Module jakarta.cdi

Package jakarta.enterprise.event

Interface Event<T>

Type Parameters:

T - the type of the event object

public interface Event<T>

Allows the application to fire events of a particular type.

Beans fire events via an instance of the Event interface, which may be injected:

 @Inject
 @Any
 Event<LoggedInEvent> loggedInEvent;
 

The fire() method accepts an event object:

 public void login() { 
    ...
    loggedInEvent.fire( new LoggedInEvent(user) );
 }
 

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

 @Inject
 @Admin
 Event<LoggedInEvent> adminLoggedInEvent;
 

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

 @Inject
 @Any
 Event<LoggedInEvent> loggedInEvent;
 

For an injected Event:

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

Events may also be fired asynchronously with fireAsync(Object) and fireAsync(Object, NotificationOptions) methods

Author:

Gavin King, Pete Muir, David Allen, Antoine Sabot-Durand

Method Summary

Modifier and Type	Method	Description
void	fire(T event)	Fires an event with the specified qualifiers and notifies observers.
<U extends T> java.util.concurrent.CompletionStage<U>	fireAsync(U event)	Fires an event asynchronously with the specified qualifiers and notifies asynchronous observers.
<U extends T> java.util.concurrent.CompletionStage<U>	fireAsync(U event, NotificationOptions options)	Fires an event asynchronously with the specified qualifiers and notifies asynchronous observers.
<U extends T> Event<U>	select(TypeLiteral<U> subtype, java.lang.annotation.Annotation... qualifiers)	Obtains a child Event for the given required type and additional required qualifiers.
Event<T>	select(java.lang.annotation.Annotation... qualifiers)	Obtains a child Event for the given additional required qualifiers.
<U extends T> Event<U>	select(java.lang.Class<U> subtype, java.lang.annotation.Annotation... qualifiers)	Obtains a child Event for the given required type and additional required qualifiers.

Method Detail

fire

void fire(T event)

Fires an event with the specified qualifiers and notifies observers.

Parameters:

event - the event object

Throws:

java.lang.IllegalArgumentException - if the runtime type of the event object contains a type variable

ObserverException - if a notified observer throws a checked exception, it will be wrapped and rethrown as an (unchecked) ObserverException

fireAsync

<U extends T> java.util.concurrent.CompletionStage<U> fireAsync(U event)

Fires an event asynchronously with the specified qualifiers and notifies asynchronous observers.

Type Parameters:

U - event type

Parameters:

event - the event object

Returns:

a CompletionStage allowing further pipeline composition on the asynchronous operation. Default asynchronous execution facility is container specific. If any observer notified by this event throws an exception then the resulting CompletionStage is completed exceptionally with CompletionException that wraps all the exceptions raised by observers as suppressed exception. If no exception is thrown by observers then the resulting CompletionStage is completed normally with the event payload.

Throws:

java.lang.IllegalArgumentException - if the runtime type of the event object contains a type variable

Since:

2.0

fireAsync

<U extends T> java.util.concurrent.CompletionStage<U> fireAsync(U event,
                                                                NotificationOptions options)

Fires an event asynchronously with the specified qualifiers and notifies asynchronous observers. A custom Executor will be used to make asynchronous calls

Type Parameters:

U - event type

Parameters:

event - the event object

options - the notification options

Returns:

a CompletionStage allowing further pipeline composition on the asynchronous operation. Default asynchronous execution facility is container specific. If any observer notified by this event throws an exception then the resulting CompletionStage is completed exceptionally with CompletionException that wraps all the exceptions raised by observers as suppressed exception. If no exception is thrown by observers then the resulting CompletionStage is completed normally with the event payload.

Throws:

java.lang.IllegalArgumentException - if the runtime type of the event object contains a type variable

Since:

2.0

select

Event<T> select(java.lang.annotation.Annotation... qualifiers)

Obtains a child Event for the given additional required qualifiers.

Parameters:

qualifiers - the additional specified qualifiers

Returns:

the child Event

Throws:

java.lang.IllegalArgumentException - if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type

select

<U extends T> Event<U> select(java.lang.Class<U> subtype,
                              java.lang.annotation.Annotation... qualifiers)

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

Type Parameters:

U - the specified type

Parameters:

subtype - a Class representing the specified type

qualifiers - the additional specified qualifiers

Returns:

the child Event

Throws:

java.lang.IllegalArgumentException - if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type

select

<U extends T> Event<U> select(TypeLiteral<U> subtype,
                              java.lang.annotation.Annotation... qualifiers)

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

Type Parameters:

U - the specified type

Parameters:

subtype - a TypeLiteral representing the specified type

qualifiers - the additional specified qualifiers

Returns:

the child Event

Throws:

java.lang.IllegalArgumentException - if passed two instances of the same non repeating qualifier type, or an instance of an annotation that is not a qualifier type