RxBus singleton

RxBus.java

public class RxBus {
    private static RxBus instance = null;
    private final Subject<Object, Object> _bus = new SerializedSubject<>(PublishSubject.create());

    private static RxBus getInstance() {
        if (instance == null) {
            instance = new RxBus();
        }
        return instance;
    }

    public static void broadCast(BaseEvent baseEvent) {
        getInstance().send(baseEvent);
    }

    public static void subscribe(final Action1 onNext) {
        getInstance().toObserverable().subscribe(onNext);
    }

    private void send(BaseEvent baseEvent) {
        _bus.onNext(baseEvent);
    }

    private Observable<Object> toObserverable() {
        return _bus;
    }
}