Class NodeDescendants

java.lang.Object
uk.ac.starlink.util.NodeDescendants
public class NodeDescendants extends Object
Represents the set of Nodes in the tree rooted at a particular DOM Node. The tree includes the root node.

This supports two ways of traversing the tree, either using an iterator, or providing an object which visits each node in the tree in turn.

Note that the iterator() and visitTree(NodeDescendants.Visitor) methods below share state -- namely the state which this object represents -- so you should not use simultaneously the result of two such method calls on the same object.

  • Field Details

    • SHOW_ALL

      public static final int SHOW_ALL
      Indicates that all nodes should be included in a traversal of, or iteration through, a tree. To visit only certain nodes, use one of the other SHOW... constants.

      Note: this mechanism is taken from the DOM2 Traversal specification, though it is not an implementation of that set of interfaces. As noted there, not all of the SHOW... values are useful, since not all of the associated Node types can appear as descendants of a Node, othe than in rather special circumstances. The constants are included here for completeness, however.

      See Also:

    • SHOW_ELEMENT

      public static final int SHOW_ELEMENT
      See Also:

    • SHOW_ATTRIBUTE

      public static final int SHOW_ATTRIBUTE
      See Also:

    • SHOW_TEXT

      public static final int SHOW_TEXT
      See Also:

    • SHOW_CDATA_SECTION

      public static final int SHOW_CDATA_SECTION
      See Also:

    • SHOW_ENTITY_REFERENCE

      public static final int SHOW_ENTITY_REFERENCE
      See Also:

    • SHOW_ENTITY

      public static final int SHOW_ENTITY
      See Also:

    • SHOW_PROCESSING_INSTRUCTION

      public static final int SHOW_PROCESSING_INSTRUCTION
      See Also:

    • SHOW_COMMENT

      public static final int SHOW_COMMENT
      See Also:

    • SHOW_DOCUMENT

      public static final int SHOW_DOCUMENT
      See Also:

    • SHOW_DOCUMENT_TYPE

      public static final int SHOW_DOCUMENT_TYPE
      See Also:

    • SHOW_DOCUMENT_FRAGMENT

      public static final int SHOW_DOCUMENT_FRAGMENT
      See Also:

    • SHOW_NOTATION

      public static final int SHOW_NOTATION
      See Also:

  • Constructor Details

    • NodeDescendants

      public NodeDescendants(Node node)
      Creates a new NodeDescendant object. Equivalent to NodeDescendant(node, SHOW_ALL).
      Parameters:
      node - the node which is to be the root of the tree

    • NodeDescendants

      public NodeDescendants(Node node, int whatToShow)
      Creates a new NodeDescendant object. This represents the set of Nodes in the tree rooted at the given Node.

      You can configure the set to include only certain nodes. If the whatToShow parameter is given as SHOW_ALL, then all nodes are returned. If the parameter has one of the other SHOW_... values, or more than one or'ed together (using |), then only the indicated node types are included in the set, and returned by any iterator or examined by any visitor.

      For example, if you create the NodeDescendant using the constructor: 

      NodeDescendants tree = new NodeDescendants
    (mynode, NodeDescendants.SHOW_ALL);
      (which is equivalent to the NodeDescendants(Node) constructor), then the set represents all the nodes in the tree which are reachable from the node mynode by the getFirstChild and similar methods. If, however, the object was constructed with 
      NodeDescendants tree = new NodeDescendants
    (mynode, 
    NodeDescendants.SHOW_TEXT|NodeDescendants.SHOW_CDATA_SECTION);
      then all Text and CDATA nodes would be included in the set, and only these would be returned by the iterator or visited by the visitor.
      Parameters:
      node - the node which is to be the root of the tree
      whatToShow - code indicating which node types should be included in the set

  • Method Details

    • reset

      public void reset()
      Sets the object back to its initial state. This allows you to extract a second iterator either after an earlier one has finished, or before.

    • reset

      public void reset(int whatToShow)
      Sets the object back to its initial state, but with a (possibly) different constraint on which nodes are included in the set.
      Parameters:
      whatToShow - code indicating which node types should be included in the set. See NodeDescendants(Node,int)

    • visitTree

      public Object visitTree(NodeDescendants.Visitor v)
      Visits each of the nodes in the tree. This method iterates through all the descendants of the given node, starting with that node, and presents each of them to the given NodeVisitor. If that object's visitNode method returns non-null, then the traversal is stopped and the returned object immediately returned as the value of this method. If the visitNode method always returns null and so the traversal completes, then the method returns null also.
      Parameters:
      v - a visitor which has each node presented to it in turn

    • iterator

      public Iterator<Node> iterator()
      Obtains an iterator which iterates over the nodes in the set of descendants. The traversal happens in depth-first order.
      Returns:
      an iterator which returns in turn the given node, then all of its descendants.

Copyright © 2026 Central Laboratory of the Research Councils. All Rights Reserved.