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org.dom4j

Interface Node

All Superinterfaces:
Cloneable
Known Subinterfaces:
Attribute, Branch, CDATA, CharacterData, Comment, Document, DocumentType, Element, Entity, ProcessingInstruction, Text
Known Implementing Classes:
DatatypeAttribute, DatatypeElement, IndexedElement, Namespace, NonLazyElement, UserDataAttribute, UserDataElement
public interface Node
extends Cloneable
Node defines the polymorphic behavior for all XML nodes in a dom4j tree.

A node can be output as its XML format, can be detached from its position in a document and can have XPath expressions evaluated on itself.

A node may optionally support the parent relationship and may be read only.

Version:
$Revision: 1.31 $
Author:
James Strachan
See Also:
supportsParent(), isReadOnly()

Field Summary

static short
ANY_NODE
Matches Element nodes
static short
ATTRIBUTE_NODE
Matches elements nodes
static short
CDATA_SECTION_NODE
Matches elements nodes
static short
COMMENT_NODE
Matches Comments nodes
static short
DOCUMENT_NODE
Matches Document nodes
static short
DOCUMENT_TYPE_NODE
Matches DocumentType nodes
static short
ELEMENT_NODE
Matches Element nodes
static short
ENTITY_REFERENCE_NODE
Matches elements nodes
static short
MAX_NODE_TYPE
The maximum number of node types for sizing purposes
static short
NAMESPACE_NODE
Matchs a Namespace Node - NOTE this differs from DOM
static short
PROCESSING_INSTRUCTION_NODE
Matches ProcessingInstruction
static short
TEXT_NODE
Matches elements nodes
static short
UNKNOWN_NODE
Does not match any valid node

Method Summary

void
accept(Visitor visitor)
accept is the method used in the Visitor Pattern.
String
asXML()
asXML returns the textual XML representation of this node.
Node
asXPathResult(Element parent)
asXPathResult returns a version of this node which is capable of being an XPath result.
Object
clone()
clone will return a deep clone or if this node is read-only then clone will return the same instance.
XPath
createXPath(String xpathExpression)
createXPath creates an XPath object for the given xpathExpression.
Node
detach()
Removes this node from its parent if there is one.
Document
getDocument()
getDocument returns the Document that this Node is part of if this node supports the parent relationship.
String
getName()
getName returns the name of this node.
short
getNodeType()
Returns the code according to the type of node.
String
getNodeTypeName()
DOCUMENT ME!
Element
getParent()
getParent returns the parent Element if this node supports the parent relationship or null if it is the root element or does not support the parent relationship.
String
getPath()
Returns the XPath expression which will return a node set containing the given node such as /a/b/@c.
String
getPath(Element context)
Returns the relative XPath expression which will return a node set containing the given node such as a/b/@c.
String
getStringValue()
Returns the XPath string-value of this node.
String
getText()
Returns the text of this node.
String
getUniquePath()
Returns the XPath expression which will return a nodeset of one node which is the current node.
String
getUniquePath(Element context)
Returns the relative unique XPath expression from the given context which will return a nodeset of one node which is the current node.
boolean
hasContent()
hasContent returns true if this node is a Branch (either an Element or a Document) and it contains at least one content node such as a child Element or Text node.
boolean
isReadOnly()
isReadOnly returns true if this node is read only and cannot be modified.
boolean
matches(String xpathExpression)
matches returns true if evaluating the given XPath expression on this node returns a non-empty node set containing this node.
Number
numberValueOf(String xpathExpression)
numberValueOf evaluates an XPath expression and returns the numeric value of the XPath expression if the XPath expression results in a number, or null if the result is not a number.
List
selectNodes(String xpathExpression)
selectNodes evaluates an XPath expression and returns the result as a List of Node instances or String instances depending on the XPath expression.
List
selectNodes(String xpathExpression, String comparisonXPathExpression)
selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
List
selectNodes(String xpathExpression, String comparisonXPathExpression, boolean removeDuplicates)
selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
Object
selectObject(String xpathExpression)
selectObject evaluates an XPath expression and returns the result as an Object.
Node
selectSingleNode(String xpathExpression)
selectSingleNode evaluates an XPath expression and returns the result as a single Node instance.
void
setDocument(Document document)
setDocument sets the document of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.
void
setName(String name)
Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
void
setParent(Element parent)
setParent sets the parent relationship of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.
void
setText(String text)
Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
boolean
supportsParent()
supportsParent returns true if this node supports the parent relationship.
String
valueOf(String xpathExpression)
valueOf evaluates an XPath expression and returns the textual representation of the results the XPath string-value of this node.
void
write(Writer writer)
write writes this node as the default XML notation for this node.

Field Details

ANY_NODE

public static final short ANY_NODE
Matches Element nodes
Field Value:
0

ATTRIBUTE_NODE

public static final short ATTRIBUTE_NODE
Matches elements nodes
Field Value:
2

CDATA_SECTION_NODE

public static final short CDATA_SECTION_NODE
Matches elements nodes
Field Value:
4

COMMENT_NODE

public static final short COMMENT_NODE
Matches Comments nodes
Field Value:
8

DOCUMENT_NODE

public static final short DOCUMENT_NODE
Matches Document nodes
Field Value:
9

DOCUMENT_TYPE_NODE

public static final short DOCUMENT_TYPE_NODE
Matches DocumentType nodes
Field Value:
10

ELEMENT_NODE

public static final short ELEMENT_NODE
Matches Element nodes
Field Value:
1

ENTITY_REFERENCE_NODE

public static final short ENTITY_REFERENCE_NODE
Matches elements nodes
Field Value:
5

MAX_NODE_TYPE

public static final short MAX_NODE_TYPE
The maximum number of node types for sizing purposes
Field Value:
14

NAMESPACE_NODE

public static final short NAMESPACE_NODE
Matchs a Namespace Node - NOTE this differs from DOM
Field Value:
13

PROCESSING_INSTRUCTION_NODE

public static final short PROCESSING_INSTRUCTION_NODE
Matches ProcessingInstruction
Field Value:
7

TEXT_NODE

public static final short TEXT_NODE
Matches elements nodes
Field Value:
3

UNKNOWN_NODE

public static final short UNKNOWN_NODE
Does not match any valid node
Field Value:
14

Method Details

accept

public void accept(Visitor visitor)
accept is the method used in the Visitor Pattern.
Parameters:
visitor - is the visitor in the Visitor Pattern

asXML

public String asXML()
asXML returns the textual XML representation of this node.
Returns:
the XML representation of this node

asXPathResult

public Node asXPathResult(Element parent)
asXPathResult returns a version of this node which is capable of being an XPath result. The result of an XPath expression should always support the parent relationship, whether the original XML tree was singly or doubly linked. If the node does not support the parent relationship then a new node will be created which is linked to its parent and returned.
Parameters:
parent - DOCUMENT ME!
Returns:
a Node which supports the parent relationship

clone

public Object clone()
clone will return a deep clone or if this node is read-only then clone will return the same instance.
Returns:
a deep clone of myself or myself if I am read only.

createXPath

public XPath createXPath(String xpathExpression)
            throws InvalidXPathException
createXPath creates an XPath object for the given xpathExpression. The XPath object allows the variable context to be specified.
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
an XPath object represeting the given expression
Throws:
InvalidXPathException - if the XPath expression is invalid

detach

public Node detach()
Removes this node from its parent if there is one. If this node is the root element of a document then it is removed from the document as well.

This method is useful if you want to remove a node from its source document and add it to another document. For example Node node = ...; Element someOtherElement = ...; someOtherElement.add( node.detach() );

Returns:
the node that has been removed from its parent node if any and its document if any.

getDocument

public Document getDocument()
getDocument returns the Document that this Node is part of if this node supports the parent relationship.

This method is an optional feature and may not be supported for all Node implementations.

Returns:
the document of this node or null if this feature is not supported or the node is not associated with a Document

getName

public String getName()
getName returns the name of this node. This is the XML local name of the element, attribute, entity or processing instruction. For CDATA and Text nodes this method will return null.
Returns:
the XML name of this node

getNodeType

public short getNodeType()
Returns the code according to the type of node. This makes processing nodes polymorphically much easier as the switch statement can be used instead of multiple if (instanceof) statements.
Returns:
a W3C DOM complient code for the node type such as ELEMENT_NODE or ATTRIBUTE_NODE

getNodeTypeName

public String getNodeTypeName()
DOCUMENT ME!
Returns:
the name of the type of node such as "Document", "Element", "Attribute" or "Text"

getParent

public Element getParent()
getParent returns the parent Element if this node supports the parent relationship or null if it is the root element or does not support the parent relationship.

This method is an optional feature and may not be supported for all Node implementations.

Returns:
the parent of this node or null if it is the root of the tree or the parent relationship is not supported.

getPath

public String getPath()
Returns the XPath expression which will return a node set containing the given node such as /a/b/@c. No indexing will be used to restrict the path if multiple elements with the same name occur on the path.
Returns:
the XPath expression which will return a nodeset containing at least this node.

getPath

public String getPath(Element context)
Returns the relative XPath expression which will return a node set containing the given node such as a/b/@c. No indexing will be used to restrict the path if multiple elements with the same name occur on the path.
Parameters:
context - is the parent context from which the relative path should start. If the context is null or the context is not an ancestor of this node then the path will be absolute and start from the document and so begin with the '/' character.
Returns:
the XPath expression relative to the given context which will return a nodeset containing at least this node.

getStringValue

public String getStringValue()
Returns the XPath string-value of this node. The behaviour of this method is defined in the XPath specification .
Returns:
the text from all the child Text and Element nodes appended together.

getText

public String getText()
Returns the text of this node.
Returns:
the text for this node.

