I'm using a Fragment on my Activity that will have a picture "swiper". I've created a FragmentStatePagerAdapter which I'm trying to call from this Fragment and for some reason my getItem() method is never being called.
I've searched and found that I need to use getChildFragmentManager() when instantiating my FragmentStatePagerAdapter because I'm calling it from a Fragment. I've tried this as well as getSupportFragmentManager() with no luck from either.
Any ideas?
here's my Fragment that I'm using on my MainActivity with the method that shoudl setup the FragmentStatePagerAdapter:
public class PhotoFlipper extends Fragment {
// properties and fields
// primitive types
String currentImage;
int friendShareType = 0;
ImageView share;
ViewPager pager;
PhotoFlipperItemAdapter pagerAdapter;
LatLng itemPosition;
Activity activity;
FragmentActivity fragActivity;
public ArrayList<MarkerModel> picsAndVids;
// end properties and fields
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View photoFlipperFragmentView = inflater.inflate(R.layout.photo_flipper_layout, container, false);
InitializeFragment(photoFlipperFragmentView);
return photoFlipperFragmentView;
}
private void InitializeFragment(View photoFlipperFragmentView) {
activity = getActivity();
fragActivity = (FragmentActivity)activity;
pager = (ViewPager)photoFlipperFragmentView.findViewById(R.id.photoflipper_pager);
share = (ImageView)photoFlipperFragmentView.findViewById(R.id.photoflipper_share);
share.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
IPictureFlipper iPictureFlipper = (IPictureFlipper)activity;
iPictureFlipper.ShareVideoOrImage(friendShareType, itemPosition, currentImage);
}
});
}
#Override
public void onHiddenChanged(boolean hidden) {
super.onHiddenChanged(hidden);
if (hidden) {
pager.setVisibility(View.GONE);
}
}
public void SetTappedPicture(int index) {
pagerAdapter = new PhotoFlipperItemAdapter(getChildFragmentManager(), picsAndVids, picsAndVids.size());
pager.setAdapter(pagerAdapter);
pager.setCurrentItem(index);
pager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
}
});
}
}
And here's my FragmentStatePagerAdapter:
public class PhotoFlipperItemAdapter extends FragmentStatePagerAdapter {
ArrayList<MarkerModel> _markers;
int NUM_PAGES;
String TAG = "home";
public PhotoFlipperItemAdapter(FragmentManager fm, ArrayList<MarkerModel> markers, int numpages){
super(fm);
Log.d(TAG,"in adapter in constructor");
_markers = markers;
NUM_PAGES = numpages;
}
#Override
public Fragment getItem(int position) {
Log.d(TAG,"in adapter in get item");
Fragment fragment = PhotoFlipperItemFragment.create(position, _markers);
return fragment;
}
#Override
public int getCount() {
Log.d(TAG,"in adapter in get count: "+NUM_PAGES);
return NUM_PAGES;
}
}
logcat is showing me that NUM_PAGES is > 0 so that's not my issue. I see my log in the constructor and in getCount() but nothing in getItem().
TIA
I got this sorted out. I was hiding my fragment in my InitializeActivity() right after I added it to my FragmentManager so it was never fully building the Fragment with the ViewPager etc.
I'm going to have to come up with a different solution for hiding/showing the fragment but that was my problem.
I am using ViewPager with my fragments. All fragments has animation and it does not work when switching back maybe because ViewPager saves somehow state of near Fragments, do you have some idea how to avoid it?
getItemPosition() doesn't make anything in this case
private class MyFragmentPagerAdapter extends FragmentPagerAdapter {
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public CharSequence getPageTitle(int position) {
return null;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return GetStartedOneFragment.newInstance();
case 1:
return GetStartedTwoFragment.newInstance();
case 2:
return GetStartedThreeFragment.newInstance();
case 3:
return GetStartedFourFragment.newInstance();
case 4:
return GetStartedFiveFragment.newInstance();
case 5:
return GetStartedSixFragment.newInstance();
default:
return GetStartedOneFragment.newInstance();
}
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
}
I used a Fragment as a slider content, see the sample code below. Feel free to ask more details if required.
