BufferObservable.java

        Observable.just("A", "B", "C", "D", "E", "F")
                .buffer(2)
                .subscribe(new Observer<List<String>>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(List<String> strings) {
                        System.out.println("onNext(): ");
                        for (String s : strings) {
                            System.out.println("String: " + s);
                        }
                    }

                    @Override
                    public void onError(Throwable e) {

                    }

                    @Override
                    public void onComplete() {

                    }
                });