CDI APIs 2.0 · javax.enterprise.inject.Instance

Allows the application to dynamically obtain instances of beans with a specified combination of required type and qualifiers.

In certain situations, injection is not the most convenient way to obtain a contextual reference. For example, it may not be used when:

the bean type or qualifiers vary dynamically at runtime, or
depending upon the deployment, there may be no bean which satisfies the type and qualifiers, or
we would like to iterate over all beans of a certain type.

In these situations, an instance of the Instance may be injected:

@Inject
Instance<PaymentProcessor> paymentProcessor;

Any combination of qualifiers may be specified at the injection point:

@Inject
@PayBy(CHEQUE)
Instance<PaymentProcessor> chequePaymentProcessor;

Or, the @Any qualifier may be used, allowing the application to specify qualifiers dynamically:

@Inject
@Any
Instance<PaymentProcessor> anyPaymentProcessor;

Finally, the @New qualifier may be used, allowing the application to obtain a @New qualified bean:

@Inject
@New(ChequePaymentProcessor.class)
Instance<PaymentProcessor> chequePaymentProcessor;

For an injected Instance:

the required type is the type parameter specified at the injection point, and
the required qualifiers are the qualifiers specified at the injection point.

The inherited javax.inject.Provider#get() method returns a contextual references for the unique bean that matches the required type and required qualifiers and is eligible for injection into the class into which the parent Instance was injected, or throws an javax.enterprise.inject.UnsatisfiedResolutionException or javax.enterprise.inject.AmbiguousResolutionException.

PaymentProcessor pp = chequePaymentProcessor.get();

The inherited java.lang.Iterable#iterator() method returns an iterator over contextual references for beans that match the required type and required qualifiers and are eligible for injection into the class into which the parent Instance was injected.

for (PaymentProcessor pp : anyPaymentProcessor)
    pp.test();

Method Summary

Modifier and Type	Method and Description
public void	destroy(T the instance to destroy instance) When called, the container destroys the instance if the active context object for the scope type of the bean supports destroying bean instances.
public boolean	Returns: `true` if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise. isAmbiguous() Determines if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected.
public default boolean	Returns: `true` if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise. isResolvable() Determines if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected.
public boolean	Returns: `true` if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise. isUnsatisfied() Determines if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected.
public Instance<T>	Returns: the child `Instance` select(Annotation... the additional required qualifiers qualifiers) Obtains a child `Instance` for the given additional required qualifiers.
public < the required type U extends T> Instance<U>	Returns: the child `Instance` select(Class<U> a `java.lang.Class` representing the required type subtype, Annotation... the additional required qualifiers qualifiers) Obtains a child `Instance` for the given required type and additional required qualifiers.
public < the required type U extends T> Instance<U>	Returns: the child `Instance` select(TypeLiteral<U> a `javax.enterprise.util.TypeLiteral` representing the required type subtype, Annotation... the additional required qualifiers qualifiers) Obtains a child `Instance` for the given required type and additional required qualifiers.
public default Stream<T>	Returns: a `Stream` representing the beans associated with this `Instance` object stream() When called, provides back a Stream of the beans available in this Instance.

Inherited from java.lang.Iterable:: forEach iterator spliterator
Inherited from javax.inject.Provider:: get

Method Detail

destroy back to summary

destroy	back to summary
public void destroy(T instance) When called, the container destroys the instance if the active context object for the scope type of the bean supports destroying bean instances. All normal scoped built-in contexts support destroying bean instances. The instance passed should either be a dependent scoped bean instance obtained from the same `Instance` object, or the client proxy for a normal scoped bean instance. Parameters instance:T the instance to destroy Exceptions UnsupportedOperationException: if the active context object for the scope type of the bean does not support destroying bean instances Since 1.1

public void destroy(T instance)

When called, the container destroys the instance if the active context object for the scope type of the bean supports destroying bean instances. All normal scoped built-in contexts support destroying bean instances.

The instance passed should either be a dependent scoped bean instance obtained from the same Instance object, or the client proxy for a normal scoped bean instance.

