org.jrdf.graph
Class AbstractLiteral

java.lang.Object
  org.jrdf.graph.AbstractLiteral

All Implemented Interfaces:

Serializable, Literal, Node, ObjectNode, TypedNodeVisitable, Value

Direct Known Subclasses:

LiteralImpl, LiteralImpl

public abstract class AbstractLiteral
extends Object
implements Literal, Serializable

A base implementation of an RDF Literal.

Version:

$Revision: 1822 $

Author:

Andrew Newman, Simon Raboczi

See Also:

Serialized Form

Field Summary

protected URI	datatypeURI RDF datatype URI, NullURI for untyped literal.
protected String	language The language code of the literal.
protected DatatypeValue	value The lexical form of the literal.

Constructor Summary

protected	AbstractLiteral()
protected	AbstractLiteral(Object newObject) Construct a datatype literal based on an existing Java class.
protected	AbstractLiteral(String newLexicalForm) Construct a plain literal.
protected	AbstractLiteral(String newLexicalForm, String newLanguage) Construct a literal with language.
protected	AbstractLiteral(String newLexicalForm, URI newDatatypeURI) Construct a datatyped literal.

Method Summary

void	accept(TypedNodeVisitor visitor) Accept a call from a TypedNodeVisitor.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
URI	getDatatypeURI() Returns the URI of the RDF datatype of this resource, or NO_DATATYPE for a plain literal.
DatatypeValue	getDatatypeValue() Obtain the data type representation of this literal.
String	getEscapedForm() Provide a legible representation of a literal, following the N-Triples format defined in §3.2 of the W3C's RDF Test Cases Recommendation.
String	getEscapedLexicalForm() Returns an escaped lexical form where double quotes and backslashes are escaped.
String	getLanguage() Returns the language code of the literal, or "" if no language specified.
String	getLexicalForm() Obtain the text of this literal.
Object	getValue() Obtain a Java native representation of the datatype.
int	hashCode() Returns a hash-code value for this literal.
boolean	isDatatypedLiteral() Returns true if the literal is a datatype literal.
boolean	isLanguageLiteral() Returns true if the literal is a language literal.
boolean	isPlainLiteral() Returns true if the literal is a untyped/plain literal.
boolean	isWellFormedXML() Whether the literal is well formed XML.
String	toString() Returns the lexical form.

Methods inherited from class java.lang.Object

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

Field Detail

value

protected DatatypeValue value

The lexical form of the literal.

language

protected String language

The language code of the literal.

datatypeURI

protected URI datatypeURI

RDF datatype URI, NullURI for untyped literal.

Constructor Detail

AbstractLiteral

protected AbstractLiteral()

AbstractLiteral

protected AbstractLiteral(String newLexicalForm)

Construct a plain literal.

Parameters:

newLexicalForm - the text part of the literal

Throws:

IllegalArgumentException - if newLexicalForm is null

AbstractLiteral

protected AbstractLiteral(String newLexicalForm,
                          String newLanguage)

Construct a literal with language.

Parameters:

newLexicalForm - the text part of the literal

newLanguage - the language code, possibly the empty string but not null

Throws:

IllegalArgumentException - if lexicalForm or lang are null

AbstractLiteral

protected AbstractLiteral(String newLexicalForm,
                          URI newDatatypeURI)

Construct a datatyped literal.

Parameters:

newLexicalForm - the text part of the literal

newDatatypeURI - the URI for a datatyped literal

Throws:

IllegalArgumentException - if lexicalForm or datatype are null

AbstractLiteral

protected AbstractLiteral(Object newObject)

Construct a datatype literal based on an existing Java class.

Parameters:

newObject - the object to use to construct the literal from. Uses a map of registered classes to creator objects.

Throws:

IllegalArgumentException - if the class is not registered to convert to a datatype.

Method Detail

getLexicalForm

public String getLexicalForm()

Description copied from interface: Value

Obtain the text of this literal.

