FragmentStateAdapter not recreating currentFragment after notifyDataSetChanged

Question

I have a FragmentStateAdapter as the adapter of a ViewPager2.

class DefaultFragmentStateAdapter(fragment: Fragment) : FragmentStateAdapter(fragment) {

    var items = listOf<Fragment>()
       set(value) {
           field = value
           notifyDateSetChanged()
       }

    override fun getItemCount(): Int = items.size

    override fun createFragment(position: Int): Fragment = items[position]
}

The adapters item can change depending on the date a user has selected, so it needs to be dynamical. What happens is that after I call adapter.items = {new_fragments} current fragment is not reloaded, only after I go to one of the last pages in the ViewPager and return to the first page can I see the updated fragment. The current fragment does not update when notifyDataSetChanged is called.

How can I manage to update current displayed fragment?

Answer 1

I had to override the following two methods...

override fun getItemId(position: Int): Long {
    return items[position].id
}

override fun containsItem(itemId: Long): Boolean = items.any { it.id == itemId }

... to make it work!