some.java

Observable<Integer> oi = Observable.create(new OnSubscribe<Integer>() {
    @Override
    public void call(Subscriber<? super Integer> subscriber) {
        // we now receive a Subscriber instead of Observer
        for (int i = 1; i < 1000000; i++) {
            // the OnSubscribe can now check for isUnsubscribed
            if (subscriber.isUnsubscribed()) {
                return;
            }
            subscriber.onNext(i);
        }
        subscriber.onCompleted();
    }

});

I've only gotten this far:

        return Observable.create(Observable.OnSubscribe<JSONObject> {
            val response: Response = this.postJson(url, json)
            if (!response.isSuccessful()) {

            }
        })