org.eclipse.rdf4j.model

## Interface Literal

- All Superinterfaces:
    Serializable, Value
  All Known Implementing Classes:
    AbstractLiteral, BooleanLiteral, BooleanLiteralImpl, BooleanMemLiteral, CalendarLiteral, CalendarMemLiteral, DecimalLiteral, DecimalMemLiteral, IntegerLiteral, IntegerMemLiteral, LiteralImpl, MemLiteral, NativeLiteral, NumericLiteral, NumericMemLiteral, SimpleLiteral

      public interface Literal
      extends Value

  An RDF-1.1 literal consisting of a label (the lexical value), a datatype, and optionally a language tag.

  Value accessor methods (for instance, `booleanValue()`) map literal lexical values conforming to the syntax of a supported XML Schema 1.1 datatype to a corresponding Java object.

  Author:
    Arjohn Kampman
  See Also:
    RDF-1.1 Concepts and Abstract Syntax, RDF 1.1 Concepts and Abstract Syntax - §5.1 The XML Schema Built-in Datatypes, XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes

- - ### Method Summary

    All Methods Instance Methods Abstract Methods Default Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `booleanValue()` Returns the `boolean` value of this literal.
    `byte` | `byteValue()` Returns the `byte` value of this literal.
    `XMLGregorianCalendar` | `calendarValue()` Returns the `XMLGregorianCalendar` value of this literal.
    `BigDecimal` | `decimalValue()` Returns the decimal value of this literal.
    `double` | `doubleValue()` Returns the `double` value of this literal.
    `boolean` | `equals(Object other)` Compares this literal to another object.
    `float` | `floatValue()` Returns the `float` value of this literal.
    `IRI` | `getDatatype()` Gets the datatype for this literal.
    `String` | `getLabel()` Gets the label (the lexical value) of this literal.
    `Optional<String>` | `getLanguage()` Gets the language tag for this literal, normalized to lower case.
    `int` | `hashCode()` Computes the hash code of this literal.
    `BigInteger` | `integerValue()` Returns the integer value of this literal.
    `int` | `intValue()` Returns the `int` value of this literal.
    `default boolean` | `isLiteral()` Check if the object is an instance of the given type.
    `long` | `longValue()` Returns the `long` value of this literal.
    `short` | `shortValue()` Returns the `short` value of this literal.
    `default java.time.temporal.TemporalAccessor` | `temporalAccessorValue()` Retrieves the `temporal accessor` value of this literal.
    `default java.time.temporal.TemporalAmount` | `temporalAmountValue()` Retrieves the `temporal amount` value of this literal.

    - ### Methods inherited from interface org.eclipse.rdf4j.model.Value

      `isBNode, isIRI, isResource, isTriple, stringValue`

- - ### Method Detail

    - #### isLiteral

          default boolean isLiteral()

      Description copied from interface: `Value`
      Check if the object is an instance of the given type. Typically 2x than using instanceof. For implementers: This default implementation is overridden in the repsective sub-interface.
      Specified by:
        `isLiteral` in interface `Value`
      Returns:
        true if instance of `Literal`

    - #### getLabel

          String getLabel()

      Gets the label (the lexical value) of this literal.
      Returns:
        The literal's label.

    - #### getLanguage

          Optional<String> getLanguage()

      Gets the language tag for this literal, normalized to lower case.
      Returns:
        The language tag for this literal, or `Optional.empty()` if it doesn't have one.

    - #### getDatatype

          IRI getDatatype()

      Gets the datatype for this literal.

      If `getLanguage()` returns a non-empty value than this must return `rdf:langString`. If no datatype was assigned to this literal by the creator, then this method must return `xsd:string`.

      Returns:
        The datatype for this literal.

    - #### booleanValue

          boolean booleanValue()

      Returns the `boolean` value of this literal.
      Returns:
        The `boolean` value of the literal.
      Throws:
        `IllegalArgumentException` - If the literal's label cannot be represented by a `boolean` .

    - #### byteValue

          byte byteValue()

      Returns the `byte` value of this literal.
      Returns:
        The `byte` value of the literal.
      Throws:
        `NumberFormatException` - If the literal cannot be represented by a `byte`.

    - #### shortValue

          short shortValue()

      Returns the `short` value of this literal.
      Returns:
        The `short` value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label cannot be represented by a `short`.

