com.gwtplatform.dispatch.annotation

Annotation Type GenEvent

@Target(value=TYPE)
@Retention(value=SOURCE)
@Inherited
public @interface GenEvent

Annotation to generate Event and Handler classes.

If you type:

 
 @GenEvent
 public class FooChanged {
  Foo foo;
  boolean originator;
 }
 
 

gwt-platform will generate two classes, FooChangedEvent and FooChangedHandler.

FooChangedEvent will have fields, getters, and a constructor for foo and originator, plus static getType(), instance dispatch, etc., for it to function correctly as a GwtEvent.

FooChangedHandler will be an interface with a onFooChanged method that takes a FooChangedEvent parameter.

Notes:

There is no naming requirement for your class name. It will be appended with Event and Handler.

Using @Order:

The order the the fields can be optionally specified using the @Order annotation. If @Order is not used, then the order of the parameters to the constructor and to fire() is undefined.

If you type:

 
 @GenEvent
 public class FooChanged {
   @Order(1) Foo foo;
   @Order(2) int bar;
   @Order(3) boolean originator;
 }
 
 

The following constructor and fire methods will be generated:

 
  ...
  FooChangedEvent(Foo foo, int bar, boolean originator)
  ...
  public static void fire(HasEventBus source, Foo foo, int bar, boolean originator)
  ...
 
 

Omitting the @Order annotations would yield:

 
  ...
  FooChangedEvent(int bar, Foo foo, boolean originator)
  ...
  public static void fire(HasEventBus source, int bar, Foo foo, boolean originator)
  ...
 
 

Using @Optional:

If @Optional is used together with @GenEvent, an additional fire method is generated. If you type:

 
 @GenEvent
 public class FooChanged {
  @Optional @Order(1) Foo foo;
  @Order(2) int bar;
  @Optional @Order(3) boolean originator;
 }
 
 

The following constructors and fire methods will be generated:

 
  ...
  FooChangedEvent(int bar)
  FooChangedEvent(Foo foo, int bar, boolean originator)
  ...
  public static void fire(HasEventBus source, int bar)
  public static void fire(HasEventBus source, Foo foo, int bar, boolean originator)
  ...
 
 

Author:

Brendan Doherty, Florian Sauter, Stephen Haberman (concept)