public interface TreeWalker
TreeWalker objects are used to navigate a document tree or 
 subtree using the view of the document defined by their 
 whatToShow flags and filter (if any). Any function which 
 performs navigation using a TreeWalker will automatically 
 support any view defined by a TreeWalker.
 Omitting nodes from the logical view of a subtree can result in a 
 structure that is substantially different from the same subtree in the 
 complete, unfiltered document. Nodes that are siblings in the 
 TreeWalker view may be children of different, widely 
 separated nodes in the original view. For instance, consider a 
 NodeFilter that skips all nodes except for Text nodes and 
 the root node of a document. In the logical view that results, all text 
 nodes will be siblings and appear as direct children of the root node, no 
 matter how deeply nested the structure of the original document.
 
See also the Document Object Model (DOM) Level 2 Traversal and Range Specification.
| Modifier and Type | Method and Description | 
|---|---|
| Node | firstChild()Moves the  TreeWalkerto the first visible child of the 
 current node, and returns the new node. | 
| Node | getCurrentNode()The node at which the  TreeWalkeris currently positioned. | 
| boolean | getExpandEntityReferences()The value of this flag determines whether the children of entity 
 reference nodes are visible to the  TreeWalker. | 
| NodeFilter | getFilter()The filter used to screen nodes. | 
| Node | getRoot()The  rootnode of theTreeWalker, as specified 
 when it was created. | 
| int | getWhatToShow()This attribute determines which node types are presented via the 
  TreeWalker. | 
| Node | lastChild()Moves the  TreeWalkerto the last visible child of the 
 current node, and returns the new node. | 
| Node | nextNode()Moves the  TreeWalkerto the next visible node in document 
 order relative to the current node, and returns the new node. | 
| Node | nextSibling()Moves the  TreeWalkerto the next sibling of the current 
 node, and returns the new node. | 
| Node | parentNode()Moves to and returns the closest visible ancestor node of the current 
 node. | 
| Node | previousNode()Moves the  TreeWalkerto the previous visible node in 
 document order relative to the current node, and returns the new 
 node. | 
| Node | previousSibling()Moves the  TreeWalkerto the previous sibling of the 
 current node, and returns the new node. | 
| void | setCurrentNode(Node currentNode)The node at which the  TreeWalkeris currently positioned. | 
Node getRoot()
root node of the TreeWalker, as specified 
 when it was created.int getWhatToShow()
TreeWalker. The available set of constants is defined in 
 the NodeFilter interface.  Nodes not accepted by 
 whatToShow will be skipped, but their children may still 
 be considered. Note that this skip takes precedence over the filter, 
 if any.NodeFilter getFilter()
boolean getExpandEntityReferences()
TreeWalker. If false, 
 these children  and their descendants will be rejected. Note that 
 this rejection takes precedence over whatToShow and the 
 filter, if any. 
 whatToShow flags to hide the entity reference node 
 and set expandEntityReferences to true when creating the 
 TreeWalker. To produce a view of the document that has 
 entity reference nodes but no entity expansion, use the 
 whatToShow flags to show the entity reference node and 
 set expandEntityReferences to false.Node getCurrentNode()
TreeWalker is currently positioned.
 TreeWalker's associated filter. 
 currentNode may also be explicitly set to any node, 
 whether or not it is within the subtree specified by the 
 root node or would be accepted by the filter and 
 whatToShow flags. Further traversal occurs relative to 
 currentNode even if it is not part of the current view, 
 by applying the filters in the requested direction; if no traversal 
 is possible, currentNode is not changed.void setCurrentNode(Node currentNode) throws DOMException
TreeWalker is currently positioned.
 TreeWalker's associated filter. 
 currentNode may also be explicitly set to any node, 
 whether or not it is within the subtree specified by the 
 root node or would be accepted by the filter and 
 whatToShow flags. Further traversal occurs relative to 
 currentNode even if it is not part of the current view, 
 by applying the filters in the requested direction; if no traversal 
 is possible, currentNode is not changed.DOMException - NOT_SUPPORTED_ERR: Raised if an attempt is made to set 
   currentNode to null.Node parentNode()
parentNode attempts to step 
 upward from the TreeWalker's root node, or 
 if it fails to find a visible ancestor node, this method retains the 
 current position and returns null.null if the current node 
   has no parent  in the TreeWalker's logical view.Node firstChild()
TreeWalker to the first visible child of the 
 current node, and returns the new node. If the current node has no 
 visible children, returns null, and retains the current 
 node.null if the current node has no 
   visible children  in the TreeWalker's logical view.Node lastChild()
TreeWalker to the last visible child of the 
 current node, and returns the new node. If the current node has no 
 visible children, returns null, and retains the current 
 node.null if the current node has no 
   children  in the TreeWalker's logical view.Node previousSibling()
TreeWalker to the previous sibling of the 
 current node, and returns the new node. If the current node has no 
 visible previous sibling, returns null, and retains the 
 current node.null if the current node has no 
   previous sibling.  in the TreeWalker's logical view.Node nextSibling()
TreeWalker to the next sibling of the current 
 node, and returns the new node. If the current node has no visible 
 next sibling, returns null, and retains the current node.null if the current node has no 
   next sibling.  in the TreeWalker's logical view.Node previousNode()
TreeWalker to the previous visible node in 
 document order relative to the current node, and returns the new 
 node. If the current node has no previous node,  or if the search for 
 previousNode attempts to step upward from the 
 TreeWalker's root node,  returns 
 null, and retains the current node.null if the current node has no 
   previous node  in the TreeWalker's logical view.Node nextNode()
TreeWalker to the next visible node in document 
 order relative to the current node, and returns the new node. If the 
 current node has no next node, or if the search for nextNode attempts 
 to step upward from the TreeWalker's root 
 node, returns null, and retains the current node.null if the current node has no 
   next node  in the TreeWalker's logical view.Copyright © 1999-2022 The Apache Software Foundation. All Rights Reserved.