Custom Events¶
You can write your own event classes and dispatch those events using the method described above. An event class must either implement the Event interface and, if it should be possible to cancel the event, Cancellable.
Tip
Depending on what type of event you want to create, there might be another interface to implement instead of
Event
. For example if your event describes something that happens to a Player, you should have your
custom event class implement TargetPlayerEvent.
Example: Custom Event Class¶
The following class describes an event indicating a Player
has come in contact with FLARD and is now about to
mutate in a way specified by the event. Since the event targets a player and can be cancelled by listeners, it
implements both the TargetPlayerEvent
and Cancellable
interfaces.
Since generally custom events are intended to be listened to by other plugins, it is in your best interest to document
them appropriately. This includes a list of objects typically found in the Cause. In the below example, it
would probably be mentioned that the root cause is generally an object of the fictitious FLARDSource
class.
import org.spongepowered.api.entity.living.player.Player;
import org.spongepowered.api.event.Cancellable;
import org.spongepowered.api.event.cause.Cause;
import org.spongepowered.api.event.entity.living.humanoid.player.TargetPlayerEvent;
public class PlayerMutationEvent implements TargetPlayerEvent, Cancellable {
public static enum Mutation {
COMPULSIVE_POETRY,
ROTTED_SOCKS,
SPONTANEOUS_COMBUSTION;
};
private final Cause cause;
private final Player victim;
private final Mutation mutation;
private boolean cancelled = false;
public PlayerMutationEvent(Player victim, Mutation mutation, Cause cause) {
this.victim = victim;
this.mutation = mutation;
this.cause = cause;
}
public Mutation getMutation() {
return this.mutation;
}
@Override
public boolean isCancelled() {
return this.cancelled;
}
@Override
public void setCancelled(boolean cancel) {
this.cancelled = cancel;
}
@Override
public Cause getCause() {
return this.cause;
}
@Override
public Player getTargetEntity() {
return this.victim;
}
}
Example: Fire Custom Event¶
import org.spongepowered.api.Sponge;
PlayerMutationEvent event = new PlayerMutationEvent(victim, PlayerMutationEvent.Mutation.ROTTED_SOCKS,
Cause.source(flardSource).build());
Sponge.getEventManager().post(event);
if (!event.isCancelled()) {
// Mutation code
}
Bear in mind that you need to supply a non-empty cause. If your event was Cancellable
, make sure that it was not
cancelled before performing the action described by the event.
Example: Listen for Custom Event¶
import org.spongepowered.api.event.Listener;
import org.spongepowered.api.text.Text;
@Listener
public void onPrivateMessage(PlayerMutationEvent event) {
if(event.getMutation() == PlayerMutationEvent.Mutation.SPONTANEOUS_COMBUSTION) {
event.setCancelled(true);
event.getTargetEntity().sendMessage(Text.of("You can not combust here, this is a non-smoking area!"));
}
}