com.google.gwt.event.shared

Class HandlerManager

java.lang.Object

com.google.gwt.event.shared.HandlerManager

All Implemented Interfaces:

HasHandlers

public class HandlerManager
extends Object
implements HasHandlers

Manager responsible for adding handlers to event sources and firing those handlers on passed in events. Primitive ancestor of EventBus, and used at the core of {com.google.gwt.user.client.ui.Widget}.

While widget authors should continue to use Widget.addDomHandler(EventHandler, com.google.gwt.event.dom.client.DomEvent.Type) and Widget.addHandler(EventHandler, com.google.gwt.event.shared.GwtEvent.Type) , application developers are strongly discouraged from using a HandlerManager instance as a global event dispatch mechanism.

Constructor Summary

Constructors

Constructor and Description
HandlerManager(Object source) Creates a handler manager with a source to be set on all events fired via fireEvent(GwtEvent).
HandlerManager(Object source, boolean fireInReverseOrder) Creates a handler manager with the given source, specifying the order in which handlers are fired.

Method Summary

Modifier and Type	Method and Description
<H extends EventHandler> HandlerRegistration	addHandler(GwtEvent.Type<H> type, H handler) Adds a handler.
void	fireEvent(GwtEvent<?> event) Fires the given event to the handlers listening to the event's type.
<H extends EventHandler> H	getHandler(GwtEvent.Type<H> type, int index) Gets the handler at the given index.
int	getHandlerCount(GwtEvent.Type<?> type) Gets the number of handlers listening to the event type.
boolean	isEventHandled(GwtEvent.Type<?> e) Does this handler manager handle the given event type?
<H extends EventHandler> void	removeHandler(GwtEvent.Type<H> type, H handler) Removes the given handler from the specified event type.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Constructor Detail

HandlerManager

public HandlerManager(Object source)

Creates a handler manager with a source to be set on all events fired via fireEvent(GwtEvent). Handlers will be fired in the order that they are added.

Parameters:

source - the default event source

HandlerManager

public HandlerManager(Object source,
                      boolean fireInReverseOrder)

Creates a handler manager with the given source, specifying the order in which handlers are fired.

Parameters:

source - the event source

fireInReverseOrder - true to fire handlers in reverse order

Method Detail

addHandler

public <H extends EventHandler> HandlerRegistration addHandler(GwtEvent.Type<H> type,
                                                               H handler)

Adds a handler.

Type Parameters:

H - The type of handler

Parameters:

type - the event type associated with this handler

handler - the handler

Returns:

the handler registration, can be stored in order to remove the handler later

fireEvent

public void fireEvent(GwtEvent<?> event)

Fires the given event to the handlers listening to the event's type.

Any exceptions thrown by handlers will be bundled into a UmbrellaException and then re-thrown after all handlers have completed. An exception thrown by a handler will not prevent other handlers from executing.

Note, any subclass should be very careful about overriding this method, as adds/removes of handlers will not be safe except within this implementation.

Specified by:

fireEvent in interface HasHandlers

Parameters:

event - the event

getHandler

public <H extends EventHandler> H getHandler(GwtEvent.Type<H> type,
                                             int index)

Gets the handler at the given index.

Type Parameters:

H - the event handler type

Parameters:

index - the index

type - the handler's event type

Returns:

the given handler

getHandlerCount

public int getHandlerCount(GwtEvent.Type<?> type)

Gets the number of handlers listening to the event type.

Parameters:

type - the event type

Returns:

the number of registered handlers

isEventHandled

public boolean isEventHandled(GwtEvent.Type<?> e)

Does this handler manager handle the given event type?

Parameters:

e - the event type

Returns:

whether the given event type is handled

removeHandler

public <H extends EventHandler> void removeHandler(GwtEvent.Type<H> type,
                                                   H handler)

Removes the given handler from the specified event type.

Type Parameters:

H - handler type

Parameters:

type - the event type

handler - the handler