RxJava无法在未调用Looper.prepare（）的线程内创建处理程序

Question

Okay, so I am having a bit of trouble with an RxJava Observable I am using in my Android app. It is extremely frustrating because this has been working for a while now and is only now throwing the error above. I am aware that this means I am doing a UI operation from another thread but I do not see where that is happening. So here is the observable:

 ConnectionsList.getInstance(this).getConnectionsFromParse(mCurrentUser)
            .delay(3, TimeUnit.SECONDS)
            .flatMap(s -> mainData.getDataFromNetwork(this, mCurrentUser, mSimpleFacebook))
            .flatMap(s -> mainData.getPictureFromUrl(s))
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Observer<Bitmap>() {
                @Override
                public void onCompleted() {
                    if (mCurrentUser.get(Constants.NAME) != null) {
                        mNavNameField.setText((String) mCurrentUser.get(Constants.NAME));
                    }
                    mSearchFragment.setupActivity();
                }

                @Override
                public void onError(Throwable e) {
                    e.printStackTrace();
                    mSearchFragment.setEmptyView();
                }

                @Override
                public void onNext(Bitmap bitmap) {
                    mNavProfImageField.setImageBitmap(bitmap);
                    mainData.saveImageToParse(bitmap); //save the image to Parse backend
                }
            });

After some debugging I found that this flatmap is where the error is happening:

.flatMap(s -> mainData.getDataFromNetwork(this, mCurrentUser, mSimpleFacebook))

Inside of that is the following, I have added a comment where the error is being thrown:

 return Observable.create(subscriber -> {
            //set the username field if ParseUser is not null
            if(currentUser != null) {
                username = (String) currentUser.get(Constants.NAME);
            }

            //if prof pic is null then request from facebook. Should only be on the first login
            if (currentUser != null && currentUser.getParseFile(Constants.PROFILE_IMAGE) == null) {
                if (AccessToken.getCurrentAccessToken() != null) { //check if session opened properly
                    //get simple facebook and add the user properties we are looking to retrieve
                    Profile.Properties properties = new Profile.Properties.Builder()
                            .add(Profile.Properties.FIRST_NAME)
                            .add(Profile.Properties.GENDER)
                            .add(Profile.Properties.BIRTHDAY)
                            .add(Profile.Properties.ID)
                            .add(Profile.Properties.EMAIL)
                            .build();

                    //The following line is where the debugger stops 
                    //and the error gets thrown
                    simpleFacebook.getProfile(properties, new OnProfileListener() {
                        @Override
                        public void onComplete(Profile response) {
                            String id = response.getId();
                            String name = response.getFirstName();
                            String gender = response.getGender();
                            String birthday = response.getBirthday();
                            String email = response.getEmail();
                            String age = getAge(birthday);

                            currentUser.put(Constants.NAME, name);
                            currentUser.put(Constants.AGE, age);
                            currentUser.put(Constants.GENDER, gender);
                            currentUser.put(Constants.EMAIL, email);
                            currentUser.saveInBackground();

                            if (id != null) { //display the profile image from facebook
                                subscriber.onNext("https://graph.facebook.com/" + id + "/picture?type=large");
                            }
                        }

Whats going on here? Its been working fine as is and now it is saying that I am on some helper thread. As far as I was concerned I was on the UI thread up to this point. If someone can help me that would be great, otherwise I may have to drop RxJava for the time being as it is not working out for me. Thanks in advance!

Answer 1

It looks like the simpleFacebook.getProfile(properties, listener) call does it's own threading internally. Typically you don't want this with rxjava. You want rxjava to take care of the threading and all code you write should be synchronous.

I am not familiar with the Facebook SDK, but I would look for a call that executes the request synchronously. So a method that looks like public Profile getProfile(Properties properties) { instead of one returning void and requiring a listener.

Hope this helps..