RxJava: observeOn, subscribeOn, and doFinally, switching between IO and UI thread

Question

I am running into an issue where my observable is subscribed on an IO thread and observed on the android main (UI) thread but the `doFinally` operator is run on the IO thread and it needs to be run on the UI thread. The usecase is almost exactly the same as this medium article. I essentially want to show a `ProgressBar` when the Observable is subscribed to and hide the `ProgressBar` when the Observable is terminated or finished. The error I am getting is: java.lang.IllegalStateException: The current thread must have a looper! Can anyone help me move the `doFinally` action back to the UI thread which has a looper? Or am I missing some other piece of information? EDIT The usecase workflow is: -> Launch Activity -> initialize -> execute observable stream -> Start new Activity and finish current activity -> New activity -> Start original activity and finish -> repeat initialize Thank you very much. Details: - RxJava 2.0.7 - RxAndroid 2.0.1 - Android sdk min 14 and target 25 Example Code `…

Accepted Answer

The issue was occurring because I was not disposing the subscription when an activity was finished/destroyed. Now each activity/view tells the presenter when they are stopped or destroyed and the presenter disposes of the subscription. This appears to have solved my issue. ``` @Override public void initialize() { if (!isViewAttached()) { throw new ViewNotAttachedException(); } disposable = listUseCase.execute(null) .subscribeOn(schedulerProvider.io()) // Move subscribe on here .observeOn(schedulerProvider.main()) // Change threads here .doOnSubscribe(new Consumer() { @Override public void accept(@NonNull Disposable disposable) throws Exception { getView().showLoading(true); // This should be on the main thread also } }) .doFinally(new Action() { @Override public void run() throws Exception { getView().showLoading(false); } }) .subscribe( new Consumer>() { @Override public void accept(@NonNull List accountEntities) throws Exception { getView().setAccounts(accountEntities); } }, new Consumer() { @Override public void accept(@NonNull Throwable throwable) throws Exception { if (isViewAttached()) { getView().showError(throwable.getMessage()); } } } ); } @Override public void dispose() { if (disposable != null) { disposable.dispose(); } } ```

RxJava: observeOn, subscribeOn, and doFinally, switching between IO and UI thread

Solution

Problem