public class

ValueChangeEvent

extends GwtEvent<H extends EventHandler>
java.lang.Object
   ↳ com.google.gwt.event.shared.GwtEvent<H extends com.google.gwt.event.shared.EventHandler>
     ↳ com.google.gwt.event.logical.shared.ValueChangeEvent<T>

Class Overview

Represents a value change event.

Summary

Protected Constructors
ValueChangeEvent(T value)
Creates a value change event.
Public Methods
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.
final Type<ValueChangeHandler<T>> getAssociatedType()
Returns the type used to register this event.
static Type<ValueChangeHandler<?>> getType()
Gets the type associated with this event.
T getValue()
Gets the value.
String toDebugString()
This is a method used primarily for debugging.
Protected Methods
void dispatch(ValueChangeHandler<T> handler)
Should only be called by HandlerManager.
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.
[Expand]
Inherited Methods
From class com.google.gwt.event.shared.GwtEvent
From class java.lang.Object

Protected Constructors

protected ValueChangeEvent (T value)

Creates a value change event.

Parameters
value the value

Public Methods

public static 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.

Parameters
source the source of the handlers
value the value

public static 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.

Parameters
source the source of the handlers
oldValue the oldValue, may be null
newValue the newValue, may be null

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

Returns the type used to register this event. Used by handler manager to dispatch events to the correct handlers.

Returns
  • the type

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

Gets the type associated with this event.

Returns
  • returns the handler type

public T getValue ()

Gets the value.

Returns
  • the value

public String toDebugString ()

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.

Returns
  • a string representing the event's specifics.

Protected Methods

protected void dispatch (ValueChangeHandler<T> handler)

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

Parameters
handler handler

protected static 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.

Parameters
source the source
oldValue the old value
newValue the new value
Returns
  • whether the event should be fired