FragmentStateAdapter and ViewPager2 is loading fragment slower than FragmentStatePagerAdapter and ViewPager

Question

In my app, am showing list of month calendar which can be scrollable to previous and next month. While swiping to previous and next, my fragments are loading smoothly and without any delay if I use FragmentStatePagerAdapter and ViewPager but it's now deprecated. So, I updated

ViewPager to ViewPager2

FragmentStatePagerAdapter to FragmentStateAdapter

After updating, I can see there is a delay in loading the fragments while swiping previous and next. But the same code works smoothly with FragmentStatePagerAdapter and ViewPager. I also tried mViewPager2.setOffscreenPageLimit(//Interger Value//) but no help.

Please assist me.

fragment_employee_months_holder

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/fragment_months_viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clickable="true"
        android:focusable="true" />

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:backgroundTint="@color/colorPrimary" />

</RelativeLayout>

EmployeeSummaryAdapter

class EmployeeSummaryAdapter(
    fragment: Fragment,
    private val mCodes: List<String>,
    private val mListener: NavigationListener,
    private val progressBarInterface: ProgressBarInterface
) : FragmentStateAdapter(fragment) {

    private val mFragments = SparseArray<EmployeeSummaryFragment>()

    override fun createFragment(position: Int): EmployeeSummaryFragment {
        val bundle = Bundle()
        val code = mCodes[position]
        bundle.putString(DAY_CODE, code)

        val fragment = EmployeeSummaryFragment(progressBarInterface)
        fragment.arguments = bundle
        fragment.listener = mListener
        mFragments.put(position, fragment)
        
        return fragment
    }

    override fun getItemCount(): Int = mCodes.size

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }
}

EmployeeSummaryFragmentHolder

class EmployeeSummaryFragmentHolder : MyFragmentHolder(), NavigationListener, ProgressBarInterface {

    private var viewPager2: ViewPager2? = null
    private lateinit var mEmployeeSummaryAdapter: EmployeeSummaryAdapter
    private lateinit var mView: View

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        currentDayCode = Formatter.getTodayCode()
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        mView = inflater.inflate(R.layout.fragment_employee_months_holder, container, false)
        viewPager2 = mView.fragment_months_viewpager
        viewPager2!!.id = (System.currentTimeMillis() % 100000).toInt()

        Handler(Looper.getMainLooper()).postDelayed({
            setupFragment()
        }, 0)

        return mView
    }

    private fun setupFragment() {
        val codes = getMonths(currentDayCode)
        mEmployeeSummaryAdapter = EmployeeSummaryAdapter(this, codes, this, this)
        viewPager2.apply {
            viewPager2!!.adapter = mEmployeeSummaryAdapter

            val myPageChangeCallback = object : ViewPager2.OnPageChangeCallback() {
                override fun onPageScrollStateChanged(state: Int) { }
                override fun onPageScrolled(position: Int, positionOffset: Float, 
                                              positionOffsetPixels: Int) { }
                override fun onPageSelected(position: Int) {   }
            }
            viewPager2!!.registerOnPageChangeCallback(myPageChangeCallback)
        }
    }
}

EmployeeSummaryFragment

class EmployeeSummaryFragment(val progressBarInterface: ProgressBarInterface) :
    Fragment(), MonthlyCalendar {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = inflater.inflate(R.layout.fragment_employee_month, container, false)
        ...
        ...        
        return view
    }

    override fun onResume() {
        super.onResume()
        ...
        ...
    }
}

score 1 · Accepted Answer · answered Aug 24 '21 at 22:24

1

I tried to look into your code and I didn't find anything suspicious, but you definitely need to set your mViewPager2.setOffscreenPageLimit(//Interger Value//) into your EmployeeSummaryFragmentHolder.

viewpager2.offscreenPageLimit = 2

answered Aug 24 '21 at 22:24

Henrique Vasconcellos

1,144
1
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13

Yeah, I tried adding as you mentioned but still facing the same issue – Rasool Mohamed Aug 25 '21 at 08:27
1

Are you using the latest viewpager2 library? Other suggestion is try to use debugging and/or reduce your setup complexity? Maybe insert a Log.D in your EmployeeSummaryFragment createView so you can see when the fragment is created? with offscreenPageLimit = 2 the second and third one should be created when you are still in the first one.. – Henrique Vasconcellos Aug 25 '21 at 14:42
1

One extra thing, the onResume on EmployeeSummaryFragment is only get called when the fragment itself is displayed, so if you have any loading process you should move to onViewCreated. – Henrique Vasconcellos Aug 25 '21 at 15:29
1

Thanks a lot, I checked in debugging that 1. onResume() is called in all the loaded fragments when I use FragmentStatePagerAdapter and ViewPager. 2. But in FragmentStateAdapter and ViewPager2, onResume() is called only if that fragment is visible on UI. 3. I have loading process in onResume() now I have moved it to onViewCreated() and now it's loading without any delay. Accepted and Upvoted your answer and comments. – Rasool Mohamed Aug 26 '21 at 05:54

FragmentStateAdapter and ViewPager2 is loading fragment slower than FragmentStatePagerAdapter and ViewPager

1 Answers1