FragmentPagerAdapter

public abstract class FragmentPagerAdapter
extends PagerAdapter

java.lang.Object
   ↳ androidx.viewpager.widget.PagerAdapter
     ↳ androidx.fragment.app.FragmentPagerAdapter


This class is deprecated.
Switch to ViewPager2 and use FragmentStateAdapter instead.

Implementation of PagerAdapter that represents each page as a Fragment that is persistently kept in the fragment manager as long as the user can return to the page.

This version of the pager is best for use when there are a handful of typically more static fragments to be paged through, such as a set of tabs. The fragment of each page the user visits will be kept in memory, though its view hierarchy may be destroyed when not visible. This can result in using a significant amount of memory since fragment instances can hold on to an arbitrary amount of state. For larger sets of pages, consider FragmentStatePagerAdapter.

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

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

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

public class FragmentPagerSupport extends FragmentActivity {
    static final int NUM_ITEMS = 10;

    MyAdapter mAdapter;

    ViewPager mPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_pager);

        mAdapter = new MyAdapter(getSupportFragmentManager());

        mPager = (ViewPager)findViewById(R.id.pager);
        mPager.setAdapter(mAdapter);

        // Watch for button clicks.
        Button button = (Button)findViewById(R.id.goto_first);
        button.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mPager.setCurrentItem(0);
            }
        });
        button = (Button)findViewById(R.id.goto_last);
        button.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mPager.setCurrentItem(NUM_ITEMS-1);
            }
        });
    }

    public static class MyAdapter extends FragmentPagerAdapter {
        public MyAdapter(FragmentManager fm) {
            super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
        }

        @Override
        public int getCount() {
            return NUM_ITEMS;
        }

        @Override
        public Fragment getItem(int position) {
            return ArrayListFragment.newInstance(position);
        }
    }

    public static class ArrayListFragment extends ListFragment {
        int mNum;

        /**
         * Create a new instance of CountingFragment, providing "num"
         * as an argument.
         */
        static ArrayListFragment newInstance(int num) {
            ArrayListFragment f = new ArrayListFragment();

            // Supply num input as an argument.
            Bundle args = new Bundle();
            args.putInt("num", num);
            f.setArguments(args);

            return f;
        }

        /**
         * When creating, retrieve this instance's number from its arguments.
         */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            mNum = getArguments() != null ? getArguments().getInt("num") : 1;
        }

        /**
         * The Fragment's UI is just a simple text view showing its
         * instance number.
         */
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.fragment_pager_list, container, false);
            View tv = v.findViewById(R.id.text);
            ((TextView)tv).setText("Fragment #" + mNum);
            return v;
        }

        @Override
        public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            setListAdapter(new ArrayAdapter<String>(getActivity(),
                    android.R.layout.simple_list_item_1, Cheeses.sCheeseStrings));
        }

        @Override
        public void onListItemClick(ListView l, View v, int position, long id) {
            Log.i("FragmentList", "Item clicked: " + id);
        }
    }
}

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical" android:padding="4dip"
        android:gravity="center_horizontal"
        android:layout_width="match_parent" android:layout_height="match_parent">

    <androidx.viewpager.widget.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="0px"
            android:layout_weight="1">
    </androidx.viewpager.widget.ViewPager>

    <LinearLayout android:orientation="horizontal"
            android:gravity="center" android:measureWithLargestChild="true"
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="0">
        <Button android:id="@+id/goto_first"
            android:layout_width="wrap_content" android:layout_height="wrap_content"
            android:text="@string/first">
        </Button>
        <Button android:id="@+id/goto_last"
            android:layout_width="wrap_content" android:layout_height="wrap_content"
            android:text="@string/last">
        </Button>
    </LinearLayout>
</LinearLayout>

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:drawable/gallery_thumb">

    <TextView android:id="@+id/text"
        android:layout_width="match_parent" android:layout_height="wrap_content"
        android:gravity="center_vertical|center_horizontal"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="@string/hello_world"/>

