2.x: IllegalStateException: Disposable already set!

[amitshekhariitbhu]

The below code gives the exception - (IllegalStateException: Disposable already set!):

Single.just("Amit")
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new SingleObserver<String>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                    }

                    @Override
                    public void onSuccess(String value) {
                    }

                    @Override
                    public void onError(Throwable e) {
                    }
                });

But when I remove subscribeOn and observeOn like below it works :

Single.just("Amit")
                .subscribe(new SingleObserver<String>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                    }

                    @Override
                    public void onSuccess(String value) {
                    }

                    @Override
                    public void onError(Throwable e) {
                    }
                });

[akarnokd]

Thanks for the feedback, there is a state management bugin Single.subscribeOn that causes this. I'll post a PR to fix this today; once merged, you may want to switch to the RxJava 2 snapshots to get this fix and dozen others since RC1.

[akarnokd]

Fixed in #4450.

[bitsydarel]

Still getting the same error io.reactivex.exceptions.ProtocolViolationException: Disposable already set!

subscriptions.add(mWeatherObservableWithNetwork
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribeWith(mWeatherObserver));

when i remove the subscribeOn and ObserveOn, No exception

Using rxjava 2.0.6

[akarnokd]

@bitsydarel Hi and thanks for using RxJava. In order to help you, could you clarify the following:

• What is the type of mWeatherObservableWithNetwork?
• Did you make sure the RxAndroid 2 doesn't force your project to use RxJava 2.0.1?
• Could you provide the full stacktrace of the ProtocolViolationException? It may provide the hints where exactly the unwanted call happens from within RxJava.

[bitsydarel]

@akarnokd
mWeatherObservableWithNetwork = Single

from the github of RxAndroid they suggest to use 2.0.6 :
RxAndroid 2.0.1:
RxJava 2.0.6:

StackTrace :
02-28 18:51:12.241 19971-19971/com.darelbitsy.dbweather E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.darelbitsy.dbweather, PID: 19971
io.reactivex.exceptions.ProtocolViolationException: Disposable already set!
at io.reactivex.internal.disposables.DisposableHelper.reportDisposableSet(DisposableHelper.java:156)
at io.reactivex.internal.disposables.DisposableHelper.setOnce(DisposableHelper.java:82)
at io.reactivex.observers.DisposableSingleObserver.onSubscribe(DisposableSingleObserver.java:32)
at io.reactivex.internal.operators.single.SingleObserveOn$ObserveOnSingleObserver.onSubscribe(SingleObserveOn.java:57)
at io.reactivex.internal.operators.single.SingleSubscribeOn.subscribeActual(SingleSubscribeOn.java:35)
at io.reactivex.Single.subscribe(Single.java:2692)
at io.reactivex.internal.operators.single.SingleObserveOn.subscribeActual(SingleObserveOn.java:35)
at io.reactivex.Single.subscribe(Single.java:2692)
at io.reactivex.Single.subscribeWith(Single.java:2736)
at com.darelbitsy.dbweather.ui.CurrentWeatherFragment.lambda$-com_darelbitsy_dbweather_ui_CurrentWeatherFragment_lambda$1(CurrentWeatherFragment.java:257)
at com.darelbitsy.dbweather.ui.-$Lambda$0.$m$0(Unknown Source)
at com.darelbitsy.dbweather.ui.-$Lambda$0.onRefresh(Unknown Source)
at android.support.v4.widget.SwipeRefreshLayout$1.onAnimationEnd(SwipeRefreshLayout.java:189)
at android.support.v4.widget.CircleImageView.onAnimationEnd(CircleImageView.java:105)
at android.view.ViewGroup.finishAnimatingView(ViewGroup.java:6270)
at android.view.View.draw(View.java:16371)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at android.view.View.draw(View.java:16446)
at android.view.View.updateDisplayListIfDirty(View.java:15387)
at android.view.View.draw(View.java:16188)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at android.view.View.draw(View.java:16446)
at android.view.View.updateDisplayListIfDirty(View.java:15387)
at android.view.View.draw(View.java:16188)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at android.view.View.draw(View.java:16446)
at android.support.v4.view.ViewPager.draw(ViewPager.java:2443)
at android.view.View.updateDisplayListIfDirty(View.java:15387)
at android.view.View.draw(View.java:16188)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at android.view.View.updateDisplayListIfDirty(View.java:15379)
at android.view.View.draw(View.java:16188)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at android.view.View.updateDisplayListIfDirty(View.java:15379)
at android.view.View.draw(View.java:16188)
at android.view.ViewGroup.drawChild(ViewGroup.java:3735)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3525)
at com.android.internal.policy.PhoneWindow$DecorView.dispatchDraw(PhoneWindow.java:2751)
at android.view.View.draw(View.java:16446)
at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2737)
at android.view.View.updateDisplayListIfDirty(View.java:15387)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:286)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:292)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:327)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:3060)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2864)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2476)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1366)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6758)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:896)
at android.view.Choreographer.doCallbacks(Choreographer.java:698)
at android.view.Choreographer.doFrame(Choreographer.java:633)
at android.view.Choreographer$FrameDisplayEventRe

[akarnokd]

Based on the stacktrace of io.reactivex.observers.DisposableSingleObserver.onSubscribe(DisposableSingleObserver.java:32) it seems you are reusing a DisposableSingleObserver, otherwise the failure would have been issued by Single.observeOn by itself. If not, please provide an example of your flow.

[bitsydarel]

That was it, thanks for the help too and for the work, really helping!

there was no mention of this behavior in the documentation right?

[akarnokd]

It was not mentioned explicitly anywhere. I've created #5148 to track the progress on updating the documentation.

[xiaogu-space]

but I also met it like this

[akarnokd]

The provided XObservers and XSubscribers are not reusable; you have to create a fresh one when subscribing to a source.

[xiaogu-space]

@akarnokd thanks

[akarnokd]

The PR #5210 adds documentation about these.