Manually trigger a RxJava combinelatest flowable

Question

So i have a scenario in which i want to combine the newest results of two flowables and do something with it.

Flowable.combineLatest(
                info,
                list,
                BiFunction  {  ... }
        )

In certain conditions, i need to be able to get the the results again, and do some different stuff from before. So i could manually store the results of combinelatest somewhere, and then just reuse them but i was thinking, maybe there is a way to add a third flowable, and trigger onNext manually so the results are propagated again. Is this possible?

Answer 1

There are two approaches to keeping the computed value around for later use. You can create a BehaviorSubject that acts as an intermediate variable, that when defined will have the computed value, or you can publish() the observable so that newer subscribers will get the most recent results.

BehaviorSubject intermediateResult = BehaviorSubject.create();

Flowable.combineLatest(info, list, ...)
  .subscribe( intermediateResult );

Alternatively,

Observable<Type> intermediateResult = Flowable.combineLatest(info, list, ...)
  .replay(1)
  .publish();

In either case, subscribing to intermediateResult will get the most recent computed value, if it is present.

Edit: make the function selectable on the fly:

Observable<FunctionSelector> fnSelector;

Observable<Type> intermediateResult = 
  Flowable.combineLatest(info, list, fnSelector, 
     (information, listToUse, selector) -> 
       getFunction(selector).apply(information, listToUse))
  .replay(1)
  .publish(1);