FragmentStatePagerAdapter

public abstract class FragmentStatePagerAdapter
extends PagerAdapter

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:

public class FragmentStatePagerSupport 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() {
            public void onClick(View v) {
                mPager.setCurrentItem(0);
            }
        });
        button = (Button)findViewById(R.id.goto_last);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                mPager.setCurrentItem(NUM_ITEMS-1);
            }
        });
    }

    public static class MyAdapter extends FragmentStatePagerAdapter {
        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @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 onActivityCreated(Bundle savedInstanceState) {
            super.onActivityCreated(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">

    <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="0px"
            android:layout_weight="1">
    </android.support.v4.view.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 emtpy -->
        <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

Inherited constants
From class android.support.v4.view.PagerAdapter int POSITION_NONE int POSITION_UNCHANGED

Inherited methods
From class android.support.v4.view.PagerAdapter void destroyItem(View container, int position, Object object) This method is deprecated. Use destroyItem(ViewGroup, int, Object) void destroyItem(ViewGroup container, int position, Object object) Remove a page for the given position. void finishUpdate(View container) This method is deprecated. Use finishUpdate(ViewGroup) void finishUpdate(ViewGroup container) Called when the a change in the shown pages has been completed. abstract int getCount() Return the number of views available. int getItemPosition(Object object) Called when the host view is attempting to determine if an item's position has changed. CharSequence getPageTitle(int position) This method may be called by the ViewPager to obtain a title string to describe the specified page. float getPageWidth(int position) Returns the proportional width of a given page as a percentage of the ViewPager's measured width from (0.f-1.f] Object instantiateItem(ViewGroup container, int position) Create the page for the given position. Object instantiateItem(View container, int position) This method is deprecated. Use instantiateItem(ViewGroup, int) abstract 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 notifyDataSetChanged() This method should be called by the application if the data backing this adapter has changed and associated views should update. void registerDataSetObserver(DataSetObserver observer) Register an observer to receive callbacks related to the adapter's data changing. 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 setPrimaryItem(View container, int position, Object object) This method is deprecated. Use setPrimaryItem(ViewGroup, int, Object) void startUpdate(ViewGroup container) Called when a change in the shown pages is going to start being made. void startUpdate(View container) This method is deprecated. Use startUpdate(ViewGroup) void unregisterDataSetObserver(DataSetObserver observer) Unregister an observer from callbacks related to the adapter's data changing.
From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long millis, int nanos) Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed. final void wait(long millis) Causes the current thread to wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed. final void wait() Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object.

Public constructors

FragmentStatePagerAdapter (FragmentManager fm)

Public methods

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

void finishUpdate (ViewGroup container)

Fragment getItem (int position)

Object instantiateItem (ViewGroup container, 
                int position)

boolean isViewFromObject (View view, 
                Object object)

void restoreState (Parcelable state, 
                ClassLoader loader)

Parcelable saveState ()

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

void startUpdate (ViewGroup container)