    - #### intValue

          int intValue()

      Returns the `int` value of this literal.
      Returns:
        The `int` value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label cannot be represented by a `int`.

    - #### longValue

          long longValue()

      Returns the `long` value of this literal.
      Returns:
        The `long` value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label cannot be represented by to a `long` .

    - #### integerValue

          BigInteger integerValue()

      Returns the integer value of this literal.
      Returns:
        The integer value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label is not a valid integer.

    - #### decimalValue

          BigDecimal decimalValue()

      Returns the decimal value of this literal.
      Returns:
        The decimal value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label is not a valid decimal.

    - #### floatValue

          float floatValue()

      Returns the `float` value of this literal.
      Returns:
        The `float` value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label cannot be represented by a `float`.

    - #### doubleValue

          double doubleValue()

      Returns the `double` value of this literal.
      Returns:
        The `double` value of the literal.
      Throws:
        `NumberFormatException` - If the literal's label cannot be represented by a `double`.

    - #### temporalAccessorValue

          default java.time.temporal.TemporalAccessor temporalAccessorValue()
                                                                     throws java.time.DateTimeException

      Retrieves the `temporal accessor` value of this literal.

      A temporal accessor representation can be given for literals whose label conforms to the syntax of the following XML Schema 1.1 date/time datatypes:

      - xsd:dateTime,
      - xsd:time,
      - xsd:date,
      - xsd:gYearMonth,
      - xsd:gYear,
      - xsd:gMonthDay,
      - xsd:gDay,
      - xsd:gMonth.

      Temporal accessor representations may be converted to specific `java.time` values like `OffsetDateTime` using target static factory methods, for instance `OffsetDateTime.from(literal.temporalAccessorValue())`.

      Note however that `java.time` doesn't include dedicated classes for some legal XML Schema date/time values, like offset dates (for instance, `2020-11-16+01:00`) and `xsd:gDay` (for instance, `---16`).

      Returns:
        the temporal accessor value of this literal
      Throws:
        `java.time.DateTimeException` - if this literal cannot be represented by a `TemporalAccessor` value
      Since:
        3.5.0
      See Also:
        The Java™ Tutorials – Trail: Date Time

    - #### temporalAmountValue

          default java.time.temporal.TemporalAmount temporalAmountValue()
                                                                 throws java.time.DateTimeException

      Retrieves the `temporal amount` value of this literal.

      A temporal amount representation can be given for literals whose label conforms to the syntax of the XML Schema 2 xsd:duration datatype.

      The adoption of the XML Schema 2 definition is a known deviation from the RDF 1.1 standard; well-formedness rules are relaxed to consider all duration components as optional and freely mixable.

      Temporal amount representations may be converted to specific `java.time` values like `Duration` using target static factory methods, for instance `Duration.from(literal.temporalAmountValue())`.

      Note however that `java.time` doesn't include dedicated classes for legal XML Schema duration values including both date and time components (for instance, `P1YT23H`).

      Returns:
        the temporal amount value of this literal
      Throws:
        `java.time.DateTimeException` - if this literal cannot be represented by a `TemporalAmount` value
      Since:
        3.5.0
      See Also:
        The Java™ Tutorials – Trail: Date Time

    - #### calendarValue

          XMLGregorianCalendar calendarValue()

      Returns the `XMLGregorianCalendar` value of this literal. A calendar representation can be given for literals whose label conforms to the syntax of the following XML Schema datatypes: `dateTime`, `time`, `date`, `gYearMonth`, `gMonthDay`, `gYear`, `gMonth` or `gDay`.
      Returns:
        The calendar value of the literal.
      Throws:
        `IllegalArgumentException` - If the literal cannot be represented by a `XMLGregorianCalendar`.

    - #### equals

          boolean equals(Object other)

      Compares this literal to another object.
      Overrides:
        `equals` in class `Object`
      Parameters:
        `other` - the object to compare this literal to
      Returns:
        `true`, if the other object is an instance of `Literal` and if their labels, language tags and datatypes are equal

    - #### hashCode

          int hashCode()

      Computes the hash code of this literal.
      Overrides:
        `hashCode` in class `Object`
      Returns:
        a hash code for this literal computed as `getLabel()``.hashCode()`

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