Package org.apache.sis.metadata

Enum ValueExistencePolicy

Object

Enum<ValueExistencePolicy>

ValueExistencePolicy

All Implemented Interfaces:

Serializable, Comparable<Value­Existence­Policy>

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:

Metadata­Standard.as­Value­Map(Object, Class, Key­Name­Policy, Value­Existence­Policy)

Defined in the sis-metadata module

Enum Constant Summary

Enum Constants

Enum Constant	Description
ALL	Includes all entries in the map, including those having a null value or an empty collection.
COMPACT	Includes non-empty properties but omits title properties.
NON_EMPTY	Includes only the properties that are non-null, non-nil and non empty.
NON_NIL	Includes only the non-null and non-nil properties.
NON_NULL	Includes only the non-null properties.

Method Summary

Modifier and Type	Method	Description
static ValueExistencePolicy	valueOf(String name)	Returns the enum constant of this type with the specified name.
static ValueExistencePolicy[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class Enum

clone, compare­To, equals, finalize, get­Declaring­Class, hash­Code, name, ordinal, to­String, value­Of

Methods inherited from class Object

get­Class, notify, notify­All, wait, wait, wait

Enum Constant Detail

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:

• It is a character sequence containing only whitespaces.
• It is an empty collection.
• It is an empty map.
• It is an empty array (of length 0).

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:

Title­Property

Method Detail

values

public static ValueExistencePolicy[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (ValueExistencePolicy c : ValueExistencePolicy.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static ValueExistencePolicy valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (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 type has no constant with the specified name

Null­Pointer­Exception - if the argument is null