# Interface TreeModelListener

All Superinterfaces:
  `EventListener`

All Known Implementing Classes:
  `BasicTreeUI.TreeModelHandler`, `JTree.AccessibleJTree`, `JTree.TreeModelHandler`

public interface TreeModelListener extends EventListener
Defines the interface for an object that listens to changes in a TreeModel. For further information and examples see How to Write a Tree Model Listener, a section in The Java Tutorial.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `treeNodesChanged(TreeModelEvent e)`
  Invoked after a node (or a set of siblings) has changed in some way.
  `void`
  `treeNodesInserted(TreeModelEvent e)`
  Invoked after nodes have been inserted into the tree.
  `void`
  `treeNodesRemoved(TreeModelEvent e)`
  Invoked after nodes have been removed from the tree.
  `void`
  `treeStructureChanged(TreeModelEvent e)`
  Invoked after the tree has drastically changed structure from a given node down.

- ## Method Details

  - ### treeNodesChanged

    void treeNodesChanged(TreeModelEvent e)

    Invoked after a node (or a set of siblings) has changed in some way. The node(s) have not changed locations in the tree or altered their children arrays, but other attributes have changed and may affect presentation. Example: the name of a file has changed, but it is in the same location in the file system.

    To indicate the root has changed, childIndices and children will be null.

    Use `e.getPath()` to get the parent of the changed node(s). `e.getChildIndices()` returns the index(es) of the changed node(s).

    Parameters:
      `e` - a `TreeModelEvent` describing changes to a tree model

  - ### treeNodesInserted

    void treeNodesInserted(TreeModelEvent e)

    Invoked after nodes have been inserted into the tree.

    Use `e.getPath()` to get the parent of the new node(s). `e.getChildIndices()` returns the index(es) of the new node(s) in ascending order.

    Parameters:
      `e` - a `TreeModelEvent` describing changes to a tree model

  - ### treeNodesRemoved

    void treeNodesRemoved(TreeModelEvent e)

    Invoked after nodes have been removed from the tree. Note that if a subtree is removed from the tree, this method may only be invoked once for the root of the removed subtree, not once for each individual set of siblings removed.

    Use `e.getPath()` to get the former parent of the deleted node(s). `e.getChildIndices()` returns, in ascending order, the index(es) the node(s) had before being deleted.

    Parameters:
      `e` - a `TreeModelEvent` describing changes to a tree model

  - ### treeStructureChanged

    void treeStructureChanged(TreeModelEvent e)

    Invoked after the tree has drastically changed structure from a given node down. If the path returned by e.getPath() is of length one and the first element does not identify the current root node the first element should become the new root of the tree.

    Use `e.getPath()` to get the path to the node. `e.getChildIndices()` returns null.

    Parameters:
      `e` - a `TreeModelEvent` describing changes to a tree model