RxJava CountDownTimer RxJava实现倒计时

//倒计时10-1    
Observable.interval(1, TimeUnit.SECONDS)
                .take(10) // up to 10 items
                .map(new Function() {
                    @Override
                    public Long apply(Long v) throws Exception {
                        return 10 - v;
                    }
                })
                .subscribeOn(Schedulers.computation())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Observer() {
                    @Override
                    public void onSubscribe(@NonNull Disposable d) {
                        // on start
                    }

                    @Override
                    public void onNext(@NonNull Long aLong) {
                        Log.i(TAG, "count down : aLong=" + aLong);
                      
                    }

                    @Override
                    public void onError(@NonNull Throwable e) {

                    }

                    @Override
                    public void onComplete() {                     
                        Log.i(TAG, "----------倒计时结束------------");
                    }
                });