ValueChangeEvent (GWT Javadoc)

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GWT 2.7.0

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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>>
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
`protected`	`ValueChangeEvent(T value)` Creates a value change event.

Method Summary

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()