How to unsubscribe from Flowable in RxKotlin/RxJava?

Question

I am using Room with RxJava/RxKotlin Flowable following this article. I got it running but the got issue using it with ViewPager with 3 fragments.

I will walk you through my code little bit:

I have a viewpager with tab layout and three fragments(A, B, and favorites). First two fragments contain lists of data which can be added to favorite.

In favorite fragment, I am using Flowable to listen to changes made by A and B and update list accordingly. But what happens is when an item is made favorite in A and B, app crashes because the Flowable subscription in favorite fragment runs even when the fragment is not in foreground.

What I want is to be able to stop the subscription when the fragment is not in foreground and start in foreground.

I tried to stop it in onPause method of favorite fragment but flowable has no unsubscribe or dispose method.

My code is

dbRepository?.getAllImportant()?.subscribeOn(Schedulers.io())
            ?.observeOn(AndroidSchedulers.mainThread())
            ?.subscribe(getFlowableSubscriber())

The lambda-`subscribe` will get you a `Disposable` back. Keep it around and dispose it in `onPause` for example. — akarnokd, Aug 03 '18 at 10:00
@akarnokd check my code above, this is returning a Unit data type in Kotlin — hasn, Aug 03 '18 at 10:39

score 3 · Answer 1 · answered Sep 11 '18 at 10:27

You should include the Flowable in a compositeDisposable(), and use composite.dipose() when you want unsubscribe.

CompositeDisposable composite = new CompositeDisposable();

composite.add(dbRepository?.getAllImportant()?.subscribeOn(Schedulers.io())
        ?.observeOn(AndroidSchedulers.mainThread())
        ?.subscribe(getFlowableSubscriber())

and then when you want unsubscribe:

composite.dispose();

Normally you should unsubscribed the Flowable in the onDestroy or onPause method.

hasn · Accepted Answer · 2018-09-11T10:34:55.007

Thank you for answers. I found a work around. By saving Subscription in onSubscribe(subscription: Subscription) function of FlowableSubscriber. And later calling subscription.cancel in onStop()

        override fun onSubscribe(subscription: Subscription) {
            log("onSubscribe")
            this@ImportantFragment.subscription = subscription
        }

And

    override fun onStop() {
           log("onStop() ")
           this.subscription.cancel()
           super.onStop()
     }

score 0 · Answer 3 · answered Aug 03 '18 at 10:06

0

When you subscribe to a Flowable it returns a Dispose object. If you call dispose() on that, you will unsubscribe from the disposable.

I can't see your code, but if that object is not accessible to you, you can also add a takeUntil or takeWhile to your Flowable if you are out of view. This is a bit of a hack though because it doesn't unsubscribe from the source observable until the next item is emitted and takeUntil is called. Calling dispose is the best option.

answered Aug 03 '18 at 10:06

Alex

2,953
1
27
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Thank you for answer. I have added a snippet of my code above. I am using Kotlin and this code returns Unit data type not Dispose. – hasn Aug 03 '18 at 10:38

score 0 · Answer 4 · answered Jun 17 '21 at 14:10

0

For the current situation: let your subscriber extend DisposableSubscriber, and subscribe like


yourFlowable
  .subscribeWith(yourSubscriber)
  .addTo(compositeDisposable)

answered Jun 17 '21 at 14:10

Jule

871
5
13

How to unsubscribe from Flowable in RxKotlin/RxJava?

4 Answers4