getUniquePath

public String getUniquePath()
Returns the XPath expression which will return a nodeset of one node which is the current node. This method will use the XPath index operator to restrict the path if multiple elements with the same name occur on the path.
Returns:
the XPath expression which will return a nodeset containing just this node.

getUniquePath

public String getUniquePath(Element context)
Returns the relative unique XPath expression from the given context which will return a nodeset of one node which is the current node. This method will use the XPath index operator to restrict the path if multiple elements with the same name occur on the path.
Parameters:
context - is the parent context from which the path should start. If the context is null or the context is not an ancestor of this node then the path will start from the document and so begin with the '/' character.
Returns:
the XPath expression relative to the given context which will return a nodeset containing just this node.

hasContent

public boolean hasContent()
hasContent returns true if this node is a Branch (either an Element or a Document) and it contains at least one content node such as a child Element or Text node.
Returns:
true if this Node is a Branch with a nodeCount() of one or more.

isReadOnly

public boolean isReadOnly()
isReadOnly returns true if this node is read only and cannot be modified. Any attempt to modify a read-only Node will result in an UnsupportedOperationException being thrown.
Returns:
true if this Node is read only and cannot be modified otherwise false.

matches

public boolean matches(String xpathExpression)
matches returns true if evaluating the given XPath expression on this node returns a non-empty node set containing this node.

This method does not behave like the <xsl:if> element - if you want that behaviour, to evaluate if an XPath expression matches something, then you can use the following code to be equivalent... if ( node.selectSingleNode( "/some/path" ) != nulll )

Parameters:
xpathExpression - is an XPath expression
Returns:
true if this node is returned by the given XPath expression

numberValueOf

public Number numberValueOf(String xpathExpression)
numberValueOf evaluates an XPath expression and returns the numeric value of the XPath expression if the XPath expression results in a number, or null if the result is not a number.
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
the numeric result of the XPath expression or null if the result is not a number.

selectNodes

public List selectNodes(String xpathExpression)
selectNodes evaluates an XPath expression and returns the result as a List of Node instances or String instances depending on the XPath expression.
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
the list of Node or String instances depending on the XPath expression

selectNodes

public List selectNodes(String xpathExpression,
                        String comparisonXPathExpression)
selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
Parameters:
xpathExpression - is the XPath expression to be evaluated
comparisonXPathExpression - is the XPath expression used to compare the results by for sorting
Returns:
the list of Node instances sorted by the comparisonXPathExpression

selectNodes

public List selectNodes(String xpathExpression,
                        String comparisonXPathExpression,
                        boolean removeDuplicates)
selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
Parameters:
xpathExpression - is the XPath expression to be evaluated
comparisonXPathExpression - is the XPath expression used to compare the results by for sorting
removeDuplicates - if this parameter is true then duplicate values (using the comparisonXPathExpression) are removed from the result List.
Returns:
the list of Node instances sorted by the comparisonXPathExpression

selectObject

public Object selectObject(String xpathExpression)
selectObject evaluates an XPath expression and returns the result as an Object. The object returned can either be a List of one or more Nodeinstances or a scalar object like a Stringor a Numberinstance depending on the XPath expression.
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
the value of the XPath expression as a Listof Node instances, a Stringor a Numberinstance depending on the XPath expression.

selectSingleNode

public Node selectSingleNode(String xpathExpression)
selectSingleNode evaluates an XPath expression and returns the result as a single Node instance.
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
the Node matching the XPath expression

setDocument

public void setDocument(Document document)
setDocument sets the document of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.

This method should only be called from inside a Document implementation method and is not intended for general use.

Parameters:
document - is the new document of this node.

setName

public void setName(String name)
Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
Parameters:
name - is the new name of this node

setParent

public void setParent(Element parent)
setParent sets the parent relationship of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.

This method should only be called from inside an Element implementation method and is not intended for general use.

Parameters:
parent - is the new parent of this node.

setText

public void setText(String text)
Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
Parameters:
text - is the new textual value of this node

supportsParent

public boolean supportsParent()
supportsParent returns true if this node supports the parent relationship.

Some XML tree implementations are singly linked and only support downward navigation through children relationships. The default case is that both parent and children relationships are supported though for memory and performance reasons the parent relationship may not be supported.

Returns:
true if this node supports the parent relationship or false it is not supported

valueOf

public String valueOf(String xpathExpression)
valueOf evaluates an XPath expression and returns the textual representation of the results the XPath string-value of this node. The string-value for a given node type is defined in the XPath specification .
Parameters:
xpathExpression - is the XPath expression to be evaluated
Returns:
the string-value representation of the results of the XPath expression

write

public void write(Writer writer)
            throws IOException
write writes this node as the default XML notation for this node. If you wish to control the XML output (such as for pretty printing, changing the indentation policy etc.) then please use XMLWriter or its derivations.
Parameters:
writer - is the Writer to output the XML to

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