Parameters

instance:T: the instance to destroy

Exceptions

UnsupportedOperationException:: if the active context object for the scope type of the bean does not support destroying bean instances

Since

1.1

isAmbiguous back to summary

isAmbiguous	back to summary
public boolean isAmbiguous() Determines if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected. Returns:boolean `true` if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise.

public boolean isAmbiguous()

Determines if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected.

Returns:boolean: true if there is more than one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected, or false otherwise.

isResolvable back to summary

isResolvable	back to summary
public default boolean isResolvable() Determines if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected. Returns:boolean `true` if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise. Since 2.0

public default boolean isResolvable()

Determines if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected.

Returns:boolean: true if there is exactly one bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected, or false otherwise.
Since: 2.0

isUnsatisfied back to summary

isUnsatisfied	back to summary
public boolean isUnsatisfied() Determines if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected. Returns:boolean `true` if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent `Instance` was injected, or `false` otherwise.

public boolean isUnsatisfied()

Determines if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected.

Returns:boolean: true if there is no bean that matches the required type and qualifiers and is eligible for injection into the class into which the parent Instance was injected, or false otherwise.

select back to summary

select	back to summary
public Instance<T> select(Annotation... qualifiers) Obtains a child `Instance` for the given additional required qualifiers. Parameters qualifiers:Annotation[] the additional required qualifiers Returns:Instance<T> the child `Instance` Exceptions IllegalArgumentException: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type IllegalStateException: if the container is already shutdown

public Instance<T> select(Annotation... qualifiers)

Obtains a child Instance for the given additional required qualifiers.

Parameters

qualifiers:Annotation[]: the additional required qualifiers

Returns:Instance<T>

the child Instance

Exceptions

IllegalArgumentException:: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type
IllegalStateException:: if the container is already shutdown

select back to summary

select	back to summary
public <U extends T> Instance<U> select(Class<U> subtype, Annotation... qualifiers) Obtains a child `Instance` for the given required type and additional required qualifiers. Parameters <U> the required type subtype:Class<U> a `java.lang.Class` representing the required type qualifiers:Annotation[] the additional required qualifiers Returns:Instance<U> the child `Instance` Exceptions IllegalArgumentException: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type IllegalStateException: if the container is already shutdown

public Instance select(Class subtype, Annotation... qualifiers)

Obtains a child Instance for the given required type and additional required qualifiers.

Parameters

: the required type
subtype:Class: a java.lang.Class representing the required type
qualifiers:Annotation[]: the additional required qualifiers

Returns:Instance

the child Instance

Exceptions

IllegalArgumentException:: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type
IllegalStateException:: if the container is already shutdown

select back to summary

select	back to summary
public <U extends T> Instance<U> select(TypeLiteral<U> subtype, Annotation... qualifiers) Obtains a child `Instance` for the given required type and additional required qualifiers. Parameters <U> the required type subtype:TypeLiteral<U> a `javax.enterprise.util.TypeLiteral` representing the required type qualifiers:Annotation[] the additional required qualifiers Returns:Instance<U> the child `Instance` Exceptions IllegalArgumentException: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type IllegalStateException: if the container is already shutdown

public Instance select(TypeLiteral subtype, Annotation... qualifiers)

Obtains a child Instance for the given required type and additional required qualifiers.

Parameters

: the required type
subtype:TypeLiteral: a javax.enterprise.util.TypeLiteral representing the required type
qualifiers:Annotation[]: the additional required qualifiers

Returns:Instance

the child Instance

Exceptions

IllegalArgumentException:: if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type
IllegalStateException:: if the container is already shutdown

stream back to summary

stream	back to summary
public default Stream<T> stream() When called, provides back a Stream of the beans available in this Instance. If no beans are found, it returns an empty stream. Returns:Stream<T> a `Stream` representing the beans associated with this `Instance` object Since 2.0

public default Stream<T> stream()

When called, provides back a Stream of the beans available in this Instance. If no beans are found, it returns an empty stream.

Returns:Stream<T>: a Stream representing the beans associated with this Instance object
Since: 2.0

public Interface Instance<T>

Method Summary

Method Detail