java.lang.Object | ||
↳ | android.support.v4.view.PagerAdapter | |
↳ | android.support.v13.app.FragmentPagerAdapter |
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 getCount()
to have a working adapter.
Here is an example implementation of a pager containing fragments of lists:
public class FragmentPagerSupport extends Activity { 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(getFragmentManager()); 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 FragmentPagerAdapter { 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>
[Expand]
Inherited Constants | |||||||||||
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From class
android.support.v4.view.PagerAdapter
|
Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Remove a page for the given position.
| |||||||||||
Called when the a change in the shown pages has been completed.
| |||||||||||
Return the Fragment associated with a specified position.
| |||||||||||
Return a unique identifier for the item at the given position.
| |||||||||||
Create the page for the given position.
| |||||||||||
Determines whether a page View is associated with a specific key object
as returned by
instantiateItem(ViewGroup, int) . | |||||||||||
Restore any instance state associated with this adapter and its pages
that was previously saved by
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.
| |||||||||||
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.
| |||||||||||
Called when a change in the shown pages is going to start being made.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
android.support.v4.view.PagerAdapter
| |||||||||||
From class
java.lang.Object
|
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(ViewGroup)
.
container | The containing View from which the page will be removed. |
---|---|
position | The page position to be removed. |
object | The same object that was returned by
instantiateItem(View, int) .
|
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.
container | The containing View which is displaying this adapter's page views. |
---|
Return the Fragment associated with a specified position.
Return a unique identifier for the item at the given position.
The default implementation returns the given position. Subclasses should override this method if the positions of items can change.
position | Position within this adapter |
---|
Create the page for the given position. The adapter is responsible
for adding the view to the container given here, although it only
must ensure this is done by the time it returns from
finishUpdate(ViewGroup)
.
container | The containing View in which the page will be shown. |
---|---|
position | The page position to be instantiated. |
Determines whether a page View is associated with a specific key object
as returned by instantiateItem(ViewGroup, int)
. This method is
required for a PagerAdapter to function properly.
view | Page View to check for association with object |
---|---|
object | Object to check for association with view |
view
is associated with the key object object
Restore any instance state associated with this adapter and its pages
that was previously saved by saveState()
.
state | State previously saved by a call to saveState() |
---|---|
loader | A ClassLoader that should be used to instantiate any restored objects |
Save any instance state associated with this adapter and its pages that should be restored if the current UI state needs to be reconstructed.
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.
container | The containing View from which the page will be removed. |
---|---|
position | The page position that is now the primary. |
object | The same object that was returned by
instantiateItem(View, int) .
|
Called when a change in the shown pages is going to start being made.
container | The containing View which is displaying this adapter's page views. |
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