AllObservable.java

        Observable.just(0, 1, 2, 3, 4, 0, 6, 0)
                .all(item -> item > 0)
                .subscribe(new SingleObserver<Boolean>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onSuccess(Boolean aBoolean) {
                        System.out.println("onNext: " + aBoolean);
                    }

                    @Override
                    public void onError(Throwable e) {

                    }
                });