Hello all, I’ve got one weird issue with `ViewPage...

# android

[antoniomarin]

Hello all,
I’ve got one weird issue with ViewPager2 and I cannot make any sense of it, I’ve got separate Activity that holds ViewPager2 which contains fragments. That means destroying that activity with finish() closes ViewPager2 as well.
Now what I’ve got is beyond me, everything works fine when I start it for the first time, but if I close it and reopen my observables in the fragments won’t emit any changes, tho everything is created fine?. I’ve pinpointed issue to the createFragment method where commented part works but non commented doesn’t?

class PagerAdapter( 
    fragmentActivity: FragmentActivity,
    private val items: List<PagerAdapterFragment>
    //private val items: List<Int>
) : FragmentStateAdapter(fragmentActivity) {

    override fun createFragment(position: Int): Fragment {
        return items[position].fragment
//        return when (position) {
//            0 -> Fragment1.newInstance()
//            1 -> Fragment2.newInstance()
//            2 ->  PlaceholderFragment.newInstance("Retention information screen")
//            else ->  PlaceholderFragment.newInstance("Else")
//        }
    }

    data class PagerAdapterFragment(val id: Long, val fragment: Fragment)

[antoniomarin]

Oke fixed it with:

override fun createFragment(position: Int): Fragment {
     return when (items[position].id) {
          ID_FRAG_1 -> Fragment1.newInstance()
          ID_FRAG_2 -> Fragment2.newInstance()
          ID_FRAG_3 -> Fragment3.newInstance()
          else -> PlaceholderFragment.newInstance("Else")
        }
    }

I don’t understand completely whats going on, tried debugging couldn’t find anything useful. I guess it needs else as fail safe tho fragments were initialising without it just fine

[Ian Lake]

You must always return a brand new Fragment instance from createFragment, that's why it is called create and not get

[antoniomarin]

Hi @Ian Lake thanks for reply, that get was returning newIstance() of a Fragment. This is basically the same code, and when running the app Fragments were initialised properly, just for some reason observing wasn’t working.

[Ian Lake]

Well, it very much looked like you were passing in a set of Fragment instances and calling items[position].fragment to return a previously created instance...not a brand new instance every single time createFragment was called