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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class TreeModelEvent - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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javax.swing.event
Class TreeModelEvent

java.lang.Object
  |
  +--java.util.EventObject
        |
        +--javax.swing.event.TreeModelEvent
public class TreeModelEvent
extends EventObject

Encapsulates information describing changes to a tree model, and used to notify tree model listeners of the change.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. A future release of Swing will provide support for long term persistence.

See Also:
Serialized Form

Field Summary
protected  int[] childIndices
          Indices identifying the position of where the children were.
protected  Object[] children
          Children that have been removed.
protected  TreePath path
          Path to the parent of the nodes that have changed.
 
Fields inherited from class java.util.EventObject
source
 
Constructor Summary
TreeModelEvent(Object source, Object[] path)
          Used to create an event when the node structure has changed in some way, identifying the path to the root of a modified subtree as an array of Objects.
TreeModelEvent(Object source, Object[] path, int[] childIndices, Object[] children)
          Used to create an event when nodes have been changed, inserted, or removed, identifying the path to the parent of the modified items as an array of Objects.
TreeModelEvent(Object source, TreePath path)
          Used to create an event when the node structure has changed in some way, identifying the path to the root of the modified subtree as a TreePath object.
TreeModelEvent(Object source, TreePath path, int[] childIndices, Object[] children)
          Used to create an event when nodes have been changed, inserted, or removed, identifying the path to the parent of the modified items as a TreePath object.
 
Method Summary
 int[] getChildIndices()
          Returns the values of the child indexes.
 Object[] getChildren()
          Returns the objects that are children of the node identified by getPath at the locations specified by getChildIndices.
 Object[] getPath()
          Convenience method to get the array of objects from the TreePath instance that this event wraps.
 TreePath getTreePath()
          Returns the TreePath object identifying the changed node.
 String toString()
          Returns a string that displays and identifies this object's properties.
 
Methods inherited from class java.util.EventObject
getSource
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

path

protected TreePath path
Path to the parent of the nodes that have changed.

childIndices

protected int[] childIndices
Indices identifying the position of where the children were.

children

protected Object[] children
Children that have been removed.
Constructor Detail

TreeModelEvent

public TreeModelEvent(Object source,
                      Object[] path,
                      int[] childIndices,
                      Object[] children)
Used to create an event when nodes have been changed, inserted, or removed, identifying the path to the parent of the modified items as an array of Objects. All of the modified objects are siblings which are direct descendents (not grandchildren) of the specified parent. The positions at which the inserts, deletes, or changes occured are specified by an array of int. The indexes in that array must be in order, from lowest to highest.

For changes, the indexes in the model correspond exactly to the indexes of items currently displayed in the UI. As a result, it is not really critical if the indexes are not in their exact order. But after multiple inserts or deletes, the items currently in the UI no longer correspond to the items in the model. It is therefore critical to specify the indexes properly for inserts and deletes.

For inserts, the indexes represent the final state of the tree, after the inserts have occurred. Since the indexes must be specified in order, the most natural processing methodology is to do the inserts starting at the lowest index and working towards the highest. Accumulate a Vector of Integer objects that specify the insert-locations as you go, then convert the Vector to an array of int to create the event. When the postition-index equals zero, the node is inserted at the beginning of the list. When the position index equals the size of the list, the node is "inserted" at (appended to) the end of the list.

For deletes, the indexes represent the initial state of the tree, before the deletes have occurred. Since the indexes must be specified in order, the most natural processing methodology is to use a delete-counter. Start by initializing the counter to zero and start work through the list from lowest to higest. Every time you do a delete, add the current value of the delete-counter to the index-position where the delete occurred, and append the result to a Vector of delete-locations, using addElement(). Then increment the delete-counter. The index positions stored in the Vector therefore reflect the effects of all previous deletes, so they represent each object's position in the initial tree. (You could also start at the highest index and working back towards the lowest, accumulating a Vector of delete-locations as you go using the insertElementAt(Integer, 0).) However you produce the Vector of initial-positions, you then need to convert the Vector of Integer objects to an array of int to create the event.

