Interface Literal
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- All Superinterfaces:
FrontsNode
,RDFNode
- All Known Implementing Classes:
LiteralImpl
public interface Literal extends RDFNode
An RDF Literal.In RDF2003 literals can be typed. If typed then the literal comprises a datatype, a lexical form and a value (together with an optional xml:lang string). Old style literals have no type and are termed "plain" literals.
Implementations of this interface should be able to support both plain and typed literals. In the case of typed literals the primitive accessor methods such as getInt() determine if the literal value can be coerced to an appropriate java wrapper class. If so then the class is unwrapped to extract the primitive value returned. If the coercion fails then a runtime DatatypeFormatException is thrown.
In the case of plain literals then the primitive accessor methods duplicate the behaviour of jena1. The literal is internally stored in lexical form but the accessor methods such as getInt will attempt to parse the lexical form and if successful will return the primitive value.
Object (i.e. non-primitive) values are supported. In the case of typed literals then a global TypeMapper registry determines what datatype representation to use for a given Object type. In the case of plain literals then the object will be stored in the lexical form given by its
toString
method. Factory objects, provided by the application, are needed in that case to covert the lexical form back into the appropriate object type.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description boolean
equals(java.lang.Object o)
Test whether another object is equal to this object.boolean
getBoolean()
If the literal is interpretable as a Boolean return its value as a boolean.byte
getByte()
If the literal is interpretable as a Byte return its value.char
getChar()
If the literal is interpretable as a Char return its value.RDFDatatype
getDatatype()
Return the datatype of the literal.java.lang.String
getDatatypeURI()
Return the uri of the datatype of the literal.double
getDouble()
If the literal is interpretable as a Double return its value.float
getFloat()
If the literal is interpretable as a Float return its value.int
getInt()
If the literal is interpretable as a Integer return its value.java.lang.String
getLanguage()
If a language is defined for this literal return itjava.lang.String
getLexicalForm()
Return the lexical form of the literal.long
getLong()
If the literal is interpretable as a Long return its value.short
getShort()
If the literal is interpretable as a Short return its value.java.lang.String
getString()
If the literal is interpretable as a string return its value.java.lang.Object
getValue()
Return the value of the literal.Literal
inModel(Model m)
Answer a version of this literal in the model m.boolean
isWellFormedXML()
Answer true iff this literal is (or claims to be) well-formed XML.boolean
sameValueAs(Literal other)
Test that two literals are semantically equivalent.-
Methods inherited from interface org.apache.jena.graph.FrontsNode
asNode
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Methods inherited from interface org.apache.jena.rdf.model.RDFNode
as, asLiteral, asResource, canAs, getModel, isAnon, isLiteral, isResource, isStmtResource, isURIResource, toString, visitWith
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Method Detail
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inModel
Literal inModel(Model m)
Answer a version of this literal in the model m. If this literal is already in m, answer itself rather than create a new literal. This method covariantly overrides the method in RDFNode.
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getValue
java.lang.Object getValue()
Return the value of the literal. In the case of plain literals this will return the literal string. In the case of typed literals it will return a java object representing the value. In the case of typed literals representing a java primitive then the appropriate java wrapper class (Integer etc) will be returned. A Long value may be converted to its equivalent Integer value if there is no loss of precision (i.e. if the value is within the Integer minimum and maximum values).
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getDatatype
RDFDatatype getDatatype()
Return the datatype of the literal.
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getDatatypeURI
java.lang.String getDatatypeURI()
Return the uri of the datatype of the literal.
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getLexicalForm
java.lang.String getLexicalForm()
Return the lexical form of the literal.
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getBoolean
boolean getBoolean()
If the literal is interpretable as a Boolean return its value as a boolean. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a boolean
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getByte
byte getByte()
If the literal is interpretable as a Byte return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a byte
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getShort
short getShort()
If the literal is interpretable as a Short return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a short
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getInt
int getInt()
If the literal is interpretable as a Integer return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as an int
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getLong
long getLong()
If the literal is interpretable as a Long return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a long
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getChar
char getChar()
If the literal is interpretable as a Char return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a char
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getFloat
float getFloat()
If the literal is interpretable as a Float return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a float
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getDouble
double getDouble()
If the literal is interpretable as a Double return its value. Plain literals are interpreted by parsing their lexical representation, typed literals are interpreted by coercion of the java object representing their value.- Returns:
- the literal interpeted as a double
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getString
java.lang.String getString()
If the literal is interpretable as a string return its value. For typed literals this will throw an error for non string literals and one needs to use getLexicalForm to return the string form of other datatypes.- Returns:
- the literal string
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getLanguage
java.lang.String getLanguage()
If a language is defined for this literal return it- Returns:
- the language for this literal if it exists, or empty string if none
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isWellFormedXML
boolean isWellFormedXML()
Answer true iff this literal is (or claims to be) well-formed XML.
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equals
boolean equals(java.lang.Object o)
Test whether another object is equal to this object.A plain Literal is equal to another object only if the object is also a plain Literal and the string value and language of both literals are equal. In the case of a typed literal equality is defined by the datatype equality function on the value spaces and may or may not include comparison of the lang strings.
- Overrides:
equals
in classjava.lang.Object
- Parameters:
o
- The object to test against- Returns:
- true if the the objects are equal, false otherwise
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sameValueAs
boolean sameValueAs(Literal other)
Test that two literals are semantically equivalent. In some cases this may be the sames as equals, in others equals is stricter. For example, two xsd:int literals with the same value but different language tag are semantically equivalent but distinguished by the java equality function in order to support round tripping.
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