reactive programming - RXJava Android - Observable result needed to create another observable -

i cant find way combine or chain list of observables it´s responses prerequisites other call creates observable.

i´m using retrofit observables.

my service:

string url = "/geocode/json?sensor=false";  @get(url) observable<geocoderesult> getreverse(@query("key") string gmapskey,                                      @query("latlng") latlng origin); 

and service needs geocoderesult

@post("/api/orders") observable<order> createorder(@body geocoderesult neworder); 

1. and i´m trying with:

   // prerequisite 1 observable geocodeobservable = address.get(...);

   // call createorder after geocode obtained? return observable.combinelatest(geocodeobservable, geocode -> createorder(geocode));

but don´t work because combinelatest needs object, not observable need return observable.

with joinobservable:

pattern5<geocode> pattern = joinobservable.from(geocodeobservable) plan0<observable<order>> plan = pattern.then(order::create); return joinobservable.when(plan).toobservable().toblocking().single(); 

but throws nosuchelementexception exception. why?

i toblocking().single() because need observable , not observable<observable<order>> :(.

or how can it?

you try using flatmap can take second observable parameter.

the function takes items emitted first observable , creates observable each of items , flattens items emitted observables single observable. sounds complex, fortunately both retrofit functions emit single item, 1 observable gets "flattened" observable.

you can use flatmap this:

restapi.getreverse(gmapskey, origin)     .flatmap(geocoderesult -> createorder(geocoderesult))     .subscribe(order -> dosomething(order)); 

combinelatest doesn't fit needs, because perform both rest calls @ same time, not 1 after other, can't use response of first 1 parameter of second. can't comment on why exception gets thrown joinobservable because it's not part of public api. toblocking() shouldn't used other testing.