FragmentStatePagerAdapter

abstract class FragmentStatePagerAdapter : PagerAdapter

kotlin.Any
↳	androidx.viewpager.widget.PagerAdapter
	↳	androidx.fragment.app.FragmentStatePagerAdapter

Implementation of PagerAdapter that uses a Fragment to manage each page. This class also handles saving and restoring of fragment's state.

This version of the pager is more useful when there are a large number of pages, working more like a list view. When pages are not visible to the user, their entire fragment may be destroyed, only keeping the saved state of that fragment. This allows the pager to hold on to much less memory associated with each visited page as compared to FragmentPagerAdapter at the cost of potentially more overhead when switching between pages.

When using FragmentPagerAdapter the host ViewPager must have a valid ID set.

Subclasses only need to implement getItem(int) and getCount() to have a working adapter.

Here is an example implementation of a pager containing fragments of lists:

The R.layout.fragment_pager resource of the top-level fragment is:

The R.layout.fragment_pager_list resource containing each individual fragment's layout is:

Summary

Constants
static Int	BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT Indicates that only the current fragment will be in the Lifecycle.State#RESUMED state.
static Int	BEHAVIOR_SET_USER_VISIBLE_HINT Indicates that Fragment#setUserVisibleHint(boolean) will be called when the current fragment changes.

Inherited constants
From class PagerAdapter Int POSITION_NONE Int POSITION_UNCHANGED

Public constructors
<init>(@NonNull fm: FragmentManager) Constructor for FragmentStatePagerAdapter that sets the fragment manager for the adapter.
<init>(@NonNull fm: FragmentManager, behavior: Int) Constructor for FragmentStatePagerAdapter.

Public methods
open Unit	destroyItem(@NonNull container: ViewGroup, position: Int, @NonNull object: Any)
open Unit	finishUpdate(@NonNull container: ViewGroup)
abstract Fragment	getItem(position: Int) Return the Fragment associated with a specified position.
open Any	instantiateItem(@NonNull container: ViewGroup, position: Int)
open Boolean	isViewFromObject(@NonNull view: View, @NonNull object: Any)
open Unit	restoreState(@Nullable state: Parcelable?, @Nullable loader: ClassLoader?)
open Parcelable?	saveState()
open Unit	setPrimaryItem(@NonNull container: ViewGroup, position: Int, @NonNull object: Any)
open Unit	startUpdate(@NonNull container: ViewGroup)

Inherited functions

From class PagerAdapter Unit destroyItem(@NonNull container: View, position: Int, @NonNull object: Any) Remove a page for the given position. The adapter is responsible for removing the view from its container, although it only must ensure this is done by the time it returns from finishUpdate(View). Unit finishUpdate(@NonNull container: View) Called when the a change in the shown pages has been completed. At this point you must ensure that all of the pages have actually been added or removed from the container as appropriate. Int getCount() Return the number of views available. Int getItemPosition(@NonNull object: Any) Called when the host view is attempting to determine if an item's position has changed. Returns POSITION_UNCHANGED if the position of the given item has not changed or POSITION_NONE if the item is no longer present in the adapter. The default implementation assumes that items will never change position and always returns POSITION_UNCHANGED.