CODEWITHSUNDEEP
javaandroidandroid-asynctaskandroid-fragmentsandroid-viewpager
Mridang Agarwalla
Mridang Agarwalla

Reputation: 44978

Long running AsyncTasks for Fragments in a ViewPager

I have an activity powered by a FragmentPagerAdapter which adds fragments as the user swipes left and right.

This child fragment that is added is currently static and contains a ListView of items. I intend to use and AysncTask to get items for the ListView but this process can take as much as 10-15 seconds.

I'm still lost with a few things:

From which method should my AsyncTask be invoked? Would it be the onCreate method of the Fragment? I'd only like the AsyncTask to be invoked when the Fragment is in focus.

The biggest question however is, what happens to my AysncTask when the user swipes away from the screen while the AsyncTask is loading. Is the Activity destroyed? Is there a way I can prevent the Activity from being destroyed? If I don't do this, all the progress made by the AsyncTask is lost and I have to reinvoke the AsyncTask when that Fragment comes into focus.

Thanks.

Reason for slowness:

I'm scraping a page with about a 150 records and jSoup is really, really slow. The problem with not using a service is that the data has a high probability of changing and I don't want to "pre-scrape" the data.

@Fildor suggested using a Loader to do the heavy lifting. A quick look at the Loader implementation showed that allows you persist data across short durations, like orientation change. I'm still wondering whether the ViewPager's swing across Fragments would allow the data to persist in the Loader momentarily.

Upvotes: 1

Views: 1562

Answers (2)

Rajesh Batth
Rajesh Batth

Reputation: 1662

Use FragmentStatePagerAdapter you can simply start asyncTask from onCreateView of fragment

Upvotes: 0

Fildor
Fildor

Reputation: 16094

Have you heard about Loaders? I think that is exactly what you want to use ...

Upvotes: 2

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