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Events

Definition

Any object can be used as an event, but it's good practice to use standardized event classes. Events can be small, large, simple, or very complex. Anything goes!

A few example event classes:

public class EmptyEvent {

}

public class MessageEvent {

    private String message;

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

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

public class SunEvent {

    private final String description;

    public SunEvent(String description) {
        this.description = description;
    }

    public String getDescription() {
        return message;
    }

    public static class SunriseEvent extends SunEvent {

        public SunriseEvent() {
            super("The sun rises");
        }
    }

    public static class SunsetEvent extends SunEvent {

        public SunsetEvent() {
            super("The sun sets");
        }
    }
}

Dispatching

To dispatch an event, call one of the dispatch methods defined in EventBus, passing your event as a parameter.

MessageEvent event = new MessageEvent("world greetings");

EVENT_BUS.dispatch(event);

Status Event

A status event can be suppressed or terminated, and the StatusEvent class and IStatusEvent interface provide methods to manipulate and check their status.

Status Definitions

Possible statuses are defined by the IStatusEvent.EventStatus enum.

Value Description
ALIVE The event is active and not suppressed or terminated.
SUPPRESSED The event is suppressed. A suppressed event may become unsuppressed.
TERMINATED The event is terminated and cannot be altered further.

Event Bus Interaction

When a Status Event is dispatched, the dispatch method will return true if the event was suppressed or terminated by any listener.

if (eventBus.dispatch(new StatusEvent())) {
    System.out.println("Event was suppressed or terminated");
} else {
    System.out.println("Event is still alive");
}

Defining a Status Event

Extend the StatusEvent class. 

public class Event extends StatusEvent {

}
Completely functional out of the box, this is the recommended approach.

If you need custom functionality, implement the IStatusEvent interface. 

public class Event implements IStatusEvent {

    private EventStatus status;

    @NotNull
    @Override
    public EventStatus getEventStatus() {
        return status;
    }

    @Override
    public void setEventStatus(@NotNull EventStatus status) {
        this.status = status;
    }

    @Override
    public boolean isSuppressed() {
        return status == EventStatus.SUPPRESSED;
    }

    @Override
    public boolean isTerminated() {
        return status == EventStatus.TERMINATED;
    }
}

Warning

It's recommended not to call setEventStatus() outside of the status event itself, even in your own implementations.