how do you approach updating the view model during long running tasks? I have to crawl data from ~20 websites and display it as a list. Do I: • make an

update publisher

(new items are being pushed into it) • refresh the view model data every let's say 1s • try to implement it so that if the user get's to the end of the list, more items are loaded

I'd say that if it takes much time it means it is not the best approach to display it on screen. You'll have to rethink your screen. Maybe make a viewpager and display each data retrieved from each site on a single page... Otherwise, if you really want to do what you said, I suggest you use PagedList and update your item's list with LiveData each time an item is available

Sounds like a job for

MediatorLiveData

. Suppose you have 10 websites to crawl.

data class Website(val url: String)

val sitesToCrawl: List<Website> = TODO()

fun crawl(url: String): LiveData<List<PageData>> = TODO()

val observer = MediatorLiveData<List<PageData>>().apply { value = list() }

sitesToCrawl.forEach { site ->
  val ld = crawl(site.url)
  observer.addSource(ld) { list ->
    observer.value = observer.value+list
  }
}

Something like that. Can’t remember if I’m doing list concat correctly.

@atlantis210 it's doesn't take a lot of time to load, it's just I'm new to android and I don't know how to solve the problem, currently I use the first approach these tasks are long running but they are not blocking the main thread @forward many thanks for the tip, I didn't know about this class, will make use of it