- All Known Implementing Classes:
DefaultTreeModel
JTree
.
JTree
and its related classes make extensive use of
TreePath
s 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
then the resulting TreePath
objects will be considered equal
as well. Some implementations may assume that if two
TreePath
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 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
TreePath
s in Map
s. 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 Also:
-
Method Summary
Modifier and TypeMethodDescriptionvoid
Adds a listener for theTreeModelEvent
posted after the tree changes.Returns the child ofparent
at indexindex
in the parent's child array.int
getChildCount
(Object parent) Returns the number of children ofparent
.int
getIndexOfChild
(Object parent, Object child) Returns the index of child in parent.getRoot()
Returns the root of the tree.boolean
Returnstrue
ifnode
is a leaf.void
Removes a listener previously added withaddTreeModelListener
.void
valueForPathChanged
(TreePath path, Object newValue) Messaged when the user has altered the value for the item identified bypath
tonewValue
.
-
Method Details
-
getRoot
Object getRoot()Returns the root of the tree. Returnsnull
only if the tree has no nodes.- Returns:
- the root of the tree
-
getChild
Returns the child ofparent
at indexindex
in the parent's child array.parent
must be a node previously obtained from this data source. This should not returnnull
ifindex
is a valid index forparent
(that isindex >= 0 && index < getChildCount(parent
)).- Parameters:
parent
- a node in the tree, obtained from this data sourceindex
- index of child to be returned- Returns:
- the child of
parent
at indexindex
-
getChildCount
Returns the number of children ofparent
. 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.- Parameters:
parent
- a node in the tree, obtained from this data source- Returns:
- the number of children of the node
parent
-
isLeaf
Returnstrue
ifnode
is a leaf. It is possible for this method to returnfalse
even ifnode
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.- Parameters:
node
- a node in the tree, obtained from this data source- Returns:
- true if
node
is a leaf
-
valueForPathChanged
Messaged when the user has altered the value for the item identified bypath
tonewValue
. IfnewValue
signifies a truly new value the model should post atreeNodesChanged
event.- Parameters:
path
- path to the node that the user has alterednewValue
- the new value from the TreeCellEditor
-
getIndexOfChild
Returns the index of child in parent. If eitherparent
orchild
isnull
, returns -1. If eitherparent
orchild
don't belong to this tree model, returns -1.- Parameters:
parent
- a node in the tree, obtained from this data sourcechild
- the node we are interested in- Returns:
- the index of the child in the parent, or -1 if either
child
orparent
arenull
or don't belong to this tree model
-
addTreeModelListener
Adds a listener for theTreeModelEvent
posted after the tree changes.- Parameters:
l
- the listener to add- See Also:
-
removeTreeModelListener
Removes a listener previously added withaddTreeModelListener
.- Parameters:
l
- the listener to remove- See Also:
-