Module org.opengis.geoapi

Package org.opengis.feature

Interface AttributeType<V>

Type Parameters:

V - the type of attribute values. If the attribute supports multi-occurrences, then this is the type of elements (not the collection type).

All Superinterfaces:

IdentifiedType, PropertyType

All Known Subinterfaces:

DynamicAttributeType<V>

@Classifier(METACLASS)
@UML(identifier="AttributeType",
     specification=ISO_19109)
public interface AttributeType<V>
extends PropertyType

Definition of an attribute in a feature type. The name of attribute type is mandatory. The name scope is typically the name of the feature type containing this attribute, but this is not mandatory. The scope could also be defined by the ontology for example.

Note: compared to the Java language, AttributeType is equivalent to Field while FeatureType is equivalent to Class.

Value type

Attributes can be used for both spatial and non-spatial properties. Some examples are:

Attribute value type examples

Attribute name	Value type
Building shape	Geometry
Building owner	Responsibility
Horizontal accuracy	PositionalAccuracy

Attribute characterization

An Attribute can be characterized by other attributes. For example, an attribute that carries a measurement (e.g. air temperature) may have another attribute that holds the measurement accuracy (e.g. ±0.1°C). Such accuracy can be stored as a characteristic of the measurement attribute.

The characteristics() method in this AttributeType interface returns a description of all characteristics that attributes of this type may have. The actual characteristics values can be stored on a record-by-record basis in the Attribute.characteristics() map. However, in the common case of characteristics having a constant value for all records in a dataset, the constant can be given by the characteristic default value and Attribute.characteristics() may return an empty map (at implementation choice).

Since:

3.1

See Also:

• Attribute
• DynamicAttributeType

Method Summary

Modifier and Type	Method	Description
default Map<String,AttributeType<?>>	characteristics()	Other attribute types that describe this attribute type.
V	getDefaultValue()	Returns the default value for the attribute.
int	getMaximumOccurs()	Returns the maximum number of attribute values.
int	getMinimumOccurs()	Returns the minimum number of attribute values.
GenericName	getName()	Returns the name of this attribute type.
Class<V>	getValueClass()	Returns the type of attribute values.
Attribute<V>	newInstance()	Creates a new attribute instance of this type initialized to the default value.

Methods inherited from interface IdentifiedType

getDefinition, getDescription, getDesignation

Method Details

getName

@UML(identifier="name",
     obligation=MANDATORY,
     specification=ISO_19109)
GenericName getName()

Returns the name of this attribute type. For AttributeType, the name is mandatory.

Specified by:

getName in interface IdentifiedType

Returns:

the attribute type name.

getValueClass

@UML(identifier="valueType",
     obligation=MANDATORY,
     specification=ISO_19109)
Class<V> getValueClass()

Returns the type of attribute values.

Returns:

the type of attribute values.

getMinimumOccurs

@UML(identifier="cardinality",
     obligation=MANDATORY,
     specification=ISO_19109)
int getMinimumOccurs()

Returns the minimum number of attribute values. The returned value is greater than or equal to zero.

To be valid, an Attribute instance of this AttributeType shall have at least this minimum number of elements in its collection of values.

Returns:

the minimum number of attribute values.

getMaximumOccurs

@UML(identifier="cardinality",
     obligation=MANDATORY,
     specification=ISO_19109)
int getMaximumOccurs()

Returns the maximum number of attribute values. The returned value is greater than or equal to the getMinimumOccurs() value. If there is no maximum, then this method returns Integer.MAX_VALUE.

To be valid, an Attribute instance of this AttributeType shall have no more than this maximum number of elements in its collection of values.

Returns:

the maximum number of attribute values, or Integer.MAX_VALUE if none.

getDefaultValue

V getDefaultValue()

Returns the default value for the attribute. This value is used when an attribute is created and no value for it is specified.

Returns:

the default value for the attribute, or null if none.

characteristics

@UML(identifier="characterizeBy",
     obligation=OPTIONAL,
     specification=ISO_19109)
default Map<String,AttributeType<?>> characteristics()

Other attribute types that describe this attribute type. See "Attribute characterization" in class Javadoc for more information.

Example: an attribute that carries a measurement (e.g. air temperature) may have another attribute that holds the measurement accuracy.

The characteristics are enumerated in the map values. The map keys are the String representations of characteristics name, for more convenient lookups.

Returns:

other attribute types that describe this attribute type, or an empty map if none.

See Also:

• Attribute.characteristics()

newInstance

Attribute<V> newInstance()
                  throws UnsupportedOperationException

Creates a new attribute instance of this type initialized to the default value.

Returns:

a new attribute instance.

Throws:

UnsupportedOperationException - if this type does not support new instance creation.