Package org.apache.commons.configuration2.tree

# Class NodeHandlerDecorator<T>

java.lang.Object
org.apache.commons.configuration2.tree.NodeHandlerDecorator<T>

Type Parameters:
  `T` - the type of the nodes supported by this handler

All Implemented Interfaces:
  `NodeHandler<T>`

public abstract class NodeHandlerDecorator<T> extends Object implements NodeHandler<T>

An abstract base class for decorators of a `NodeHandler`.

This class implements all methods of the `NodeHandler` interface by delegating to another instance. This is convenient if specific functionality of a `NodeHandler` is to be adapted for a special use case. Concrete sub classes have to implement the `getDecoratedNodeHandler()` method to provide the underlying handler.

Since:
  2.0

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `NodeHandlerDecorator()`
  Constructs a new instance.

- ## 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.
  `protected abstract NodeHandler<T>`
  `getDecoratedNodeHandler()`
  Gets the `NodeHandler` object that is decorated by this instance.
  `<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

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### NodeHandlerDecorator

    public NodeHandlerDecorator()
    Constructs a new instance.

- ## Method Details

  - ### getAttributes

    public Set<String> getAttributes(T node)
    Description copied from interface: `NodeHandler`
    Gets an unmodifiable set with the names of all attributes of the specified node.
    Specified by:
      `getAttributes` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      a set with the names of all attributes of this node

  - ### getAttributeValue

    public Object getAttributeValue(T node, String name)
    Description copied from interface: `NodeHandler`
    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.
    Specified by:
      `getAttributeValue` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
      `name` - the name of the attribute
    Returns:
      the value of this attribute

  - ### getChild

    public T getChild(T node, int index)
    Description copied from interface: `NodeHandler`
    Gets the child with the given index of the specified node.
    Specified by:
      `getChild` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
      `index` - the index (0-based)
    Returns:
      the child with the given index

  - ### getChildren

    public List<T> getChildren(T node)
    Description copied from interface: `NodeHandler`
    Gets an unmodifiable list with all children of the specified node.
    Specified by:
      `getChildren` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      a list with the child nodes of this node

  - ### getChildren

    public List<T> getChildren(T node, String name)
    Description copied from interface: `NodeHandler`
    Gets an unmodifiable list of all children of the specified node with the given name.
    Specified by:
      `getChildren` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
      `name` - the name of the desired child nodes
    Returns:
      a list with all children with the given name

  - ### getChildrenCount

    public int getChildrenCount(T node, String name)
    Description copied from interface: `NodeHandler`
    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.
    Specified by:
      `getChildrenCount` in interface `NodeHandler<T>`
    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

  - ### getDecoratedNodeHandler

    protected abstract NodeHandler<T> getDecoratedNodeHandler()
    Gets the `NodeHandler` object that is decorated by this instance. All method calls are delegated to this object.
    Returns:
      the decorated `NodeHandler`

  - ### getMatchingChildren

    public <C> List<T> getMatchingChildren(T node, NodeMatcher<C> matcher, C criterion)
    Description copied from interface: `NodeHandler`
    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.
    Specified by:
      `getMatchingChildren` in interface `NodeHandler<T>`
    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

    public <C> int getMatchingChildrenCount(T node, NodeMatcher<C> matcher, C criterion)
    Description copied from interface: `NodeHandler`
    Gets the number of children of the specified node which are matched by the given `NodeMatcher`. This is a more generic version of `NodeHandler.getChildrenCount(Object, String)`. It allows checking for arbitrary filter conditions.
    Specified by:
      `getMatchingChildrenCount` in interface `NodeHandler<T>`
    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

    public T getParent(T node)
    Description copied from interface: `NodeHandler`
    Gets the parent of the specified node.
    Specified by:
      `getParent` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      the parent node

  - ### getRootNode

    public T getRootNode()
    Description copied from interface: `NodeHandler`
    Gets the root node of the underlying hierarchy.
    Specified by:
      `getRootNode` in interface `NodeHandler<T>`
    Returns:
      the current root node

  - ### getValue

    public Object getValue(T node)
    Description copied from interface: `NodeHandler`
    Gets the value of the specified node.
    Specified by:
      `getValue` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      the value of this node

  - ### hasAttributes

    public boolean hasAttributes(T node)
    Description copied from interface: `NodeHandler`
    Returns a flag whether the passed in node has any attributes.
    Specified by:
      `hasAttributes` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      a flag whether this node has any attributes

  - ### indexOfChild

    public int indexOfChild(T parent, T child)
    Description copied from interface: `NodeHandler`
    Returns the index of the given child node in the list of children of its parent. This method is the opposite operation of `NodeHandler.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.
    Specified by:
      `indexOfChild` in interface `NodeHandler<T>`
    Parameters:
      `parent` - the parent node
      `child` - a child node whose index is to be retrieved
    Returns:
      the index of this child node

  - ### isDefined

    public boolean isDefined(T node)
    Description copied from interface: `NodeHandler`
    Checks whether the specified node is defined. Nodes are "defined" if they contain any data, for example a value, or attributes, or defined children.
    Specified by:
      `isDefined` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node to test
    Returns:
      a flag whether the passed in node is defined

  - ### nodeName

    public String nodeName(T node)
    Description copied from interface: `NodeHandler`
    Returns the name of the specified node
    Specified by:
      `nodeName` in interface `NodeHandler<T>`
    Parameters:
      `node` - the node
    Returns:
      the name of this node