Module org.apache.sis.metadata
Package org.apache.sis.metadata

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.

    • COMPACT

      public static final ValueExistencePolicy COMPACT
      Includes non-empty properties but omits title properties. Values associated to title properties are instead associated with the parent node. This policy is relevant for metadata classes annotated with Title­Property; for all other classes, this policy is identical 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 two policies:
      Comparison of "non-empty" and "compact" policy on the same metadata
      NON_EMPTY COMPACT 
       Citation
  ├─Title……………………… My document
  └─Date
     ├─Date………………… 2012/01/01
     └─Date type…… Creation
      		 
       Citation……………………… My document
  └─Date………………………… 2012/01/01
     └─Date type…… Creation
      This policy is the default behavior of Abstract­Metadata​.as­Tree­Table(), and consequently 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