TreeModel (Java SE 19 & JDK 19) (original) (raw)

All Known Implementing Classes:

[DefaultTreeModel](DefaultTreeModel.html "class in javax.swing.tree")

public interface TreeModel

The model used by JTree.

JTree and its related classes make extensive use ofTreePaths for identifying nodes in the TreeModel. If a TreeModel returns the same object, as compared byequals, 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 twoTreePaths 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 placeTreePaths in Maps. As such if a node is requested twice, the return values must be equal (using the equals method) and have the samehashCode.

For further information on tree models, including an example of a custom implementation, see How to Use Trees in The Java Tutorial.

See Also:

• TreePath

• Method Summary

void
Adds a listener for the TreeModelEvent posted after the tree changes.
[getChild](#getChild%28java.lang.Object,int%29)([Object](../../../../java.base/java/lang/Object.html "class in java.lang") parent, int index)
Returns the child of parent at index index in the parent's child array.
int
Returns the number of children of parent.
int
Returns the index of child in parent.
[getRoot](#getRoot%28%29)()
Returns the root of the tree.
boolean
Returns true if node is a leaf.
void
Removes a listener previously added withaddTreeModelListener.
void
Messaged when the user has altered the value for the item identified by path to newValue.

• Method Details

  • getRoot

  Returns the root of the tree. Returns null only if the tree has no nodes.
  Returns:
  the root of the tree

  • getChild

  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)).
  Parameters:
  parent - a node in the tree, obtained from this data source
  index - index of child to be returned
  Returns:
  the child of parent at index index

  • getChildCount

  int getChildCount(Object parent)
  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.
  Parameters:
  parent - a node in the tree, obtained from this data source
  Returns:
  the number of children of the node parent

  • isLeaf

  boolean isLeaf(Object node)
  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.
  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 by path to newValue. If newValue signifies a truly new value the model should post a treeNodesChanged event.
  Parameters:
  path - path to the node that the user has altered
  newValue - the new value from the TreeCellEditor

  • getIndexOfChild

  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.
  Parameters:
  parent - a node in the tree, obtained from this data source
  child - the node we are interested in
  Returns:
  the index of the child in the parent, or -1 if eitherchild or parent are null or don't belong to this tree model

  • addTreeModelListener

  Adds a listener for the TreeModelEvent posted after the tree changes.
  Parameters:
  l - the listener to add
  See Also:
  * removeTreeModelListener(javax.swing.event.TreeModelListener)

  • removeTreeModelListener

  Removes a listener previously added withaddTreeModelListener.
  Parameters:
  l - the listener to remove
  See Also:
  * addTreeModelListener(javax.swing.event.TreeModelListener)