Package org.apache.commons.configuration2.tree

Interface NodeHandler<T>

Type Parameters:
T - the type of the nodes this handler deals with
All Known Subinterfaces:
ReferenceNodeHandler
All Known Implementing Classes:
NodeHandlerDecorator
public interface NodeHandler<T>

Definition of an interface for accessing the data of a configuration node.

Hierarchical configurations can deal with arbitrary node structures. In order to obtain information about a specific node object, a so-called NodeHandler is used. The handler provides a number of methods for querying the internal state of a node in a read-only way.

  • Method Summary

    Modifier and Type
    Method
    Description
    Set<String>
    getAttributes(T node)
    Gets an unmodifiable set with the names of all attributes of the specified node.
    Object
    getAttributeValue(T node, String name)
    Gets the value of the specified attribute from the given node.
    T
    getChild(T node, int index)
    Gets the child with the given index of the specified node.
    List<T>
    getChildren(T node)
    Gets an unmodifiable list with all children of the specified node.
    List<T>
    getChildren(T node, String name)
    Gets an unmodifiable list of all children of the specified node with the given name.
    int
    getChildrenCount(T node, String name)
    Gets the number of children of the specified node with the given name.
    <C> List<T>
    getMatchingChildren(T node, NodeMatcher<C> matcher, C criterion)
    Gets an unmodifiable list of all children of the specified node which are matched by the passed in NodeMatcher against the provided criterion.
    <C> int
    getMatchingChildrenCount(T node, NodeMatcher<C> matcher, C criterion)
    Gets the number of children of the specified node which are matched by the given NodeMatcher.
    T
    getParent(T node)
    Gets the parent of the specified node.
    T
    getRootNode()
    Gets the root node of the underlying hierarchy.
    Object
    getValue(T node)
    Gets the value of the specified node.
    boolean
    hasAttributes(T node)
    Returns a flag whether the passed in node has any attributes.
    int
    indexOfChild(T parent, T child)
    Returns the index of the given child node in the list of children of its parent.
    boolean
    isDefined(T node)
    Checks whether the specified node is defined.
    String
    nodeName(T node)
    Returns the name of the specified node

  • Method Details

    • getAttributes

      Set<String> getAttributes(T node)
      Gets an unmodifiable set with the names of all attributes of the specified node.
      Parameters:
      node - the node
      Returns:
      a set with the names of all attributes of this node

    • getAttributeValue

      Object getAttributeValue(T node, String name)
      Gets the value of the specified attribute from the given node. If a concrete NodeHandler supports attributes with multiple values, result might be a collection.
      Parameters:
      node - the node
      name - the name of the attribute
      Returns:
      the value of this attribute

    • getChild

      T getChild(T node, int index)
      Gets the child with the given index of the specified node.
      Parameters:
      node - the node
      index - the index (0-based)
      Returns:
      the child with the given index

    • getChildren

      List<T> getChildren(T node)
      Gets an unmodifiable list with all children of the specified node.
      Parameters:
      node - the node
      Returns:
      a list with the child nodes of this node

    • getChildren

      List<T> getChildren(T node, String name)
      Gets an unmodifiable list of all children of the specified node with the given name.
      Parameters:
      node - the node
      name - the name of the desired child nodes
      Returns:
      a list with all children with the given name

    • getChildrenCount

      int getChildrenCount(T node, String name)
      Gets the number of children of the specified node with the given name. This method exists for performance reasons: for some node implementations it may be by far more efficient to count the children than to query a list of all children and determine its size. A concrete implementation can choose the most efficient way to determine the number of children. If a child name is passed in, only the children with this name are taken into account. If the name null is passed, the total number of children must be returned.
      Parameters:
      node - the node
      name - the name of the children in question (can be null for all children)
      Returns:
      the number of the selected children

    • getMatchingChildren

      <C> List<T> getMatchingChildren(T node, NodeMatcher<C> matcher, C criterion)
      Gets an unmodifiable list of all children of the specified node which are matched by the passed in NodeMatcher against the provided criterion. This method allows for advanced queries on a node's children.
      Type Parameters:
      C - the type of the criterion
      Parameters:
      node - the node
      matcher - the NodeMatcher defining filter criteria
      criterion - the criterion to be matched against; this object is passed to the NodeMatcher
      Returns:
      a list with all children matched by the matcher

    • getMatchingChildrenCount

      <C> int getMatchingChildrenCount(T node, NodeMatcher<C> matcher, C criterion)
      Gets the number of children of the specified node which are matched by the given NodeMatcher. This is a more generic version of getChildrenCount(Object, String). It allows checking for arbitrary filter conditions.
      Type Parameters:
      C - the type of the criterion
      Parameters:
      node - the node
      matcher - the NodeMatcher
      criterion - the criterion to be passed to the NodeMatcher
      Returns:
      the number of matched children

    • getParent

      T getParent(T node)
      Gets the parent of the specified node.
      Parameters:
      node - the node
      Returns:
      the parent node

    • getRootNode

      T getRootNode()
      Gets the root node of the underlying hierarchy.
      Returns:
      the current root node

    • getValue

      Object getValue(T node)
      Gets the value of the specified node.
      Parameters:
      node - the node
      Returns:
      the value of this node

    • hasAttributes

      boolean hasAttributes(T node)
      Returns a flag whether the passed in node has any attributes.
      Parameters:
      node - the node
      Returns:
      a flag whether this node has any attributes

    • indexOfChild

      int indexOfChild(T parent, T child)
      Returns the index of the given child node in the list of children of its parent. This method is the opposite operation of getChild(Object, int). This method returns 0 if the given node is the first child node with this name, 1 for the second child node and so on. If the node has no parent node or if it is an attribute, -1 is returned.
      Parameters:
      parent - the parent node
      child - a child node whose index is to be retrieved
      Returns:
      the index of this child node

    • isDefined

      boolean isDefined(T node)
      Checks whether the specified node is defined. Nodes are "defined" if they contain any data, e.g. a value, or attributes, or defined children.
      Parameters:
      node - the node to test
      Returns:
      a flag whether the passed in node is defined

    • nodeName

      String nodeName(T node)
      Returns the name of the specified node
      Parameters:
      node - the node
      Returns:
      the name of this node