org.w3c.dom
Interface Attr

All Superinterfaces:

Node

public interface Attr

extends Node

The Attr interface represents an attribute in an Element object. Typically the allowable values for the attribute are defined in a document type definition.

Attr objects inherit the Node interface, but since they are not actually child nodes of the element they describe, the DOM does not consider them part of the document tree. Thus, the Node attributes parentNode, previousSibling, and nextSibling have a null value for Attr objects. The DOM takes the view that attributes are properties of elements rather than having a separate identity from the elements they are associated with; this should make it more efficient to implement such features as default attributes associated with all elements of a given type. Furthermore, Attr nodes may not be immediate children of a DocumentFragment. However, they can be associated with Element nodes contained within a DocumentFragment. In short, users and implementors of the DOM need to be aware that Attr nodes have some things in common with other objects inheriting the Node interface, but they also are quite distinct.

The attribute's effective value is determined as follows: if this attribute has been explicitly assigned any value, that value is the attribute's effective value; otherwise, if there is a declaration for this attribute, and that declaration includes a default value, then that default value is the attribute's effective value; otherwise, the attribute does not exist on this element in the structure model until it has been explicitly added. Note that the Node.nodeValue attribute on the Attr instance can also be used to retrieve the string version of the attribute's value(s).

In XML, where the value of an attribute can contain entity references, the child nodes of the Attr node may be either Text or EntityReference nodes (when these are in use; see the description of EntityReference for discussion).

The DOM Core represents all attribute values as simple strings, even if the DTD or schema associated with the document declares them of some specific type such as tokenized.

See also the Document Object Model (DOM) Level 2 Core Specification and the Document Object Model (DOM) Level 3 Core Specification.

Field Summary

Fields inherited from interface org.w3c.dom.Node

ATTRIBUTE_NODE, CDATA_SECTION_NODE, COMMENT_NODE, DOCUMENT_FRAGMENT_NODE, DOCUMENT_NODE, DOCUMENT_TYPE_NODE, ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, NOTATION_NODE, PROCESSING_INSTRUCTION_NODE, TEXT_NODE

Method Summary

String	getName() Returns the name of this attribute.
Element	getOwnerElement() The Element node this attribute is attached to or null if this attribute is not in use.
boolean	getSpecified() If this attribute was explicitly given a value in the original document, this is true; otherwise, it is false.
String	getValue() Returns the value of this attribute.
boolean	isId() Returns whether this attribute is known to be of type ID or not.
void	setValue(String value) Sets the value of this attribute.

Methods inherited from interface org.w3c.dom.Node

appendChild, cloneNode, getAttributes, getChildNodes, getFeature, getFirstChild, getLastChild, getLocalName, getNamespaceURI, getNextSibling, getNodeName, getNodeType, getNodeValue, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getTextContent, getUserData, hasAttributes, hasChildNodes, insertBefore, isSupported, normalize, removeChild, replaceChild, setNodeValue, setPrefix, setTextContent, setUserData

Method Detail

getName

public String getName()

Returns the name of this attribute. If Node.localName is different from null, this attribute is a qualified name.

Returns:

the attribute name

getSpecified

public boolean getSpecified()

If this attribute was explicitly given a value in the original document, this is true; otherwise, it is false. Note that the implementation is in charge of this attribute, not the user. If the user changes the value of the attribute (even if it ends up having the same value as the default value) then the specified flag is automatically flipped to true. To re-specify the attribute as the default value from the DTD, the user must delete the attribute. The implementation will then make a new attribute available with specified set to false and the default value (if one exists).
In summary: If the attribute has an assigned value in the document then specified is true, and the value is the assigned value. If the attribute has no assigned value in the document and has a default value in the DTD, then specified is false, and the value is the default value in the DTD. If the attribute has no assigned value in the document and has a value of #IMPLIED in the DTD, then the attribute does not appear in the structure model of the document. If the ownerElement attribute is null (i.e. because it was just created or was set to null by the various removal and cloning operations) specified is true.

Returns:

true if this attribute was explicitly specified, otherwise false

getValue

public String getValue()

Returns the value of this attribute. On retrieval, the value of the attribute is returned as a string. Character and general entity references are replaced with their values. See also the method getAttribute on the Element interface.
On setting, this creates a Text node with the unparsed contents of the string. I.e. any characters that an XML processor would recognize as markup are instead treated as literal text. See also the method Element.setAttribute.
Some specialized implementations, such as some [SVG 1.1] implementations, may do normalization automatically, even after mutation; in such case, the value on retrieval may differ from the value on setting.

Returns:

a String containing the value of this attribute

setValue

public void setValue(String value)
              throws DOMException

Sets the value of this attribute. On setting, this creates a Text node with the unparsed contents of the string. I.e. any characters that an XML processor would recognize as markup are instead treated as literal text. See also the method Element.setAttribute.
Some specialized implementations, such as some [SVG 1.1] implementations, may do normalization automatically, even after mutation; in such case, the value on retrieval may differ from the value on setting.

Parameters:

value - a String containing the value of this attribute

Throws:

DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.

getOwnerElement

public Element getOwnerElement()

The Element node this attribute is attached to or null if this attribute is not in use.

Returns:

the Element node this attribute is attached to, or null

Since:

DOM Level 2

isId

public boolean isId()

Returns whether this attribute is known to be of type ID or not. In other words, whether this attribute contains an identifier for its owner element or not. When it is and its value is unique, the ownerElement of this attribute can be retrieved using the method Document.getElementById.

Note: The JSR 280 DOM subset does not support XML schema or Document.normalizeDocument(), and thus supports only a subset of the DOM 3 mechanisms for identifying ID attributes:

• the use of the methods Element.setIdAttribute(), Element.setIdAttributeNS(), or Element.setIdAttributeNode(), i.e. it is an user-determined ID attribute.

Returns:

true if the attribute is of type ID, otherwise false

Since:

DOM Level 3