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.
*
* @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.
*
* @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)).
*
* @param parent a node in the tree, obtained from this data source
* @return the child of parent at index index
*/
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.
*
* @param parent a node in the tree, obtained from this data source
* @return the number of children of the node parent
*/
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.
*
* @param node a node in the tree, obtained from this data source
* @return true if node 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.
*
* @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.
*
* @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
* child or parent are null
* 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.
*
* @param l the listener to add
* @see #removeTreeModelListener
*/
void addTreeModelListener(TreeModelListener l);
/**
* Removes a listener previously added with
* addTreeModelListener.
*
* @see #addTreeModelListener
* @param l the listener to remove
*/
void removeTreeModelListener(TreeModelListener l);
}