How to convert rxJava2's Observable to Completable?

问题

I have Observable stream, and I want to convert it to Completable, how I could do that?

回答1:

The fluent way is to use Observable.ignoreElements().

Observable.just(1, 2, 3)
.ignoreElements()

Convert it back via toObservable if needed.

回答2:

You can do something like below.

Observable<Integer> observable = Observable.just(1, 2, 3);
Completable completable = Completable.fromObservable(observable);

Like on an Observable, you will have to subscribe to the completable to start the asynchronous process that Observable wraps.

More details can be found here in the Java doc for the method.

回答3:

As I understand all this solutions will work only if Observable call onComplete, which is not enough if you want your result Completable to trigger after first onNext or onError, so for this case I'd recommend this:

Observable<Integer> observable = Observable.just(1, 2, 3);
Completable completable = observable.firstOrError().ignoreElement()

回答4:

Use Completable.merge(YourObservable()...

回答5:

You could use Completable.fromObservable(xx). That is worked fine on my project.

来源：https://stackoverflow.com/questions/40399397/how-to-convert-rxjava2s-observable-to-completable