that if two
TreePaths are equal, they identify the same node. If this
condition is not met, painting problems and other oddities may result.
In other words, if getChild for a given parent returns
the same Object (as determined by equals) problems may
result, and it is recommended you avoid doing this.
Similarly JTree and its related classes place
TreePaths in Maps. As such if
a node is requested twice, the return values must be equal
(using the equals method) and have the same
hashCode.
For further information on tree models,
including an example of a custom implementation,
see How to Use Trees
in The Java Tutorial.
Author: Rob Davis, Ray Ryan See Also: - TreePath
/**
* 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="https://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 null
only if the tree has no nodes.
Returns: the root of the tree
/**
* 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 parent at index index
in the parent's
child array. parent must be a node previously obtained
from this data source. This should not return null
if index
is a valid index for parent (that is index >= 0 &&
index < getChildCount(parent)).
Params: - parent – a node in the tree, obtained from this data source
Returns: the child of parent at index index
/**
* 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
* @return the child of <code>parent</code> at index <code>index</code>
*/
public Object getChild(Object parent, int index);
Returns the number of children of parent.
Returns 0 if the node
is a leaf or if it has no children. parent must be a node
previously obtained from this data source.
Params: - parent – a node in the tree, obtained from this data source
Returns: the number of children of the node parent
/**
* 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 true if node is a leaf.
It is possible for this method to return false
even if node 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.
Params: - node – a node in the tree, obtained from this data source
Returns: true if node is a leaf
/**
* 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 path to newValue.
If newValue signifies a truly new value
the model should post a treeNodesChanged event.
Params: - path – path to the node that the user has altered
- newValue – the new value from the TreeCellEditor
/**
* 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 parent
or child is null, returns -1.
If either parent or child don't
belong to this tree model, returns -1.
Params: - parent – a node in the tree, obtained from this data source
- child – the node we are interested in
Returns: the index of the child in the parent, or -1 if either
child or parent are null
or don't belong to this tree model
/**
* 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 TreeModelEvent
posted after the tree changes.
Params: - l – the listener to add
See Also:
/**
* 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
addTreeModelListener.
Params: - l – the listener to remove
See Also: - addTreeModelListener
/**
* Removes a listener previously added with
* <code>addTreeModelListener</code>.
*
* @see #addTreeModelListener
* @param l the listener to remove
*/
void removeTreeModelListener(TreeModelListener l);
}