Enum Class ValueExistencePolicy

Object
Enum<ValueExistencePolicy>
ValueExistencePolicy
All Implemented Interfaces:
Serializable, Comparable<Value­Existence­Policy>, Constable
public enum ValueExistencePolicy extends Enum<ValueExistencePolicy>
Whatever Metadata­Standard​.as­Value­Map(…) shall contain entries for null, nil or empty values. By default the value map does not provide entries for null metadata properties, nil objects or empty collections. This enumeration allows to control this behavior.

Difference between null and nil

A null property is a reference which is null in the Java sense. Null references can be used for missing properties when no information is provided about why the property is missing. On the other hand, a nil object is a placeholder for a missing property similar in purpose to null references, except that an explanation about why the property is missing can be attached to those objects. Those explanations can be obtained by calls to the Nil­Reason​.for­Object(Object) method.
Since:
0.3
See Also:

  • Enum Constant Details

    • ALL

      public static final ValueExistencePolicy ALL
      Includes all entries in the map, including those having a null value or an empty collection.

    • NON_NULL

      public static final ValueExistencePolicy NON_NULL
      Includes only the non-null properties. Nil­Objects are included. Collections are included no matter if they are empty or not.

      The set of NON_NULL properties is a subset of ALL properties.

    • NON_NIL

      public static final ValueExistencePolicy NON_NIL
      Includes only the non-null and non-nil properties. Collections are included no matter if they are empty or not.

      The set of NON_NIL properties is a subset of NON_NULL properties.

      Since:
      0.4

    • NON_EMPTY

      public static final ValueExistencePolicy NON_EMPTY
      Includes only the properties that are non-null, non-nil and non empty. A non-null and non-nil property is considered empty in any of the following cases: This is the default behavior of Abstract­Metadata​.as­Map().

      The set of NON_EMPTY properties is a subset of NON_NIL properties.

    • TITLED

      public static final ValueExistencePolicy TITLED
      Same as NON_EMPTY, but with the addition of titles associated with metadata objects. Metadata objects such as
      invalid reference 
      Citation
      are normally associated with no textual value. Texts are rather associated with properties of the metadata object. But some metadata classes have a property which can summarize the whole object. For example, for Citation objects, this property is the citation title.

      The property to use as the title of a metadata object is specified by the Title­Property annotation on the metadata implementation class (for example, Default­Citation). When using this TITLED or the COMPACT policy, the values of the properties identified by the Title­Property annotations are copied in the root of the metadata sub-tree. See COMPACT Javadoc for an example.

      Since:
      1.7
      See Also:

    • COMPACT

      public static final ValueExistencePolicy COMPACT
      Same as TITLED but omitting the properties which have been used as titles. This omission removes a redundancy, thus making the tree a little bit more compact, at the expanse of a slight departure from the metadata model. For metadata classes without Title­Property annotation, this policy is equivalent to NON_EMPTY.

      Example

      The Default­Citation and Default­Citation­Date classes are annotated with @Title­Property(name="title") and @Title­Property(name="date") respectively. The following table compares the trees produced by three policies:
      Comparison of policies on the same metadata
      NON_EMPTY TITLED COMPACT 
      Citation
 ├─Title……………………… My document
 └─Date
    ├─Date………………… 2012/01/01
    └─Date type…… Creation
      		 
      Citation……………………… My document
 ├─Title……………………… My document
 └─Date………………………… 2012/01/01
    ├─Date………………… 2012/01/01
    └─Date type…… Creation
      		 
      Citation……………………… My document
 └─Date………………………… 2012/01/01
    └─Date type…… Creation
      This COMPACT policy is the default behavior of Abstract­Metadata​.as­Tree­Table(). Therefore, this policy defines the default rendering of Abstract­Metadata​.to­String().
      Since:
      0.8
      See Also:

  • Method Details

    • values

      public static ValueExistencePolicy[] values()
      Returns an array containing the constants of this enum class, in the order they are declared.
      Returns:
      an array containing the constants of this enum class, in the order they are declared

    • valueOf

      public static ValueExistencePolicy valueOf(String name)
      Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)
      Parameters:
      name - the name of the enum constant to be returned.
      Returns:
      the enum constant with the specified name
      Throws:
      Illegal­Argument­Exception - if this enum class has no constant with the specified name
      Null­Pointer­Exception - if the argument is null