RxBus.java

import rx.Subscription;
import rx.android.schedulers.AndroidSchedulers;
import rx.subjects.PublishSubject;
import rx.functions.Action1;

public class RxBus {

    public enum Key {
        VAL_1, VAL_2
    }
    
    private final PublishSubject<Key> bus;

    public RxBus() {
        bus = PublishSubject.create();
    }

    public void publish(Key... keys) {
        for (Key key : keys) {
            bus.onNext(key);
        }
    }

    public Subscription subscribe(final Key key, Action1<Key> onNext) {
        return bus
                .filter({ k -> k == key })
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(onNext);
    }
}