org.apache.commons.configuration2.tree

Class NodeSelector

java.lang.Object

org.apache.commons.configuration2.tree.NodeSelector

public class NodeSelector
extends Object

A class for selecting a specific node based on a key or a set of keys.

An instance of this class is initialized with the key of a node. It is also possible to concatenate multiple keys - e.g. if a sub key is to be constructed from another sub key. NodeSelector provides the select() method which evaluates the wrapped keys on a specified root node and returns the resulting unique target node. The class expects that the key(s) stored in an instance select exactly one target node. If this is not the case, result is null indicating that the selection criteria are not sufficient.

Implementation node: Instances of this class are immutable. They can be shared between arbitrary components.

Since:

2.0

Constructor Summary

Constructors

Constructor and Description
NodeSelector(String key) Creates a new instance of NodeSelector and initializes it with the key to the target node.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj) Compares this object with another one.
int	hashCode() Returns a hash code for this object.
ImmutableNode	select(ImmutableNode root, NodeKeyResolver<ImmutableNode> resolver, NodeHandler<ImmutableNode> handler) Applies this NodeSelector on the specified root node.
NodeSelector	subSelector(String subKey) Creates a sub NodeSelector object which uses the key(s) of this selector plus the specified key as selection criteria.
String	toString() Returns a string representation for this object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

NodeSelector

public NodeSelector(String key)

Creates a new instance of NodeSelector and initializes it with the key to the target node.

Parameters:

key - the key

Method Detail

select

public ImmutableNode select(ImmutableNode root,
                            NodeKeyResolver<ImmutableNode> resolver,
                            NodeHandler<ImmutableNode> handler)

Applies this NodeSelector on the specified root node. This method applies the selection criteria stored in this object and tries to determine a single target node. If this is successful, the target node is returned. Otherwise, result is null.

Parameters:

root - the root node on which to apply this selector

resolver - the NodeKeyResolver

handler - the NodeHandler

Returns:

the selected target node or null

subSelector

public NodeSelector subSelector(String subKey)

Creates a sub NodeSelector object which uses the key(s) of this selector plus the specified key as selection criteria. This is useful when another selection is to be performed on the results of a first selector.

Parameters:

subKey - the additional key for the sub selector

Returns:

the sub NodeSelector instance

equals

public boolean equals(Object obj)

Compares this object with another one. Two instances of NodeSelector are considered equal if they have the same keys as selection criteria.

Overrides:

equals in class Object

Parameters:

obj - the object to be compared

Returns:

a flag whether these objects are equal

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class Object

Returns:

a hash code

toString

public String toString()

Returns a string representation for this object. This string contains the keys to be used as selection criteria.

Overrides:

toString in class Object

Returns:

a string for this object