Specified by:

getLexicalForm in interface Value

Returns:

the text of the literal, never null

getValue

public Object getValue()

Description copied from interface: Literal

Obtain a Java native representation of the datatype.

Specified by:

getValue in interface Literal

Specified by:

getValue in interface Value

Returns:

a Java native representation of the datatype.

getDatatypeValue

public DatatypeValue getDatatypeValue()

Description copied from interface: Literal

Obtain the data type representation of this literal.

Specified by:

getDatatypeValue in interface Literal

Returns:

the value object (data type) of this literal.

getLanguage

public String getLanguage()

Description copied from interface: Literal

Returns the language code of the literal, or "" if no language specified.

Specified by:

getLanguage in interface Literal

Returns:

the language code of the literal, or "" if no language specified.

isDatatypedLiteral

public boolean isDatatypedLiteral()

Description copied from interface: Literal

Returns true if the literal is a datatype literal.

Specified by:

isDatatypedLiteral in interface Literal

Returns:

true if the literal is a datatype literal.

isLanguageLiteral

public boolean isLanguageLiteral()

Description copied from interface: Literal

Returns true if the literal is a language literal.

Specified by:

isLanguageLiteral in interface Literal

Returns:

true if the literal is a language literal.

isPlainLiteral

public boolean isPlainLiteral()

Description copied from interface: Literal

Returns true if the literal is a untyped/plain literal.

Specified by:

isPlainLiteral in interface Literal

Returns:

true if the literal is a untyped/plain literal.

isWellFormedXML

public boolean isWellFormedXML()

Whether the literal is well formed XML.

Specified by:

isWellFormedXML in interface Value

Returns:

whether the literal is well formed XML.

getDatatypeURI

public URI getDatatypeURI()

Returns the URI of the RDF datatype of this resource, or NO_DATATYPE for a plain literal.

Specified by:

getDatatypeURI in interface Literal

Returns:

the URI of the RDF datatype of this resource, or NO_DATATYPE for a plain literal.

accept

public void accept(TypedNodeVisitor visitor)

Accept a call from a TypedNodeVisitor.

Specified by:

accept in interface TypedNodeVisitable

Parameters:

visitor - the object doing the visiting.

hashCode

public int hashCode()

Description copied from interface: Literal

Returns a hash-code value for this literal. The hash code is based upon XORing all of the literal's components hash codes including the lexical form, datatype, and language.

Specified by:

hashCode in interface Literal

Overrides:

hashCode in class Object

Returns:

a hash-code value for this literal.

equals

public boolean equals(Object obj)

Description copied from interface: Literal

Indicates whether some other object is "equal to" this one.

A literal is equal to another literal if:

• The strings of the two lexical forms compare equal, character by character.
• Either both or neither have language tags.
• The language tags, if any, compare equal.
• Either both or neither have datatype URIs.
• The two datatype URIs, if any, compare equal, character by character.

Specified by:

equals in interface Literal

Overrides:

equals in class Object

Parameters:

obj - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

getEscapedForm

public String getEscapedForm()

Provide a legible representation of a literal, following the N-Triples format defined in §3.2 of the W3C's RDF Test Cases Recommendation.

Well-formed Unicode surrogate pairs in the lexical form are escaped as a single 8-digit hexadecimal \U escape sequence rather than a pair of 4-digit &x5C;u sequences representing the surrogates.

Specified by:

getEscapedForm in interface Literal

Returns:

this instance in N-Triples format

toString

public String toString()

Returns the lexical form.

Specified by:

toString in interface Literal

Overrides:

toString in class Object

Returns:

the lexical form.

getEscapedLexicalForm

public String getEscapedLexicalForm()

Description copied from interface: Literal

Returns an escaped lexical form where double quotes and backslashes are escaped.

Specified by:

getEscapedLexicalForm in interface Literal

Returns:

String the lexical form.