Combine a list of Observables and wait until all completed

Question

TL;DR How to convert Task.whenAll(List) into RxJava?

My existing code uses Bolts to build up a list of asynchr

Answer 1

You can use flatMap in case you have dynamic tasks composition. Something like this:

public Observable whenAll(List> tasks) {
    return Observable.from(tasks)
            //execute in parallel
            .flatMap(task -> task.observeOn(Schedulers.computation()))
            //wait, until all task are executed
            //be aware, all your observable should emit onComplemete event
            //otherwise you will wait forever
            .toList()
            //could implement more intelligent logic. eg. check that everything is successful
            .map(results -> true);
}

Another good example of parallel execution

Note: I do not really know your requirements for error handling. For example what to do if only one task fails. I think you should verify this scenario.