Event Bus implementation with RxJava. It also post all event in the UI Thread.

RxEventBus.java

import android.os.Handler;
import android.os.Looper;

import com.google.inject.Inject;
import com.google.inject.Singleton;

import rx.Subscription;
import rx.functions.Action1;
import rx.functions.Func1;
import rx.internal.util.SubscriptionList;
import rx.subjects.PublishSubject;
import rx.subjects.SerializedSubject;
import rx.subjects.Subject;

/**
 * Created by nicolas on 7/21/16.
 */
//@Singleton
public class RxEventBus {
    
    private static RxEventBus instance;
    private final Subject<Object, Object> eventBus = new SerializedSubject<>(PublishSubject.create());
    private SubscriptionList subscriptionList;
    private final Handler mainThread = new Handler(Looper.getMainLooper());

    //@Inject
    private RxEventBus() {
        subscriptionList = new SubscriptionList();
    }
    
    public static RxEventBus getInstance() {
        if(instance == null) {
            instance = new RxEventBus();
        }
        return instance;
    }

    public void post(final Object event) {
        if(Looper.myLooper() == Looper.getMainLooper()) {
            eventBus.onNext(event);
        }else {
            mainThread.post(new Runnable() {
                @Override
                public void run() {
                    eventBus.onNext(event);
                }
            });
        }

    }

    public <T> Subscription register(final Class<T> eventClass, final Action1<T> onNext) {

        Subscription subs = eventBus.filter(new Func1<Object, Boolean>() {

            @Override
            public Boolean call(Object event) {
                return event.getClass().equals(eventClass);
            }
        }).map(new Func1<Object, T>() {
            @Override
            public T call(Object object) {
                return (T) object;
            }

        }).subscribe(onNext);

        subscriptionList.add(subs);

        return subs;
    }

    public void unregister(Subscription subscription) {
        subscriptionList.remove(subscription);

    }

    public void unregisterAll() {
        subscriptionList.unsubscribe();
    }


}