Targets¶

A Target determines if a given class matches the target class according to its targeting rule.

This can be used dispatch events to specific listeners or listen to specific events.

Definition¶

Usage Examples¶

Dispatch TargetsListener Targets

In this example, listeners are listening to all events, & will print the word "Hi" when they handle an event.

Setup details.

EventBus eventBus = new EventBus();
eventBus.register(new MyListener());
eventBus.register(new MyExtendedListener());
eventBus.register(new OtherListener());

(MyExtendedListener extends MyListener.)

If we dispatch our event normally, "Hi" will be printed 3 times.

eventBus.dispatch(new MyEvent());

If we fine target MyListener.class, "Hi" will only be printed 1 time because neither MyExtendedListener nor OtherListener are included in this target.

eventBus.dispatch(new MyEvent(), Target.fine(MyListener.class));

However, if we cascade target MyListener.class, "Hi" will be printed 2 times because MyExtendedListener extends MyListener.

eventBus.dispatch(new MyEvent(), Target.cascade(MyListener.class));

In this example, listeners are listening to all events, & will print the word "Hi" when they handle an event.

Setup details.

Event bus setup.

EventBus eventBus = new EventBus();

Target target = // ...

eventBus.register(new MyListener(target));

eventBus.dispatch(new MyEvent("hi"));
eventBus.dispatch(new MyEvent.MyExtendedEvent("hi"));
eventBus.dispatch(new OtherEvent("hi"));

(MyExtendedEvent extends MyEvent.)

MyListener class.

public class MyListener extends EventListener<MyEvent> {

    public MyListener(Target target) {
        super(target);
    }

    @Override
    public void invoke(MyEvent event) {
        System.out.println(event.message());
    }
}

MyEvent class.

public class MyEvent {

    private final String message;

    public MyEvent(String message) {
        this.message = message;
    }

    public String message() {
        return message;
    }

    public static class MyExtendedEvent extends MyEvent {

        public MyExtendedEvent(String message) {
            super(message);
        }
    }
}

If we listen with a target of all(), "Hi" will be printed 3 times.

Target.all()

If we fine target MyEvent.class, "Hi" will only be printed 1 time because neither MyExtendedEvent nor OtherEvent are included in this target.

Target.fine(MyListener.class)

However, if we cascade target MyEvent.class, "Hi" will be printed 2 times because MyExtendedEvent extends MyEvent.

Target.cascade(MyListener.class)