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 and Description
Set<String>	getAttributes(T node) Returns an unmodifiable set with the names of all attributes of the specified node.
Object	getAttributeValue(T node, String name) Returns the value of the specified attribute from the given node.
T	getChild(T node, int index) Returns the child with the given index of the specified node.
List<T>	getChildren(T node) Returns an unmodifiable list with all children of the specified node.
List<T>	getChildren(T node, String name) Returns an unmodifiable list of all children of the specified node with the given name.
int	getChildrenCount(T node, String name) Returns the number of children of the specified node with the given name.
<C> List<T>	getMatchingChildren(T node, NodeMatcher<C> matcher, C criterion) Returns 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) Returns the number of children of the specified node which are matched by the given NodeMatcher.
T	getParent(T node) Returns the parent of the specified node.
T	getRootNode() Returns the root node of the underlying hierarchy.
Object	getValue(T node) Returns 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 Detail

nodeName

String nodeName(T node)

Returns the name of the specified node

Parameters:

node - the node

Returns:

the name of this node

getValue

Object getValue(T node)

Returns the value of the specified node.

Parameters:

node - the node

Returns:

the value of this node

getParent

T getParent(T node)

Returns the parent of the specified node.

Parameters:

node - the node

Returns:

the parent node

getChildren

List<T> getChildren(T node)

Returns 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)

Returns 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

getMatchingChildren

<C> List<T> getMatchingChildren(T node,
                                NodeMatcher<C> matcher,
                                C criterion)

Returns 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

getChild

T getChild(T node,
           int index)

Returns 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

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

getChildrenCount

int getChildrenCount(T node,
                     String name)

Returns 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

getMatchingChildrenCount

<C> int getMatchingChildrenCount(T node,
                                 NodeMatcher<C> matcher,
                                 C criterion)

Returns 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

getAttributes

Set<String> getAttributes(T node)

Returns 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

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

getAttributeValue

Object getAttributeValue(T node,
                         String name)

Returns 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

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

getRootNode

T getRootNode()

Returns the root node of the underlying hierarchy.

Returns:

the current root node