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Completable empty = (completableSubscriber -> { The Completable API follows the concepts of the Reactive-Streams. Create, Lift and Transform. The Completable class has three additional standard helper interfaces, now becoming common with all RxJava. Creating a Single. Completable. Creating a Completable. Maybe. Creating a Maybe. RxCocoa traits. Driver. Why is it named Driver; Practical usage example.

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It is the object which makes the whole magic of reactive programming possible. Why would you need anything else, right?

Have you considered whether you actually need to know about those 3 events every time? The documentation over at ReactiveX goes on about continuous crreate of events so much that we often forget we usually only care about observing just one event that happened or just observing that something completed or failed.

One of the most common use cases for RxJava in Android is for doing network calls. This is perfectly fine and you cdeate use it as is. The code that uses it can take a form like this:.


So our API client now looks like this:. Now, our above use case can be simplified to this:. Oh, and if for some reason you have an Observable that you know for sure behaves xreate a Single, you can convert it using the singleOrError operator.

We want to change some properties on the MyData object and then send it to the server to update in its database. What most server API design does in this case is just respond with the updated object when successful. So your client code would be:.

java – How to create Observable out of Runnable? – Stack Overflow

In this case do we even need the MyData result, though? What we want is to just be notified that the update succeeded. Meaning, we just want the onComplete event. Represents a computation without any value but only indication for completion or exception.

By using Completable we agree to ignore the onNext event and only handle onComplete and onError.

RxJava: Single, Maybe and Completable – AndroidPub

The API client then becomes:. Completables by their nature are quite different from Observable and Single due to not emitting items.


Therefore you end up using a different set of operators if you want to chain actions. The most versatile one being andThen.

Clearer RxJava intentions with Single and Completable

Unlike Single RxJava does not allow an Observable to be converted to a Completable directly, because there is no way to know that an Observable will ever complete. You can convert a Single to a Completable, though, since a Single guarantees that onComplete will get called.

The operator to use in that case is toCompletable. Through this brief and simple introduction to Single and Completable hopefully you can see that these two constructs can help in the goal of clearer code.

They better explain to the user what to expect.

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