com.google.gwt.event.logical.shared

Class ValueChangeEvent<T>

java.lang.Object

com.google.web.bindery.event.shared.Event<H>

com.google.gwt.event.shared.GwtEvent<ValueChangeHandler<T>>

com.google.gwt.event.logical.shared.ValueChangeEvent<T>

Type Parameters:

T - the value about to be changed

Direct Known Subclasses:

DateChangeEvent

public class ValueChangeEvent<T>
extends GwtEvent<ValueChangeHandler<T>>

Represents a value change event.

Nested Class Summary

Nested classes/interfaces inherited from class com.google.gwt.event.shared.GwtEvent

GwtEvent.Type<H>

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ValueChangeEvent(T value) Creates a value change event.

Method Summary

Modifier and Type	Method and Description
protected void	dispatch(ValueChangeHandler<T> handler) Should only be called by HandlerManager.
static <T> void	fire(HasValueChangeHandlers<T> source, T value) Fires a value change event on all registered handlers in the handler manager.
static <T> void	fireIfNotEqual(HasValueChangeHandlers<T> source, T oldValue, T newValue) Fires value change event if the old value is not equal to the new value.
GwtEvent.Type<ValueChangeHandler<T>>	getAssociatedType() Returns the Event.Type used to register this event, allowing an EventBus to find handlers of the appropriate class.
static GwtEvent.Type<ValueChangeHandler<?>>	getType() Gets the type associated with this event.
T	getValue() Gets the value.
protected static <T> boolean	shouldFire(HasValueChangeHandlers<T> source, T oldValue, T newValue) Convenience method to allow subtypes to know when they should fire a value change event in a null-safe manner.
java.lang.String	toDebugString() This is a method used primarily for debugging.

Methods inherited from class com.google.gwt.event.shared.GwtEvent

assertLive, getSource, isLive, kill, revive

Methods inherited from class com.google.web.bindery.event.shared.Event

setSource, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueChangeEvent

protected ValueChangeEvent(T value)

Creates a value change event.

Parameters:

value - the value

Method Detail

fire

public static <T> void fire(HasValueChangeHandlers<T> source,
                            T value)

Fires a value change event on all registered handlers in the handler manager. If no such handlers exist, this method will do nothing.

Type Parameters:

T - the old value type

Parameters:

source - the source of the handlers

value - the value

fireIfNotEqual

public static <T> void fireIfNotEqual(HasValueChangeHandlers<T> source,
                                      T oldValue,
                                      T newValue)

Fires value change event if the old value is not equal to the new value. Use this call rather than making the decision to short circuit yourself for safe handling of null.

Type Parameters:

T - the old value type

Parameters:

source - the source of the handlers

oldValue - the oldValue, may be null

newValue - the newValue, may be null

getType

public static GwtEvent.Type<ValueChangeHandler<?>> getType()

Gets the type associated with this event.

Returns:

returns the handler type

shouldFire

protected static <T> boolean shouldFire(HasValueChangeHandlers<T> source,
                                        T oldValue,
                                        T newValue)

Convenience method to allow subtypes to know when they should fire a value change event in a null-safe manner.

Type Parameters:

T - value type

Parameters:

source - the source

oldValue - the old value

newValue - the new value

Returns:

whether the event should be fired

getAssociatedType

public final GwtEvent.Type<ValueChangeHandler<T>> getAssociatedType()

Description copied from class: Event

Returns the Event.Type used to register this event, allowing an EventBus to find handlers of the appropriate class.

Specified by:

getAssociatedType in class GwtEvent<ValueChangeHandler<T>>

Returns:

the type

getValue

public T getValue()

Gets the value.

Returns:

the value

toDebugString

public java.lang.String toDebugString()

Description copied from class: Event

This is a method used primarily for debugging. It gives a string representation of the event details. This does not override the toString method because the compiler cannot always optimize toString out correctly. Event types should override as desired.

Overrides:

toDebugString in class Event<ValueChangeHandler<T>>

Returns:

a string representing the event's specifics.

dispatch

protected void dispatch(ValueChangeHandler<T> handler)

Description copied from class: GwtEvent

Should only be called by HandlerManager. In other words, do not use or call.

Specified by:

dispatch in class GwtEvent<ValueChangeHandler<T>>

Parameters:

handler - handler

See Also:

EventBus.dispatchEvent(Event, Object)