= ServiceRegistry
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Collects together methods for injecting or looking up domain services (either provided by the framework or application-specific) currently known to the runtime.

== API

[source,java]
.ServiceRegistry.java
----
interface ServiceRegistry {
  Can<T> select(Class<T> type, Annotation[] qualifiers)     // <.>
  Can<T> select(Class<T> type)     // <.>
  Stream<_SingletonBeanProvider> streamRegisteredBeansOfType(Class<?> requiredType)     // <.>
  Stream<_SingletonBeanProvider> streamRegisteredBeans()     // <.>
  Optional<_SingletonBeanProvider> lookupRegisteredBeanById(LogicalType id)     // <.>
  _SingletonBeanProvider lookupRegisteredBeanByIdElseFail(LogicalType id)     // <.>
  Optional<?> lookupBeanById(String id)
  Optional<T> lookupService(Class<T> serviceClass)     // <.>
  Optional<T> lookupService(Class<T> serviceClass, Comparator<Object> comparator)     // <.>
  T lookupServiceElseFail(Class<T> serviceClass)     // <.>
  void clearRegisteredBeans()     // <.>
}
----

<.> xref:#select_Class_Annotation[select(Class, Annotation)]
+
--
Obtains a xref:refguide:commons:index/collections/Can.adoc[Can] container containing any matching instances for the given required type and additional required qualifiers.
--
<.> xref:#select_Class[select(Class)]
+
--
Obtains a xref:refguide:commons:index/collections/Can.adoc[Can] container containing any matching instances for the given required type.
--
<.> xref:#streamRegisteredBeansOfType_Class[streamRegisteredBeansOfType(Class)]
+
--
Streams all registered bean adapters implementing the requested type.
--
<.> xref:#streamRegisteredBeans_[streamRegisteredBeans()]
+
--
Returns all bean adapters that have been registered.
--
<.> xref:#lookupRegisteredBeanById_LogicalType[lookupRegisteredBeanById(LogicalType)]
+
--
Returns a registered bean of given _name_ .
--
<.> xref:#lookupRegisteredBeanByIdElseFail_LogicalType[lookupRegisteredBeanByIdElseFail(LogicalType)]
+
--
Returns a registered bean of given _name_ , or throws when no such bean.
--
<.> xref:#lookupService_Class[lookupService(Class)]
+
--
Returns a domain service implementing the requested type.
--
<.> xref:#lookupService_Class_Comparator[lookupService(Class, Comparator)]
+
--
Returns a domain service implementing the requested type.
--
<.> xref:#lookupServiceElseFail_Class[lookupServiceElseFail(Class)]
+
--
Looks up a domain service of the requested type (same as _#lookupService(Class)_ ) but throws a _NoSuchElementException_ if there are no such instances.
--
<.> xref:#clearRegisteredBeans_[clearRegisteredBeans()]
+
--
Invalidates any cached service adapters that might hold a reference to the current _org.apache.causeway.core.metamodel.specloader.SpecificationLoader_ . Particularly useful when discarding a meta-model instance, that is, purging the _org.apache.causeway.core.metamodel.spec.ObjectSpecification_ cache.
--

== Members

[#select_Class_Annotation]
=== select(Class, Annotation)

Obtains a xref:refguide:commons:index/collections/Can.adoc[Can] container containing any matching instances for the given required type and additional required qualifiers.

[#select_Class]
=== select(Class)

Obtains a xref:refguide:commons:index/collections/Can.adoc[Can] container containing any matching instances for the given required type.

[#streamRegisteredBeansOfType_Class]
=== streamRegisteredBeansOfType(Class)

Streams all registered bean adapters implementing the requested type.

[#streamRegisteredBeans_]
=== streamRegisteredBeans()

Returns all bean adapters that have been registered.

[#lookupRegisteredBeanById_LogicalType]
=== lookupRegisteredBeanById(LogicalType)

Returns a registered bean of given _name_ .

[#lookupRegisteredBeanByIdElseFail_LogicalType]
=== lookupRegisteredBeanByIdElseFail(LogicalType)

Returns a registered bean of given _name_ , or throws when no such bean.

[#lookupService_Class]
=== lookupService(Class)

Returns a domain service implementing the requested type.

If this lookup is ambiguous, the service annotated with highest priority is returned. see _jakarta.annotation.Priority_

[#lookupService_Class_Comparator]
=== lookupService(Class, Comparator)

Returns a domain service implementing the requested type.

If this lookup is ambiguous, then the provided comparator is used.

[#lookupServiceElseFail_Class]
=== lookupServiceElseFail(Class)

Looks up a domain service of the requested type (same as _#lookupService(Class)_ ) but throws a _NoSuchElementException_ if there are no such instances.

[#clearRegisteredBeans_]
=== clearRegisteredBeans()

Invalidates any cached service adapters that might hold a reference to the current _org.apache.causeway.core.metamodel.specloader.SpecificationLoader_ . Particularly useful when discarding a meta-model instance, that is, purging the _org.apache.causeway.core.metamodel.spec.ObjectSpecification_ cache.

include::hooks/ServiceRegistry_010-implementation.adoc[]

include::hooks/ServiceRegistry_020-examples-and-usage.adoc[]
