Class NodeTreeWalker

java.lang.Object
org.htmlparser.util.NodeTreeWalker
All Implemented Interfaces:
NodeIterator

public class NodeTreeWalker extends Object implements NodeIterator
A class for walking a tree of Node objects, in either a depth-first or breadth-first manner. The following two diagrams show the represent tree traversal with the two different methods.
Depth-first traversal Breadth-first traversal
Author:
ian_macfarlane
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected Node
    The current Node element, which will be a child of the root Node, or null.
    protected boolean
    Whether the tree traversal method used is depth-first (default) or breadth-first.
    protected int
    The maximum depth (child-parent links) from which this NodeTreeWalker may be removed from the root Node.
    protected Node
    The next Node element after the current Node element.
    protected Node
    The root Node element which defines the scope of the current tree to walk.
  • Constructor Summary

    Constructors
    Constructor
    Description
    NodeTreeWalker(Node rootNode)
    Creates a new instance of NodeTreeWalker using depth-first tree traversal, without limits on how deep it may traverse.
    NodeTreeWalker(Node rootNode, boolean depthFirst)
    Creates a new instance of NodeTreeWalker using the specified type of tree traversal, without limits on how deep it may traverse.
    NodeTreeWalker(Node rootNode, boolean depthFirst, int maxDepth)
    Creates a new instance of NodeTreeWalker using the specified type of tree traversal and maximum depth from the root Node to traverse.
  • Method Summary

    Modifier and Type
    Method
    Description
    Get the Node in the tree that the NodeTreeWalker is current at.
    int
    Get the number of places down that the current Node is from the root Node.
    int
    The maximum depth (number of child-parent links) below the root Node that this NodeTreeWalker may traverse.
    protected Node
    Traverses to the next Node from the current Node using breadth-first tree traversal
    protected Node
    Traverses to the next Node from the current Node using depth-first tree traversal
    Get the root Node that defines the scope of the tree to traverse.
    boolean
    Returns whether or not there are more nodes available based on the current configuration of this NodeTreeWalker.
    protected void
    initRootNode(Node rootNode)
    Sets the root Node to be the given Node.
    boolean
    Whether the NodeTreeWalker is currently set to use depth-first or breadth-first tree traversal.
    Traverses to the next Node from the current Node, using either depth-first or breadth-first tree traversal as appropriate.
    void
    Removes any restrictions in place that prevent this NodeTreeWalker from traversing beyond a certain depth.
    void
    Resets the current position in the tree, such that calling nextNode() will return the first Node again.
    void
    Sets the current Node as the root Node.
    void
    setDepthFirst(boolean depthFirst)
    Sets whether the NodeTreeWalker should use depth-first or breadth-first tree traversal.
    void
    setRootNode(Node rootNode)
    Sets the specified Node as the root Node.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • mRootNode

      protected Node mRootNode
      The root Node element which defines the scope of the current tree to walk.
    • mCurrentNode

      protected Node mCurrentNode
      The current Node element, which will be a child of the root Node, or null.
    • mNextNode

      protected Node mNextNode
      The next Node element after the current Node element. Stored for internal use only.
    • mMaxDepth

      protected int mMaxDepth
      The maximum depth (child-parent links) from which this NodeTreeWalker may be removed from the root Node. A value of -1 indicates that there is no depth restriction.
    • mDepthFirst

      protected boolean mDepthFirst
      Whether the tree traversal method used is depth-first (default) or breadth-first.
  • Constructor Details