Notes:

  • Like the insertNodeInto method in the DefaultTreeModel class, insertElementAt appends to the Vector when the index matches the size of the vector. So you can use insertElementAt(Integer, 0) even when the vector is empty.
      To create a node changed event for the root node, specify the parent as null and the "child" index as zero.
    Parameters:
    source - the Object responsible for generating the event (typically the creator of the event object passes this for its value)
    path - an array of Object identifying the path to the parent of the modified item(s), where the first element of the array is the Object stored at the root node and the last element is the Object stored at the parent node
    childIndices - an array of int that specifies the index values of the removed items. The indices must be in sorted order, from lowest to highest
    children - an array of Object containing the inserted, removed, or changed objects
    See Also:
    TreePath

TreeModelEvent

public TreeModelEvent(Object source,
                      TreePath path,
                      int[] childIndices,
                      Object[] children)
Used to create an event when nodes have been changed, inserted, or removed, identifying the path to the parent of the modified items as a TreePath object. For more information on how to specify the indexes and objects, see TreeModelEvent(Object,Object[],int[],Object[]).
Parameters:
source - the Object responsible for generating the event (typically the creator of the event object passes this for its value)
path - a TreePath object that identifies the path to the parent of the modified item(s)
childIndices - an array of int that specifies the index values of the modified items
children - an array of Object containing the inserted, removed, or changed objects
See Also:
TreeModelEvent(Object,Object[],int[],Object[])

TreeModelEvent

public TreeModelEvent(Object source,
                      Object[] path)
Used to create an event when the node structure has changed in some way, identifying the path to the root of a modified subtree as an array of Objects. A structure change event might involve nodes swapping position, for example, or it might encapsulate multiple inserts and deletes in the subtree stemming from the node, where the changes may have taken place at different levels of the subtree.
Note:
JTree collapses all nodes under the specified node, so that only its immediate children are visible.
Parameters:
source - the Object responsible for generating the event (typically the creator of the event object passes this for its value)
path - an array of Object identifying the path to the root of the modified subtree, where the first element of the array is the object stored at the root node and the last element is the object stored at the changed node
See Also:
TreePath

TreeModelEvent

public TreeModelEvent(Object source,
                      TreePath path)
Used to create an event when the node structure has changed in some way, identifying the path to the root of the modified subtree as a TreePath object. For more information on this event specification, see TreeModelEvent(Object,Object[]).
Parameters:
source - the Object responsible for generating the event (typically the creator of the event object passes this for its value)
path - a TreePath object that identifies the path to the change. In the DefaultTreeModel, this object contains an array of user-data objects, but a subclass of TreePath could use some totally different mechanism -- for example, a node ID number
See Also:
TreeModelEvent(Object,Object[])
Method Detail

getTreePath

public TreePath getTreePath()
Returns the TreePath object identifying the changed node. Use getLastPathComponent on that object to get the data stored at that node.
Returns:
the TreePath object identifying the changed node
See Also:
TreePath.getLastPathComponent()

getPath

public Object[] getPath()
Convenience method to get the array of objects from the TreePath instance that this event wraps.
Returns:
an array of Objects, where the first Object is the one stored at the root and the last object is the one stored at the node identified by the path

getChildren

public Object[] getChildren()
Returns the objects that are children of the node identified by getPath at the locations specified by getChildIndices. If this is a removal event the returned objects are no longer children of the parent node.
Returns:
an array of Object containing the children specified by the event
See Also:
getPath(), getChildIndices()

getChildIndices

public int[] getChildIndices()
Returns the values of the child indexes. If this is a removal event the indexes point to locations in the initial list where items were removed. If it is an insert, the indices point to locations in the final list where the items were added. For node changes, the indices point to the locations of the modified nodes.
Returns:
an array of int containing index locations for the children specified by the event

toString

public String toString()
Returns a string that displays and identifies this object's properties.
Overrides:
toString in class EventObject
Returns:
a String representation of this object
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