Handler Lists

Every Event that can be listened to has a HandlerList containing all the listeners that are listening to that event. This list is used to call the listeners when the event is called.

Getting the handler list for an event

To get the handler list for an event, you can call getHandlerList() on the specific event class.

ExampleListener.java

public class ExampleListener implements Listener {

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent event) {
        HandlerList handlerList = event.getHandlerList();
        // ...
    }
    
    // Or:
    
    public ExampleListener() {
        // Access the handler list through the static getter
        HandlerList handlerList = PlayerJoinEvent.getHandlerList();
        // ...
    }
}

Unregistering a listener

To unregister a listener, you can call unregister() on the HandlerList that the listener is registered to.

ExampleListener.java

public class ExampleListener implements Listener {

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent event) {
        HandlerList handlerList = event.getHandlerList();
        handlerList.unregister(this);
        // ...
    }
    
    // Or:
    
    public ExampleListener() {
        // Access the handler list through the static getter
        HandlerList handlerList = PlayerJoinEvent.getHandlerList();
        handlerList.unregister(this);
        // Granted this is a pretty stupid example...
    }
}

You can unregister based on Listener or Plugin for more convenience. Likewise, you can also unregister all listeners for a specific event by calling unregisterAll() on the HandlerList.