RxJava - zip list of Observable

Question

I have a list of Observables (RxJava 1).

List<Observable> observableList = new ArrayList<>();

It can contain at least 1 Observable. Each has the same type of the result.

How can I zip results of the all Observables?

I thought about zip-operator but it doesn't support List and I don't know quantity of observables (it can be 1,2,3,4....)

Answer 1

You can use the static zip(java.lang.Iterable<? extends Observable<?>> ws,FuncN<? extends R> zipFunction) method.

It is a zip method that takes an Iterable of Observables and a FuncN (which takes a varargs parameter for its call method) and uses it to combine the corresponding emitted Objects into the result to be omitted by the new returned Observable.

So for example you could do:

Observable.zip(observableList, new FuncN(){
    public ReturnType call(java.lang.Object... args){
        ReturnType result; //to be made
        //preparatory code for using the args
        for (Object obj : args){
            ReturnType retObj = (ReturnType)obj;
            //code to use the arg once at a time to combine N of them into one.
        }
        return result;
    }
});