java - Automatically get items from observable when an event is fired without an eventbus -

what best way automatically retrieve new items observable when have external event tells you should?

for example , lets have , itemrepository implements getallitems() method (which returns observable<list<item>> webservice) , , then, external event (like push notification) tells application data needs refreshed. (also itemrepository used in presenter , presenter has called getallitems , on it's onnext, it's data s refreshed.)

i know can done event bus (listen event , when fired, fetch again) , i'm wondering if it's possible automatically.

thanks.

edit

this solution came , of sqlbrite library , not sure if best or cleanest way it. have publishsubject events sent to:

publishsubject<object> updateevent;

and in getallitems() method , check events subject:

public observable<list<item>> getall() {     observable.onsubscribe<list<item>> subscribe = subscriber -> {         updateevent.subscribe(s -> {             subscriber.onnext(dbitemrepository.getall());         });         subscriber.onnext(dbitemrepository.getall());// first call     };     final observable<list<item>> automatonobservable = observable.create(subscribe) =             .onbackpressurelatest()             .observeon(schedulers.computation())             .onbackpressurelatest();     return automatonobservable; } 

i think rodrigo henriques has right idea, need change bit according question:

public static observable<string> observerepositoryupdates(itemsrepository repo, observable<void> updatetrigger) {   updatetrigger     //you can insert observeon here     .flatmap(event -> repository.getallitems()); }  public static void dowork() {   itemsrepository repo = new itemsrepository();   publishsubject<void> updatetrigger = publishsubject.create();    observerepositoryupdates(repo, updatetrigger)     .subscribe(items -> system.out.println(items.tostring());    updatetrigger.onnext(null);//trigger update } 

depending on event, doesn't have publishsubject, other observable can trigger repository update.

if event happens , want drop running repository update , start new one, can use operator switchmap.