android View pager load two pages at a time into memory.i want to load one page at a time and call when page scrolled is it possible?
how can i load one page at a time when user scrolled then call second fragment?
actually it is 3. view pager always load 3 pages or to be exact 3 fragments into memory. this insures user doesn't encounter a frame drop. but there is a catch:
we have two kind of view pager adapter: FragmentPagerAdapter and FragmentStatePagerAdapter .
if you have fragments with heavily content i suggest FragmentStatePagerAdapter because it doesn't load all 3 fragments together. it loads the first one and the save only the states of the other two. its better in case you want to manage memory for heavily content Fragments
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I have several pages some 8 pages on my dashboard containing viewpager and all have recycler view on it. The problem is when I swipe through viewpager, both swiping and recycler view setting adapter on the page happens at the same time on same ui thread due to which swiping lags and hence there is no smooth swiping and loading experience.
Things I tried using:
1. I tried putting delay to load the data but when swiping through, the previous fragment loads data due to which the ui lags again.
2. I also used setoffscreenpagelimit but I have some 8 pages and loading all at once or even some takes time to open the dashboard.
3. I tried using addOnPageChangeListener of the viewpager. But it lags the most.
Currently i am loading data when fragment is visible i.e in setUserVisibleHint method. I want to have a smooth swiping and loading experience. Help needed.
Thanks very much.
I have an Activity with ViewPager and three Fragments with-in. One Fragment contains ListView with custom CursorAdapter which loads data from database.
I've noticed that my cursor adapter loads data every time I switch Fragments in ViewPager. I think that it's normal and is due to the fact that every Fragment has its own lifecycle.
Regarding this it will be great pleasure for me if the users of the stackoverflow explain about their experience or best practices at all.
Thanks!
ViewPagers maintain the state of only certain number of fragments, which defaults to 1 for both sides of the current selected fragment. For example, if you have 3 fragments, when the first is selected, only first two fragments will be instantiated and have the listview data loaded. Alternatively, if you have the second fragment selected, the first and the third will be instantiated. If you switch to the third fragment, the second fragment will be retained, but the first one will be lost. However, you can set the number of fragments to be retained with calling setOffscreenPageLimit method on viewPager with any number of fragments to retain you need. Though you should remember, that setting the number too high may cause your app to consume too much memory.
For example, if you want your fragment to not reload listview content from db while switching fragments and you have 3 framents in your viewPager, you may write the following code:
ViewPager mViewPager;
mViewPager.setOffscreenPageLimit(2);
I'm experiencing a really weird behavior and I suppose I'm missing something.
I have an activity that has a Fragment inside. This Fragment has a ViewPager which obviously hosts other Fragments.
To populate that ViewPager I need info from four tables. Once the first loader finishes loading (let's call it 0), I init the other loaders.
The user swipes through the pages and when he/she reaches the last page, the Fragment that is loaded on that last page inits loader 0 again, which takes a huge amount of time to reach onLoaderFinished. If I load that "last page fragment" without being inside the ViewPager, it loads instantly, as expected.
Is there a way to deal with this situation of a Fragment inside a ViewPager using the same Loader that was used to populate the ViewPager itself?
Thanks in advance.
Try calling setOffscreenPageLimit() in onCreate() (after initializing ViewPager). The OffscreenPageLimit sets the number of pages that should be retained to either side of the current page. With this all of your fragments will instantiate. Though you must not do so if there are large number of pages.
I solved the problem by not calling the Loader inside the Fragment and passing the array of data I wanted from the database in a Bundle as a Serializable.
I'm using ViewPager that holds 3 fragments, each fragment loads a list. The problem is when the application runs for the first time and I swipe to the next fragment, this fragment needs sometime to load (about 2 seconds) before its view is visible. This is a very weird behavior. All I want is once the app has started, all fragments in ViewPager should be ready for user so when they swipe through fragments, there's no wait time. How can I do that?
Just call setOffscreenPageLimit() in onCreate() (after initializing ViewPager). The OffscreenPageLimit sets the number of pages that should be retained to either side of the current page (in your case 2). With this all of your fragments will be instantiate.
(An other (highly recommended) possibility is to increase the performance of your lists or listadapters, because a loading time of 2 seconds doesn't sound good)
I'm using ViewPager in Activity, whose adapter is a subclass of FragmentStatePagerAdapter. I have only three pages and each page show a view generated by Fragment(not complicated view).
My issue is: every time when I load the viewpager, I have to wait nearly 3 seconds before I can swipe left/right. The time interval between onCreate and onResume is less than 0.3 second
My question is: what's the potential root causes for this kind of delay?
Thanks
If you could post some code that would be great, but if i was going to take a stab...
I would say that you have many items in the adapter, and you have set the setOffscreenPageLimit(int) too high, and the viewpager is loading the fragments of too many pages.