I use Viewpager2 With setup tablayout using TabLayoutMediator but the issue is
when I swipe viewpager first fragment to the second fragment here only call
current fragment's lifecycle methods, but when I click on tablayout
then call next fragment's lifecycle methods. I don't know why this happens?
This happens because the method that TabLayoutMediator uses to move to the selected fragment causes the RecyclerView to cache the next Fragment as it uses Smooth Scrolling.
This should not be a problem UNLESS you are doing something in the wrong part of the Fragment's lifecycle. If you only want do something when a Fragment is displayed then only do it in the Fragments onResume method as the behaviour you describe will only take the cached Fragment to "Started" state.
Related
I have this structure
Tabs with fragments
---(one)Fragment with ViewPager2
------- Fragments inside ViewPager2
When I change between ViewPager's fragments, onResume and onPause are called just fine.
Problem comes when I click on another tab to load another fragment. When I do that for some reason the fragment that hosts the ViewPager will receive onHiddenChanged callback but its children will not receive any callback.
I've tried all 3 constructors for FragmentStateAdapter, none of them helped and I have no idea how I will notify viewpager's fragments for such a lifecycle change. Any ideas?
I am using 4 fragments in MainActivity with viewPager where viewPager is not scrollable, and I have four more fragments inside Second Fragment of MainActivity fragment. I am calling API in my all fragments in the onCreateView method. But when activity initialized so all fragments onCreateView method run, how to fix it because I want when the fragment is visible than my API call.
I already tried setUserVisibleHint method it's also working when activity initialized.
Should I use frame layout or anything else to fix this problem?
if i understood you good then you want to call your api when fragments are visible.
if yes then use
viewPager.addOnPageChangeListener
and onPageSelected(int position) callback then just make good condition which call you'r api
edit: changed adapter to viewPager
I think you need to put your api calls method in onResume in each fragment that will be fired when your fragment is on the top of fragments stack (Shown).
I have something that has me stumped. I have a Fragment (Fragment A) that has ViewPager that contains three fragments (for swiping left/right). So, if within another fragment, in the onBackPressed() method, I do a getFragmentManager().popBackStack() call, Fragment A will be again be visible (with the ViewPager of sub-fragments) which is the desired state. However, there is no method with Fragment A or within the ViewPager that indicates that Fragment A/ViewPager is again visible.
None of the fragment methods referenced in the Fragment lifecycle (http://developer.android.com/guide/components/fragments.html) that should be called when "The fragment returns the layout from the back stack" or any of the methods called within OnPageChangeListener (yes, I do call viewPager.setOnPageChangeListener(this) within Fragment A's onCreateView).
Thoughts on where I could look?
I have an app with a ViewPager that is added to the layout, then later replaced by another fragment, with the change added to the transaction back stack. I have Log statements in each of the lifecycle methods of the pager. When the Back button is pressed and the pager is returned to the layout, my logcat output shows these methods called for the pager: onCreateView(), onActivityCreated(), onStart(), onResume(). Note that when a fragment goes into the back stack, its view is destroyed, but the fragment object is not destroyed, so when the fragment returns from the back stack, there is no call to onCreate().
This behavior is consistent with the lifecycle diagram in the Fragment Guide. You should be able to use the call to onResume() as an indication that your pager is visible. I can only suggest that you add debug output to the lifecycle methods for your pager and look at the output. If you think its wrong, please add it to the post of your question. Also indicate what fragment transaction method(s) you are using. If by chance you are using hide() instead of remove() or replace(), then the lifecycle events are different and you may need to use onHiddenChanged().
I implemented View Pager with fragment child A/B/C. To get selection of default Fragment(say A) I use mViewPager.setCurrentItem(position) and it work fine. But on this Second Fragment (B) view methods onViewCreated and setUserVisibleHint calling automatically.
Is there any way to prevent this !
You can try invoking ViewPager.setOffscreenPageLimit(0), which will no longer pre-load non-visible Fragments. The default value for the off-screen page limit is 1, so that should be the reason why the onViewCreated() and setUserVisibleHint() methods are being called for your other fragments.
I am implementing Tab Layout with Swipeable Views in android. For implementation I had followed
AndroidHive
and
Tabs and swipe views.
But with both, I am facing the same problem. I am having 3 fragments but when my application run, onCreateView of 1st and 2nd Fragment called instead of only of 1st fragment's. When I swipe and go to 2nd fragment, onCreateView of 3rd Fragments get called.
So, whatever I code in 2nd fragment execute in the first fragment view. I researched and came to know that it happen to keep the next fragment into memory for smooth animation. But I am wondering, where I would code in the fragment so that it will execute only once or how to restrict Fragment getItem() method to be called only once. What can be the solution for this?
According to the Fragment's documentation you can implement the onCreate() link:
The system calls this when creating the fragment. Within your implementation, you should initialize essential components of the fragment that you want to retain when the fragment is paused or stopped, then resumed.
This should fix your problem, because i guess you now only use the onCreateView which might be called more than once.
For more information you can check the Fragment's lifecycle or documentation