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 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 provide a representation in
which entity references are not expanded. These child nodes may be either
Text or EntityReference nodes. Because the DOM
Core is not aware of attribute types, it treats all attribute values as
simple strings, even if the DTD or schema declares them as having
tokenized types.
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.
getValue
public java.lang.String getValue()
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 setAttribute on the Element
interface.
Throws:
DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
setValue
public void setValue(java.lang.String value)
throws DOMException