Khuzy Khuzy - 6 months ago 27
Android Question

RxJava explain this loop

can someone explain me this loop?

private Observable<ArrayList<RateItem>> generateRates(List<Rates> rates){
rateItemArrayList = new ArrayList<RateItem>();

Observable<ArrayList<RateItem>> observable = Observable.from(rates)
.map(new Func1<Rates, ArrayList<RateItem>>() {
public ArrayList<RateItem> call(Rates r) {
for(Rates rat : rates)
rateItemArrayList.add(new RateItem(rat.getName(),rat.getCode(),rat.getValue()));
return rateItemArrayList;
return observable;

My List has 35(checked) items after response from server, then i want to make different ArrayList from this list. Why this loop iterate about 1000 times instead of 35? After that my new ArrayList has 1350 items o.O.


you code contains a side effect : a method update a object outside of his context (here, the map method update a list outside of it).

Then your for loop is quite strange as you loop over rates variables, which is used to build the Observable too. (Which I think is not expected)

Your code can be simplier, using non side effect code :

 private Observable<List<RateItem>> generateRates(List<Rates> rates){
      return Observable.from(rates)
                       .map(r -> new RateItem(r.getName(), r.getValue())

it should be quite close to what you want to achieve.