Package com.vaadin.flow.component

Class ComponentEventBus

java.lang.Object

com.vaadin.flow.component.ComponentEventBus

All Implemented Interfaces:

Serializable

public class ComponentEventBus
extends Object
implements Serializable

An event bus for Components.

Handles adding and removing event listeners, and firing events of type ComponentEvent.

Events can either be fired manually through fireEvent(ComponentEvent) or automatically based on a DOM event (see DomEvent). Automatically fired events must have a suitable constructor, as defined in DomEvent.

Since:

1.0

Author:

Vaadin Ltd

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
ComponentEventBus(Component component)	Creates an event bus for the given component.

Method Summary

Modifier and Type	Method	Description
<T extends ComponentEvent<?>> Registration	addListener(Class<T> eventType, ComponentEventListener<T> listener)	Adds a listener for the given event type.
<T extends ComponentEvent<?>> Registration	addListener(Class<T> eventType, ComponentEventListener<T> listener, Consumer<DomListenerRegistration> domListenerConsumer)	Adds a listener for the given event type, and customizes the corresponding DOM event listener with the given consumer.
void	fireEvent(ComponentEvent event)	Dispatches the event to all listeners registered for the event type.
Collection<?>	getListeners(Class<? extends ComponentEvent> eventType)	Returns all listeners that match or extend the given event type.
boolean	hasListener(Class<? extends ComponentEvent> eventType)	Checks if there is at least one listener registered for the given event type.

Methods inherited from class java.lang.Object

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

Constructor Details

ComponentEventBus

public ComponentEventBus(Component component)

Creates an event bus for the given component.

Parameters:

component - the component which will be used as a source for all fired events

Method Details

addListener

public <T extends ComponentEvent<?>> Registration addListener(Class<T> eventType,
 ComponentEventListener<T> listener)

Adds a listener for the given event type.

Type Parameters:

T - the event type

Parameters:

eventType - the event type for which to call the listener

listener - the listener to call when the event occurs

Returns:

an object which can be used to remove the event listener

addListener

public <T extends ComponentEvent<?>> Registration addListener(Class<T> eventType,
 ComponentEventListener<T> listener,
 Consumer<DomListenerRegistration> domListenerConsumer)

Adds a listener for the given event type, and customizes the corresponding DOM event listener with the given consumer. This allows overriding eg. the debounce settings defined in the DomEvent annotation.

Note that customizing the DOM event listener works only for event types which are annotated with DomEvent. Use addListener(Class, ComponentEventListener) for other listeners, or if you don't need to customize the DOM listener.

Type Parameters:

T - the event type

Parameters:

eventType - the event type for which to call the listener, must be annotated with DomEvent

listener - the listener to call when the event occurs

domListenerConsumer - a consumer to customize the behavior of the DOM event listener, not null

Returns:

an object which can be used to remove the event listener

Throws:

IllegalArgumentException - if the event type is not annotated with DomEvent

hasListener

public boolean hasListener(Class<? extends ComponentEvent> eventType)

Checks if there is at least one listener registered for the given event type.

Parameters:

eventType - the component event type

Returns:

true if at least one listener is registered, false otherwise

getListeners

public Collection<?> getListeners(Class<? extends ComponentEvent> eventType)

Returns all listeners that match or extend the given event type.

Parameters:

eventType - the component event type

Returns:

A collection with all registered listeners for a given event type. Empty if no listeners are found.

fireEvent

public void fireEvent(ComponentEvent event)

Dispatches the event to all listeners registered for the event type.

Parameters:

event - the event to fire