RxAndroid - run two observable in parallel and combine the result

[Mouna Cheikhna]

I have a service where i can ask for an image and some metadata separately : 

 with two observables : Observable<Metadata> and Observable<Image> 

I would like to run both in parallel and combine them so i can use observeOn(AndroidSchedulers.mainThread()); and use their results and display the image with its data.

I've tried multiple operators but most of them require observables of the same type, any pointers on how to do this ? 

Thanks.

[Samuel Tardieu]

Did you by chance miss the zip() family of operators?

  Sam

[Matteo Landi]

You could go with Observable.combineLatest() and for example make the aggregator function a tuple of metadata and image. --Matteo

[Mouna Cheikhna]

combineLatest seemed to be a viable solution only problem is that it may associate a bitmap with another metadata if a loading of a bitmap from Observable<Bitmap> happens before it's predecessor, 

is there a way to restrict combination on a common key or something like that ? 

Thanks

[Shixiong Zhu]

Why not try `zip`?

Best Regards,

Shixiong Zhu

[Arild Jacobsen]

Sorry to be hammering this point, but I was mid-post when Shixiong Zhu posted. As both Shu and Samuel mentioned, zip definitely seems to be the correct operator for combining two observables in matched pairs. 

e.g.

    Observable.zip(imageObservable, metaDataObservable, new Func2<Image, Metadata, TupleOrSomething>() {

        @Override

        public TupleOrSomething call(Image img, Metadata meta) {

                return new TupleOrSomething(img, meta);

            }

        }).subscribe(new Subscriber<TupleOrSomething>() {...});

[Mouna Cheikhna]

I ended up using zip and it worked out pretty well. Thanks everyone