Tree Nodes and Paths
You probably noticed that the DefaultTreeModel class depends on TreeNode and TreePath objects. In a tree, a TreeNode represents an individual piece of
data stored at a particular point in a tree, and a path represents a
collection of these pieces that are directly related to each other (in
an ancestor/descendant relationship). Let’s look at the classes that
make up the typical nodes and paths.
The TreeNode Interface
A TreeNode is the
basic unit of a tree. This interface defines the minimum properties
and access routines a typical tree model expects to see in its
nodes.
Properties
The TreeNode interface
contains the properties listed in Table 17-6. The TreeNode properties are straightforward
and deal with the structure of the node. The parent property holds a valid value for every node in a
tree, except the root. The childAt property lets you access a
particular child in the tree. The childCount property contains the number of
children associated with this node, if it allows children.
If the node does not allow children, it is probably a
leaf, but it is also possible to have a mutable tree node that has
no children, or does not allow children, and yet is not a leaf. (An
empty directory with no write permissions would be an example of
such a node.)
Table 17-6. TreeNode properties
Property | Data type | get | is | set | Default value |
|---|---|---|---|---|---|
allowsChildren | boolean | · | |||
childAti | TreeNode | · | |||
childCount | int | · | |||
leaf | boolean | · | |||
parent | TreeNode | · | |||
iindexed |
Notice that the children are not properties ...
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