java - RxJava2、Retrofit - doOnNext、doAfterNext、doOnComplete 不调用

Question

我尝试从服务器获取一些数据。

Observable<List<Countries>> backendObservable = mCountriesApi.getCountries()
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread());

backendObservable.doOnNext(list -> Log.d(TAG, "doOnNext"));
backendObservable.doAfterNext(list -> Log.d(TAG, "doAfterNext"));
backendObservable.doOnComplete(() -> Log.d(TAG, "doOnComplete"));

backendObservable.subscribe(new Observer<List<Country>>() {
        @Override
        public void onSubscribe(Disposable d) {

        }

        @Override
        public void onNext(List<Country> value) {
            Log.d(TAG, "doOnNext"));
        }

        @Override
        public void onError(Throwable e) {

        }

        @Override
        public void onComplete() {

        }
    });

它有效，我将数据接收到“onNext”中。但 doOnNext、doAfterNext、doOnComplete 方法不会调用。我做错了什么？

Answer 1

直到 observeOn 之前你都知道了，发生了什么？您必须在 Observable 上链接运算符，因为它们是不可变的数据流计划:

backendObservable = backendObservable.doOnNext(list -> Log.d(TAG, "doOnNext"));
backendObservable = backendObservable.doAfterNext(list -> Log.d(TAG, "doAfterNext"));
backendObservable = backendObservable.doOnComplete(() -> Log.d(TAG, "doOnComplete"));

或者更简洁

Observable<List<Countries>> backendObservable = mCountriesApi.getCountries()
        .subscribeOn(Schedulers.newThread())
        .observeOn(AndroidSchedulers.mainThread())
        .doOnNext(list -> Log.d(TAG, "doOnNext"));
        .doAfterNext(list -> Log.d(TAG, "doAfterNext"));
        .doOnComplete(() -> Log.d(TAG, "doOnComplete"));
        .subscribe(...);