    <!-- The frame layout is here since we will be showing either
    the empty view or the list view.  -->
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
        android:layout_weight="1" >
        <!-- Here is the list. Since we are using a ListActivity, we
             have to call it "@android:id/list" so ListActivity will
             find it -->
        <ListView android:id="@android:id/list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:drawSelectorOnTop="false"/>

        <!-- Here is the view to show if the list is empty -->
        <TextView android:id="@android:id/empty"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="No items."/>

    </FrameLayout>

</LinearLayout>

Summary

Constants

int BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT

Indicates that only the current fragment will be in the Lifecycle.State.RESUMED state.

int BEHAVIOR_SET_USER_VISIBLE_HINT

This constant is deprecated. This behavior relies on the deprecated Fragment.setUserVisibleHint(boolean) API. Use BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT to switch to its replacement, FragmentTransaction.setMaxLifecycle(Fragment, Lifecycle.State).

Inherited constants

Public constructors

FragmentPagerAdapter(FragmentManager fm)

This constructor is deprecated. use FragmentPagerAdapter(FragmentManager, int) with BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT

FragmentPagerAdapter(FragmentManager fm, int behavior)

Constructor for FragmentPagerAdapter.

Public methods

void destroyItem(ViewGroup container, int position, Object object)

Remove a page for the given position.

void finishUpdate(ViewGroup container)

Called when the a change in the shown pages has been completed.

abstract Fragment getItem(int position)

Return the Fragment associated with a specified position.

long getItemId(int position)

Return a unique identifier for the item at the given position.

Object instantiateItem(ViewGroup container, int position)

Create the page for the given position.

boolean isViewFromObject(View view, Object object)

Determines whether a page View is associated with a specific key object as returned by instantiateItem(ViewGroup, int).

void restoreState(Parcelable state, ClassLoader loader)

Restore any instance state associated with this adapter and its pages that was previously saved by saveState().

Parcelable saveState()

Save any instance state associated with this adapter and its pages that should be restored if the current UI state needs to be reconstructed.

void setPrimaryItem(ViewGroup container, int position, Object object)

Called to inform the adapter of which item is currently considered to be the "primary", that is the one show to the user as the current page.

void startUpdate(ViewGroup container)

Called when a change in the shown pages is going to start being made.

Inherited methods

Constants

BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT

public static final int BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT

Indicates that only the current fragment will be in the Lifecycle.State.RESUMED state. All other Fragments are capped at Lifecycle.State.STARTED.

Constant Value: 1 (0x00000001)

BEHAVIOR_SET_USER_VISIBLE_HINT

public static final int BEHAVIOR_SET_USER_VISIBLE_HINT

This constant is deprecated.
This behavior relies on the deprecated Fragment.setUserVisibleHint(boolean) API. Use BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT to switch to its replacement, FragmentTransaction.setMaxLifecycle(Fragment, Lifecycle.State).

Indicates that Fragment.setUserVisibleHint(boolean) will be called when the current fragment changes.

Constant Value: 0 (0x00000000)

Public constructors

FragmentPagerAdapter

public FragmentPagerAdapter (FragmentManager fm)

This constructor is deprecated.
use FragmentPagerAdapter(FragmentManager, int) with BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT

Constructor for FragmentPagerAdapter that sets the fragment manager for the adapter. This is the equivalent of calling FragmentPagerAdapter(FragmentManager, int) and passing in BEHAVIOR_SET_USER_VISIBLE_HINT.

Fragments will have Fragment.setUserVisibleHint(boolean) called whenever the current Fragment changes.

Parameters
fm FragmentManager: fragment manager that will interact with this adapter

FragmentPagerAdapter

public FragmentPagerAdapter (FragmentManager fm, 
                int behavior)

Constructor for FragmentPagerAdapter. If BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT is passed in, then only the current Fragment is in the Lifecycle.State.RESUMED state. All other fragments are capped at Lifecycle.State.STARTED. If BEHAVIOR_SET_USER_VISIBLE_HINT is passed, all fragments are in the Lifecycle.State.RESUMED state and there will be callbacks to Fragment.setUserVisibleHint(boolean).

Parameters
fm FragmentManager: fragment manager that will interact with this adapter