I'd like to cache a fragment view. My Activity has swipeable tabs and each tab calls a different fragment. But when i swipe between tabs the transition seems a quite slow because of the destruction of the fragment view, that is rebuilded during the swipe operation. Does anyone know how can i cache the view of each fragment to prevent this issue?
I work with library support v4 and api 14
I tried to implement a constructor for the fragments, called by the activity container of the fragments: i call the constructor, the fragments are created as variable of the activity class and then, whenever a fragment has to show itself, the activity class returns the fragment object i created before, but this doesn't improve my application a lot because the view of the fragment is destroyed anyway
This is because internally by default the pager loads a maximum of 3 pages (fragments) at the time:
the one displaying, previous and next so if you have 5 fragments this will happen while you move from first to last: (where x is a loaded fragment)
xx000
->
xxx00
->
0xxx0
->
00xxx
->
000xx
Try using
myPager.setOffscreenPageLimit(ITEMS_COUNT-1);
This will tell the pager to keep all of them in memory and not destroy/create with every swipe (keep a close look on the memory management)
Related
i have an Activity which haves several Fragments and am using PagerAdapter for organising this Fragments , i got to know when my activity, loads all of my Fragment's codes also gets executed even when am at first Fragment at that time my whole codes of all fragment 2 or 3 also got executed which are in the onCreateView of my Fragment so can we stop this behaviour i want to execute this codes only when user selects that particular fragment
you can limit your pager by calling this method default load number is 3
yourPager.setOffscreenPageLimit([number of pages]);
if you want just one page without preload try this link by TejjD
I am trying to implement swipe views with 2 tabs. For that, I am using view pager with 2 fragments. Now, the problem is that as soon as the main activity is opened (that contains those two tabs), onCreateView function is called for both the fragments. Please help me as how can I avoid calling of onCreateView of second fragment when one is in use.
Thanks,
Arpit
ViewPager retains the fragment to the left and to the right of the current view by default. This is to reduce a choppy user experience - that way you can begin swiping left or right and immediately see what is there without delay.
It is possible to disable (or increase the number of fragments to be retained) with setOffscreenPageLimit(0), but seriously consider if this is the right approach.
I have implemented an activity that displays fragments in a viewpager. The activity initially displays 5 fragments of a given type (type A). Each type A fragment contains a list of information. When a button is pressed, the fragments are replaced with another tpye of fragments, type B (i.e., fragments that use a different layout and display different information are loaded).
I have implemented this with a ViewPager and a custom FragmentStatePagerAdapter. The custom FragmentStatePagerAdapter overrides the getCount, instantiateItem, getItem, getItemPosition, etc. functions and all works fine. When I press the button the views switch from fragment type A to fragment type B. In order to do this I am using a replace fragment transaction and I also call notifyDataSetChanged on the adapter. The switch from type A to type B fragments is accomplished by checking which type of fragment I need to create in the adapter's getItem function. The problem is that the switching process (i.e., changing from fragment type A to fragment type B and vice versa) takes some time (around 2 seconds) - this delay is quite noticeable and annoying.
This occurs because the adapter's getItemPosition function returns POSITION_NONE. When POSITION_NONE is returned, the viewPager recreates the fragment. Furthermore, when the replace transaction is executed, all items of the adapter are removed and all new ones are recreated. The same happens when I switch back to fragments type A.
Does anyone know if there is a better or faster way to do this? Using a FragmentPagerAdapter should not be a good solution since the number of fragments in the viewPager could grow.
I have commented out the updating of the fragments and the problem is gone so the problem is the time it takes to update the fragments. Is there a way to update the fragments asynchronously? That should take care of the problem.
The ViewPager instatiates by default a minimun count of Fragments. In general the left and right one of the current Fragment. So you don't need to care about the total number of Fragments.
You can control the total number with the ViewPager.setOffScreenPageLimit() method.
Also a AsyncTask seems to be a good idea to manage the intensiv work of your Fragments.
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)
In my application I am using ViewPager from the support library- v4
In main screen I have viewPager which got max 5 Fragment, all fragment belongs to one class ArticlePager
Now in main screen there are list on categories, now the content of the pager is based on that selection,
The problem I am having is, I have used FragmentPagerAdapterwhich stores the Fragment and if the fragment is already exist, It will return the old Fragment without recreating it. That things runs perfectly, but Problem Occurs # the time of orientation change.
For instance
If there are 5 View normally in every fragment For the given position, but There are also some which contains 2-3 views. Now if I change the orientation on page No. lets say 5 which contains only 3 view inside.
So, by now in every category on Page 5 I'll got the view containing 3 view, which is not something I want.
In my application each category contains the pagination
Is there any way such that i can destroy and recreate the Fragment on click of category? or any other work around
Thank you
OK thanks to open source I find my solution, FragmentPagerAdapter I have override the method instantiateItem and got the solution.
This can be easily achieved by FragmentStatePagerAdapter such that it doesn't store the fragment. It recreate it all the time, but I don't want that in 100's of page because of only few pages.
So if I understand correctly, your problem is that after rotation, the wrong set of fragments are in you ViewPager?
Why don't you check the current selected tab in onResume() or onStart() of your Activity, and create/assign a new PagerAdapter for you ViewPager with the correct fragments?