RxJava：动态创建Observables并将最终结果作为Observable发送

Question

I am using RxJava in which I want to dynamically create a number of Observables based on some condition. Once I'm done with creating, I want to do some processing on the different values returned by the observables and then send as a single Observable to which I can subscribe on. Here is how my code is :

List<String> valueList = .... 

List<Observable<String>> listOfObservables = new ArrayList<Observable<String>>();

for(int i =; i <valueList.size(); i++){
        listOfObservables.add(new SomeClass.doOperation(valueList(i)));
        // SomeClass.doOperation will return an Observable<String>
    }

return Observable.merge(listOfObservables);

But here , I want to do some operation on the values emitted by different Observables in the listOfObservable and finally return it as a single Observable<String>

Like in Observable.zip() , I can do this like

return Observable.zip(observable1, observable2, (string1, string2) -> {
            // joining final string here
            return string1 + string2;

But I know the number of arguments here. Please let me know how I can achieve this.

Answer 1

Use the zip overload that takes a variable number of arguments , it has a signature of

<R> Observable<R> zip(Iterable<? extends Observable<?>> ws,
                      FuncN<? extends R> zipFunction)

Example usage:

List<String> valueList = .... 

return Observable.from(valueList)
    .map(string -> SomeClass.doOperationThatReturnsObservable(string))
    .toList()
    .flatMap(listOfObs -> Observable.zip(listOfObs, (Object[] results) -> {
       // do something with the strings in the array.
       return Arrays.stream(results)
                    .map(Object::toString)
                    .collect(Collectors.joining(","));
    }));