    • NodeTreeWalker

      public NodeTreeWalker(Node rootNode)
      Creates a new instance of NodeTreeWalker using depth-first tree traversal, without limits on how deep it may traverse.
      Parameters:
      rootNode - Node The Node to set as the root of the tree.
      Throws:
      NullPointerException - if root Node is null.
    • NodeTreeWalker

      public NodeTreeWalker(Node rootNode, boolean depthFirst)
      Creates a new instance of NodeTreeWalker using the specified type of tree traversal, without limits on how deep it may traverse.
      Parameters:
      rootNode - The Node to set as the root of the tree.
      depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.
      Throws:
      NullPointerException - if rootNode is null.
    • NodeTreeWalker

      public NodeTreeWalker(Node rootNode, boolean depthFirst, int maxDepth)
      Creates a new instance of NodeTreeWalker using the specified type of tree traversal and maximum depth from the root Node to traverse.
      Parameters:
      rootNode - The Node to set as the root of the tree.
      depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.
      maxDepth - The maximum depth from the root Node that this NodeTreeWalker may traverse. This must be > 0 or equal to -1.
      Throws:
      NullPointerException - if rootNode is null.
      IllegalArgumentException - maxDepth is not > 0 or equal to -1.
  • Method Details

    • isDepthFirst

      public boolean isDepthFirst()
      Whether the NodeTreeWalker is currently set to use depth-first or breadth-first tree traversal.
      Returns:
      True if depth-first tree-traversal is used, or false if breadth-first tree-traversal is being used.
    • setDepthFirst

      public void setDepthFirst(boolean depthFirst)
      Sets whether the NodeTreeWalker should use depth-first or breadth-first tree traversal.
      Parameters:
      depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.
    • getMaxDepth

      public int getMaxDepth()
      The maximum depth (number of child-parent links) below the root Node that this NodeTreeWalker may traverse.
      Returns:
      The maximum depth that this NodeTreeWalker can traverse to.
    • removeMaxDepthRestriction

      public void removeMaxDepthRestriction()
      Removes any restrictions in place that prevent this NodeTreeWalker from traversing beyond a certain depth.
    • getRootNode

      public Node getRootNode()
      Get the root Node that defines the scope of the tree to traverse.
      Returns:
      The root Node.
    • getCurrentNode

      public Node getCurrentNode()
      Get the Node in the tree that the NodeTreeWalker is current at.
      Returns:
      The current Node.
    • setCurrentNodeAsRootNode

      public void setCurrentNodeAsRootNode() throws NullPointerException
      Sets the current Node as the root Node. Resets the current position in the tree.
      Throws:
      NullPointerException - if the current Node is null (i.e. if the tree traversal has not yet begun).
    • setRootNode

      public void setRootNode(Node rootNode) throws NullPointerException
      Sets the specified Node as the root Node. Resets the current position in the tree.
      Parameters:
      rootNode - The Node to set as the root of the tree.
      Throws:
      NullPointerException - if rootNode is null.
    • reset

      public void reset()
      Resets the current position in the tree, such that calling nextNode() will return the first Node again.
    • nextNode

      public Node nextNode()
      Traverses to the next Node from the current Node, using either depth-first or breadth-first tree traversal as appropriate.
      Specified by:
      nextNode in interface NodeIterator
      Returns:
      The next Node from the current Node.
    • getCurrentNodeDepth

      public int getCurrentNodeDepth()
      Get the number of places down that the current Node is from the root Node. Returns 1 if current Node is a child of the root Node. Returns 0 if this NodeTreeWalker has not yet traversed to any Nodes.
      Returns:
      The depth the current Node is from the root Node.
    • hasMoreNodes

      public boolean hasMoreNodes()
      Returns whether or not there are more nodes available based on the current configuration of this NodeTreeWalker.
      Specified by:
      hasMoreNodes in interface NodeIterator
      Returns:
      True if there are more Nodes available, based on the current configuration, or false otherwise.
    • initRootNode

      protected void initRootNode(Node rootNode) throws NullPointerException
      Sets the root Node to be the given Node. Resets the current position in the tree.
      Parameters:
      rootNode - The Node to set as the root of the tree.
      Throws:
      NullPointerException - if rootNode is null.
    • getNextNodeDepthFirst

      protected Node getNextNodeDepthFirst()
      Traverses to the next Node from the current Node using depth-first tree traversal
      Returns:
      The next Node from the current Node using depth-first tree traversal.
    • getNextNodeBreadthFirst

      protected Node getNextNodeBreadthFirst()
      Traverses to the next Node from the current Node using breadth-first tree traversal
      Returns:
      The next Node from the current Node using breadth-first tree traversal.