Package org.djutils.event

Interface EventProducerInterface

All Known Subinterfaces:

RemoteEventProducerInterface

All Known Implementing Classes:

EventProducer, EventProducerImpl, EventProducingCollection, EventProducingIterator, EventProducingList, EventProducingListIterator, EventProducingMap, EventProducingSet, RemoteEventProducer

public interface EventProducerInterface

The EventProducerInterface defines the registration operations of an event producer. This behavior includes adding and removing listeners for a specific event type. The EventListener and EventProducer together form a combination of the Publish-Subscribe design pattern and the Observer design pattern using the notify(event) method. See https://en.wikipedia.org/wiki/Publish-subscribe_pattern, https://en.wikipedia.org/wiki/Observer_pattern, and https://howtodoinjava.com/design-patterns/behavioral/observer-design-pattern/.

Copyright (c) 2002-2021 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djutils.org. The DJUTILS project is distributed under a three-clause BSD-style license, which can be found at https://djutils.org/docs/license.html. This class was originally part of the DSOL project, see https://simulation.tudelft.nl/dsol/manual.

Author:

Peter Jacobs , Alexander Verbraeck

Field Summary

Fields

Modifier and Type	Field	Description
static int	FIRST_POSITION	The FIRST_POSITION in the queue.
static int	LAST_POSITION	The LAST_POSITION in the queue.

Method Summary

Modifier and Type	Method	Description
boolean	addListener(EventListenerInterface listener, EventTypeInterface eventType)	Add a listener as strong reference to the BEGINNING of a queue of listeners.
boolean	addListener(EventListenerInterface listener, EventTypeInterface eventType, int position)	Add a listener as strong reference to the specified position of a queue of listeners.
boolean	addListener(EventListenerInterface listener, EventTypeInterface eventType, int position, ReferenceType referenceType)	Add a listener to the specified position of a queue of listeners.
boolean	addListener(EventListenerInterface listener, EventTypeInterface eventType, ReferenceType referenceType)	Add a listener to the BEGINNING of a queue of listeners.
Set<EventTypeInterface>	getEventTypesWithListeners()	Return the EventTypeInterfaces for which the EventProducer has listeners.
Serializable	getSourceId()	Provide the sourceId that will be transmitted with the fired Event.
boolean	hasListeners()	Return whether the EventProducer has listeners.
int	numberOfListeners(EventTypeInterface eventType)	Return the number of listeners for the provided EventTypeInterface.
boolean	removeListener(EventListenerInterface listener, EventTypeInterface eventType)	Remove the subscription of a listener for a specific event.

Field Detail

FIRST_POSITION

static final int FIRST_POSITION

The FIRST_POSITION in the queue.

See Also:

Constant Field Values

LAST_POSITION

static final int LAST_POSITION

The LAST_POSITION in the queue.

See Also:

Constant Field Values

Method Detail

getSourceId

Serializable getSourceId()
                  throws RemoteException

Provide the sourceId that will be transmitted with the fired Event.

Returns:

Serializable; the sourceId that will be transmitted with the fired Event

Throws:

RemoteException - if a network failure occurs

addListener

boolean addListener(EventListenerInterface listener,
                    EventTypeInterface eventType)
             throws RemoteException

Add a listener as strong reference to the BEGINNING of a queue of listeners.

Parameters:

listener - EventListenerInterface; the listener which is interested at events of eventType

eventType - EventTypeInterface; the events of interest

Returns:

the success of adding the listener. If a listener was already added false is returned

Throws:

RemoteException - If a network connection failure occurs.

addListener

boolean addListener(EventListenerInterface listener,
                    EventTypeInterface eventType,
                    ReferenceType referenceType)
             throws RemoteException

Add a listener to the BEGINNING of a queue of listeners.

Parameters:

listener - EventListenerInterface; the listener which is interested at events of eventType

eventType - EventTypeInterface; the events of interest

referenceType - ReferenceType; whether the listener is added as a strong or as a weak reference

Returns:

the success of adding the listener. If a listener was already added false is returned

Throws:

RemoteException - If a network connection failure occurs.

See Also:

WeakReference

addListener

boolean addListener(EventListenerInterface listener,
                    EventTypeInterface eventType,
                    int position)
             throws RemoteException

Add a listener as strong reference to the specified position of a queue of listeners.

Parameters:

listener - EventListenerInterface; the listener which is interested at events of eventType

eventType - EventTypeInterface; the events of interest

position - int; the position of the listener in the queue

Returns:

the success of adding the listener. If a listener was already added, or an illegal position is provided false is returned

Throws:

RemoteException - If a network connection failure occurs.

addListener

boolean addListener(EventListenerInterface listener,
                    EventTypeInterface eventType,
                    int position,
                    ReferenceType referenceType)
             throws RemoteException

Add a listener to the specified position of a queue of listeners.

Parameters:

listener - EventListenerInterface; which is interested at certain events

eventType - EventTypeInterface; the events of interest

position - int; the position of the listener in the queue

referenceType - ReferenceType; whether the listener is added as a strong or as a weak reference

Returns:

the success of adding the listener. If a listener was already added or an illegal position is provided false is returned

Throws:

RemoteException - If a network connection failure occurs.

See Also:

WeakReference

removeListener

boolean removeListener(EventListenerInterface listener,
                       EventTypeInterface eventType)
                throws RemoteException

Remove the subscription of a listener for a specific event.

Parameters:

listener - EventListenerInterface; which is no longer interested

eventType - EventTypeInterface; the event which is of no interest any more

Returns:

the success of removing the listener. If a listener was not subscribed false is returned

Throws:

RemoteException - If a network connection failure occurs.

hasListeners

boolean hasListeners()
              throws RemoteException

Return whether the EventProducer has listeners.

Returns:

boolean; whether the EventProducer has listeners or not

Throws:

RemoteException - If a network connection failure occurs.

numberOfListeners

int numberOfListeners(EventTypeInterface eventType)
               throws RemoteException

Return the number of listeners for the provided EventTypeInterface.

Parameters:

eventType - EventTypeInterface; the event type to return the number of listeners for

Returns:

boolean; whether the EventProducer has listeners or not

Throws:

RemoteException - If a network connection failure occurs.

getEventTypesWithListeners

Set<EventTypeInterface> getEventTypesWithListeners()
                                            throws RemoteException

Return the EventTypeInterfaces for which the EventProducer has listeners.

Returns:

Set<EventTypeInterface>; the EventTypeInterfaces for which the EventProducer has registered listeners

Throws:

RemoteException - If a network connection failure occurs.