Package 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.

  • Constructor Details

    • ValueChangeEvent

      protected ValueChangeEvent(T value)
      Creates a value change event.
      Parameters:
      value - the value

  • Method Details

    • 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 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: