Package ubic.gemma.persistence.util

Class IdentifiableUtils

java.lang.Object

ubic.gemma.persistence.util.IdentifiableUtils

public class IdentifiableUtils
extends Object

Utilities for Identifiable.

Author:

poirigui

Constructor Summary

Constructors

Constructor	Description
IdentifiableUtils()

Method Summary

Modifier and Type	Method	Description
static <T extends Identifiable> boolean	equals(@MayBeUninitialized T a, @MayBeUninitialized T b)	Compare two identifiables of the same type without risking initializing them.
static <T extends @MayBeUninitialized Identifiable> Map<Long,T>	getIdMap(Collection<T> entities)	Given a set of entities, create a map of their ids to the entities.
static <T extends @MayBeUninitialized Identifiable> List<Long>	getIds(Collection<T> entities)	Convert a collection of identifiable to their IDs.
static Long	getRequiredId(Identifiable identifiable)	Obtain the identifier of the object, throwing a NullPointerException if it is null.
static int	hash(@MayBeUninitialized Identifiable... identifiables)	Hash identifiables in a proxy-safe way using their IDs.
static <T, K extends @MayBeUninitialized Identifiable, U> Collector<T,?,Map<K,U>>	toIdentifiableMap(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper)	Collect results into an identifiable map.
static <T extends @MayBeUninitialized Identifiable> Collector<T,?,Set<T>>	toIdentifiableSet()	Collect results into an identifiable set.
static <T extends @MayBeUninitialized Identifiable> String	toString(T identifiable, Class<T> clazz)	Converts an identifiable to string, avoiding its initialization of it is a proxy.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

IdentifiableUtils

public IdentifiableUtils()

Method Details

getRequiredId

@Nonnull
public static Long getRequiredId(Identifiable identifiable)

Obtain the identifier of the object, throwing a NullPointerException if it is null.

Parameters:

identifiable - an entity to get the ID from

Throws:

NullPointerException - if the identifier is null

getIds

public static <T extends @MayBeUninitialized Identifiable>
List<Long> getIds(Collection<T> entities)

Convert a collection of identifiable to their IDs.

This function cannot be used on non-persistent entities (i.e. those with null IDs).

Parameters:

entities - entities

Returns:

returns a collection of IDs. Avoids using reflection by requiring that the given entities all implement the Identifiable interface.

getIdMap

public static <T extends @MayBeUninitialized Identifiable>
Map<Long,T> getIdMap(Collection<T> entities)

Given a set of entities, create a map of their ids to the entities.

Note: If more than one entity share the same ID, there is no guarantee on which will be kept in the final mapping. If the collection is ordered, the first encountered entity will be kept.

This function cannot be used on non-persistent entities (i.e. those with null IDs).

Type Parameters:

T - the type

Parameters:

entities - where id is called "id"

Returns:

the created map

toIdentifiableSet

public static <T extends @MayBeUninitialized Identifiable>
Collector<T,?,Set<T>> toIdentifiableSet()

Collect results into an identifiable set.

This uses Identifiable.getId() for comparing elements, making the collection safe for holding proxies unlike a HashSet that relies on Object.hashCode().

This collector cannot be used with non-persistent entities (i.e. those with null IDs).

See Also:

• Collectors.toSet()

toIdentifiableMap

public static <T,
K extends @MayBeUninitialized Identifiable,
U>
Collector<T,?,Map<K,U>> toIdentifiableMap(Function<? super T,? extends K> keyMapper,
 Function<? super T,? extends U> valueMapper)

Collect results into an identifiable map.

This uses Identifiable.getId() for comparing elements, making the collection safe for holding proxies unlike a HashMap that relies on Object.hashCode().

This collector cannot be used with non-persistent entities (i.e. those with null IDs).

See Also:

• Collectors.toMap(java.util.function.Function<? super T, ? extends K>, java.util.function.Function<? super T, ? extends U>)

toString

public static <T extends @MayBeUninitialized Identifiable>
String toString(T identifiable,
 Class<T> clazz)

Converts an identifiable to string, avoiding its initialization of it is a proxy.

hash

public static int hash(@MayBeUninitialized Identifiable... identifiables)

Hash identifiables in a proxy-safe way using their IDs.

Hashing an entity that does ont have an assigned ID is not allowed as its hash code would change once persisted.

equals

public static <T extends Identifiable> boolean equals(@Nullable
 @MayBeUninitialized T a,
 @Nullable
 @MayBeUninitialized T b)

Compare two identifiables of the same type without risking initializing them.

Returns:

true if they have the same ID or are equal according to Objects.equals(Object, Object).