How to Write a Tree Model Listener - Java Tutorial 5.0 英文版

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Trail: Creating a GUI with JFC/Swing
Lesson: Writing Event Listeners

How to Write a Tree Model Listener

By implementing a tree model listener, you can detect when the data displayed by a tree changes. You might use a tree model listener to detect when the user edits tree nodes. To see an example and discussion of doing so, read Dynamically Changing a Tree .

The Tree Model Listener API

The TreeModelListener Interface
TreeModelListener has no adapter class.

Method Purpose

treeNodesChanged(TreeModelEvent) Called when one or more sibling nodes have changed in some way.

treeNodesInserted(TreeModelEvent) Called after nodes have been inserted into the tree.

treeNodesRemoved(TreeModelEvent) Called after nodes have been removed from the tree.

treeStructureChanged(TreeModelEvent) Called after the tree's structure has drastically changed.

The TreeModelEvent API

Method Purpose

Object getSource()
(in java.util.EventObject) Return the object that fired the event.

int[] getChildIndices() For treeNodesChanged, treeNodesInserted, and treeNodesRemoved, returns the indices of the changed, inserted, or deleted nodes, respectively. Returns nothing useful for treeStructureChanged.

Object[] getChildren() Returns the objects corresponding to the child indices.

Object[] getPath() Returns the path to the parent of the changed, inserted, or deleted nodes. For treeStructureChanged, returns the path to the node beneath which the structure has changed.

TreePath getTreePath() Returns the same thing as getPath, but as a TreePath object.

Method	Purpose
`treeNodesChanged(TreeModelEvent)`	Called when one or more sibling nodes have changed in some way.
`treeNodesInserted(TreeModelEvent)`	Called after nodes have been inserted into the tree.
`treeNodesRemoved(TreeModelEvent)`	Called after nodes have been removed from the tree.
`treeStructureChanged(TreeModelEvent)`	Called after the tree's structure has drastically changed.

Method	Purpose
`Object getSource()` (in `java.util.EventObject`)	Return the object that fired the event.
`int[] getChildIndices()`	For `treeNodesChanged`, `treeNodesInserted`, and `treeNodesRemoved`, returns the indices of the changed, inserted, or deleted nodes, respectively. Returns nothing useful for `treeStructureChanged`.
`Object[] getChildren()`	Returns the objects corresponding to the child indices.
`Object[] getPath()`	Returns the path to the parent of the changed, inserted, or deleted nodes. For `treeStructureChanged`, returns the path to the node beneath which the structure has changed.
`TreePath getTreePath()`	Returns the same thing as `getPath`, but as a `TreePath` object.

Examples that Use Tree Model Listeners

The following table lists the examples that use tree expansion listeners.

Example Where Described Notes

DynamicTreeDemo How to Use Trees The DynamicTree class implements a tree model listener to detect when the user has edited a node's data.

Example	Where Described	Notes
`DynamicTreeDemo`	How to Use Trees	The `DynamicTree` class implements a tree model listener to detect when the user has edited a node's data.

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