org.lenskit.data.entities

Interface Entity

All Known Implementing Classes:

AbstractEntity, Rating

@Immutable
 @BuiltBy(value=BasicEntityBuilder.class)
public interface Entity

Base class for data entities in LensKit. The LensKit data model consists of various entities, each of which has a type, a numeric identifier (as a long), and additional data (attributes) in a key-value mapping.

Two entities are equal if their types, IDs, and data are equal.

Identifiers are scoped per-type; it is acceptable to LensKit for two entities with different types to have the same identifier, and they are not considered to be the same entity.

Attributes are identified by name; for type safety, the are often accessed using typed names, such as those defined in CommonAttributes. Attribute values cannot be null; if you must safely handle the absence of an attribute, test with hasAttribute(TypedName) or use maybeGet(TypedName).

Method Summary

Modifier and Type	Method and Description
Map<String,Object>	asMap() View this entity as a map.
Object	get(String attr) Get the value of an attribute by name.
<T> T	get(TypedName<T> name) Get the value of an attribute.
Set<String>	getAttributeNames() Get the names of the attributes in this entity.
Collection<Attribute<?>>	getAttributes() Get the attribute-value pairs.
boolean	getBoolean(TypedName<Boolean> name) Get the value of a attr that contains a boolean.
double	getDouble(TypedName<Double> name) Get the value of a attr that contains a double.
long	getId() Get the identifier of this entity.
int	getInteger(TypedName<Integer> name) Get the value of a attr that contains a int.
long	getLong(TypedName<Long> name) Get the value of a attribute that contains a long.
EntityType	getType() Get the type of this entity.
Set<TypedName<?>>	getTypedAttributeNames() Get the attributes in this entity.
boolean	hasAttribute(String name) Check if the entity has a field with a particular name.
boolean	hasAttribute(TypedName<?> name) Check if the entity has a attribute.
Object	maybeGet(String attr) Get the value of a possibly-missing attribute by name.
<T> T	maybeGet(TypedName<T> name) Get the value of a possibly-missing attribute.

Method Detail

getId

long getId()

Get the identifier of this entity.

Returns:

The entity identifier.

getType

EntityType getType()

Get the type of this entity.

Returns:

The entity’s type.

getAttributeNames

Set<String> getAttributeNames()

Get the names of the attributes in this entity.

getTypedAttributeNames

Set<TypedName<?>> getTypedAttributeNames()

Get the attributes in this entity.

getAttributes

Collection<Attribute<?>> getAttributes()

Get the attribute-value pairs.

asMap

Map<String,Object> asMap()

View this entity as a map.

Returns:

A map reflecting the entity’s data.

hasAttribute

boolean hasAttribute(String name)

Check if the entity has a field with a particular name.

Parameters:

name - The field name to look for.

Returns:

true if the entity has a field named name.

hasAttribute

boolean hasAttribute(TypedName<?> name)

Check if the entity has a attribute.

Parameters:

name - The attribute name to look for.

Returns:

true if the entity contains attribute and the value is of the associated type. that the data is of a compatible type.

get

@Nonnull
<T> T get(TypedName<T> name)

Get the value of an attribute.

Parameters:

name - The attribute name.

T - The attribute’s type.

Returns:

The attribute’s value.

Throws:

NoSuchAttributeException - if the specified attribute is not present.

IllegalArgumentException - if a attribute with the same name as attribute is present, but it is of an incompatible type.

get

@Nonnull
Object get(String attr)

Get the value of an attribute by name.

Parameters:

attr - The attribute name.

Returns:

The attribute value.

Throws:

NoSuchAttributeException - if the specified attribute is not present.

maybeGet

@Nullable
<T> T maybeGet(TypedName<T> name)

Get the value of a possibly-missing attribute.

Parameters:

name - The attribute name.

T - The attribute’s type.

Returns:

The attribute’s value, or null if it is not present.

Throws:

IllegalArgumentException - if a attribute with the same name as attribute is present, but it is of an incompatible type.

maybeGet

@Nullable
Object maybeGet(String attr)

Get the value of a possibly-missing attribute by name.

Parameters:

attr - The attribute name.

Returns:

The attribute’s value, or null if it is not present.

getLong

long getLong(TypedName<Long> name)

Get the value of a attribute that contains a long.

Parameters:

name - The attribute name.

Returns:

The attribute’s value.

Throws:

NoSuchAttributeException - if the specified attribute is not present.

IllegalArgumentException - if the attribute is present but its type is not Long.

getDouble

double getDouble(TypedName<Double> name)

Get the value of a attr that contains a double.

Parameters:

name - The attribute name.

Returns:

The attribute’s value.

Throws:

NoSuchAttributeException - if the specified attr is not present.

IllegalArgumentException - if the attr is present but is not of type Double.

getInteger

int getInteger(TypedName<Integer> name)

Get the value of a attr that contains a int.

Parameters:

name - The attribute name.

Returns:

The attribute’s value.

Throws:

NoSuchAttributeException - if the specified attr is not present.

IllegalArgumentException - if the attr is present but is not of type Integer.

getBoolean

boolean getBoolean(TypedName<Boolean> name)

Get the value of a attr that contains a boolean.

Parameters:

name - The attribute name.

Returns:

The attribute’s value.

Throws:

NoSuchAttributeException - if the specified attr is not present.

IllegalArgumentException - if the attr is present but is not of type Boolean.