如何使用RxJava避免回调地狱

Question

subscriptionSet = provider.removeGeofences(mGeofencePendingIntent).observeOn(AndroidSchedulers.mainThread()).subscribe(new Subscriber<Status>() {
            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {
                Log.d(TAG, "onError() called with: " + "e = [" + e + "]");
            }

            @Override
            public void onNext(Status status) {
                Prefs.geofence.clear();
                subscriptionAdd = statusObservable.observeOn(AndroidSchedulers.mainThread()).subscribe(new Subscriber<Status>() {
                    @Override
                    public void onCompleted() {

                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError() called with: " + "e = [" + e + "]");
                    }

                    @Override
                    public void onNext(Status status) {
                        Prefs.geofence.set(...);
                    }
                });
            }
        });

我正在尝试使用优秀的Android-ReactiveLocation库来实现类似于集合操作的地理围栏 - 如果已存在，则清除它并将其设置为所需位置，以便始终只有一个地理围栏。

同时，我也在学习RxJava，听说它可以解决回调地狱问题，那么在我的情况下它如何解决呢？

谢谢！

- Ofek Ron

Answer 1

当您想要使用连续的订阅时，应使用flatMap操作符。这样，您的问题可以简化为：

subscription = provider.removeGeofences(mGeofencePendingIntent)
            .flatMap(new Func1<Status, Observable<Status>>() {
                @Override
                public Observable<Status> call(Status status) {
                    //after the first subscription
                    Prefs.geofence.clear();
                    return statusObservable;
                }
            })
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Action1<Status>() {
                @Override
                public void call(Status status) {
                    //after the second subscription
                    Prefs.geofence.set(...);
                }
            }, new Action1<Throwable>() {
                @Override
                public void call(Throwable throwable) {
                    Log.d(TAG, "onError() called with: " + "e = [" + e + "]");
                }
            });

- Bartek Lipinski