Observable.fromCallable() does not Return data from Arraylist in Android using RXJava

Question

I am trying to use RXjava to get data from an Arraylist in Android

public ArrayList<String> SelecIDValueGetterObservable(Context mContext) {
        ArrayList<String> SelectedIds = new ArrayList<>();
        CompositeDisposable mCompositeDisposable = new CompositeDisposable();
        mCompositeDisposable.add(Observable.fromCallable(() -> SelecetIDValuegetter(mContext))
                .subscribeOn(Schedulers.io())
               // .observeOn(AndroidSchedulers.mainThread())
                .subscribeWith(new DisposableObserver<ArrayList<String>>() {
                    @Override
                    public void onNext(ArrayList<String> IdObsList) {
                        Toast.makeText(mContext,
                                "size " + IdObsList.size(), Toast.LENGTH_LONG).show();
                        
                            for (int i = 0; i < IdObsList.size(); i++) {
                                SelectedIds.add(IdObsList.get(i));
                            }
                      
                    }

                    @Override
                    public void onError(Throwable e) {
                        FirebaseCrashlytics.getInstance().recordException(e);
                    }

                    @Override
                    public void onComplete() {
                        // mCompositeDisposable.dispose();
                    }
                })
        );
        return SelectedIds;
    }

the SelecetIDValuegetter(mContext) is Like this

    public ArrayList<String> SelecetIDValuegetter(Context mContext) {
            ArrayList<String> SelectedIds = new ArrayList<>();
             SelectedIds .add("A");
             SelectedIds .add("B");
             SelectedIds .add("C");
            SelectedIds .add("D");
            return SelectedIds ;
        }

If SelecetIDValuegetter emits data normally, hwoever It deosnot work In Rxjava, how can we do it

Rajan Kali · Accepted Answer · 2021-01-27 07:31:29Z

1

If you want to use Observable, you should not return list directly as Observable is async, instead return Observable and subscribe to receive the data

public Observable<List<String>> SelecIDValueGetterObservable(Context mContext) {
    return Observable.fromCallable(() -> SelecetIDValuegetter(mContext));     
}
//at receiver end
SelecIDValueGetterObservable(this)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(IdObsList -> {
                    //ypu will get the list here
            });

On a side note, Not sure about your need for using Observable in between SelecetIDValuegetter, you can directly return the list instead of using an Observable as you are not doing heavy work in method SelecetIDValuegetter AFAIK.

edited Jan 27, 2021 at 7:31

answered Jan 27, 2021 at 7:21

Rajan Kali

13.1k3 gold badges27 silver badges37 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

1234567 Over a year ago

can you explain the .subscribe( part a bit,I am new to Rxjava Trying to learn about it.how do we use it with CompositeDisposable?

Collectives™ on Stack Overflow

Observable.fromCallable() does not Return data from Arraylist in Android using RXJava

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related