I have 4 flight modes in the example. The ViewPager is used with the associated adapter (ScreenSlidePagerAdapter).
You can see the app in the Play Store to see the slider (search "Flight Recorder 24").
// In the main fragment java code
private View headerView;
private ViewPager mPager;
public ScreenSlidePagerAdapter mPagerAdapter;
// ...
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
super.onCreateView(inflater, container, savedInstanceState);
View mainView = inflater.inflate(R.layout.monitoring_fragment,container, false);
// The header of the list
View view = inflater.inflate(R.layout.header_monitoring_fragment, mListView, false);
headerView = view;
//...
mPager = (ViewPager) view.findViewById(R.id.pager);
FragmentManager fm = getChildFragmentManager();
mPagerAdapter = new ScreenSlidePagerAdapter(fm);
mPager.setAdapter(mPagerAdapter);
mPager.setCurrentItem(UserConfiguration.getUserConf().getPositionFromFlightMode());
// Attach the page change listener inside the activity
mPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener()
{
// This method will be invoked when a new page becomes selected.
#Override
public void onPageSelected(int position)
{
int flight_mode = UserConfiguration.getFlightModeFromPosition(position);
UserConfiguration.getUserConf().setFlightMode(flight_mode);
}
// This method will be invoked when the current page is scrolled
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
{
// Code goes here
}
// Called when the scroll state changes:
// SCROLL_STATE_IDLE, SCROLL_STATE_DRAGGING, SCROLL_STATE_SETTLING
#Override
public void onPageScrollStateChanged(int state)
{
// Code goes here
}
});
// ...
}
// ...
// Slider adapter
private class ScreenSlidePagerAdapter extends FragmentPagerAdapter
{
public ScreenSlidePagerAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public Fragment getItem(int position)
{
// position to flight mode
int flight_mode = UserConfiguration.getFlightModeFromPosition(position);
FlightModeFragment flightModeFragment = FlightModeFragment.newInstance(flight_mode);
return flightModeFragment;
}
public int getItemPosition(Object object)
{
return POSITION_NONE;
}
#Override
public int getCount()
{
return 4;
}
}
Then you have to create a Fragment with your slider content (here the class FlightModeFragment), it will be instanciated with an integer to identify the page embedded into a Bundle savedInstanceState (I have 4 pages).
public class FlightModeFragment extends Fragment
{
LinearLayout mainLayout;
ImageView live15minImageView;
ImageView modeImageView;
ImageView imageViewLeft;
ImageView imageViewRight;
private TextView textViewRecord;
private TextView textViewGps;
int flight_mode = UserConfiguration.AC_LISTENER_TRAVEL_RECORDER_MODE;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// handle fragment arguments
Bundle arguments = getArguments();
if(arguments != null)
{
flight_mode = arguments.getInt("flight_mode");
}
}
// ...
}
I'm making use of ViewPagerIndicator, and I have my adapter defined like this:
public class MyPagerAdapter extends FragmentPagerAdapter implements
IconPagerAdapter {
private final static String TAB_ITEMS[] = { "Tab 1", "Tab 2", "Tab 3", "Tab 4"};
private int count = TAB_ITEMS.length;
public MyPagerAdapter (FragmentManager fm) {
super(fm);
}
#Override
public int getIconResId(int index) {
// TODO Auto-generated method stub
return 0;
}
#Override
public Fragment getItem(int position) {
Fragment fragment = new BaseFragment();
return fragment;
}
#Override
public int getCount() {
return count;
}
And this is my activity that will contain my fragments:
public class MyActivity extends FragmentActivity implements
OnPageChangeListener {
private int tabPosition;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager pager = (ViewPager) findViewById(R.id.pager);
MyPagerAdapter adapter = new MyPagerAdapter (
getSupportFragmentManager());
pager.setAdapter(adapter);
UnderlinePageIndicator indicator = (UnderlinePageIndicator) findViewById(R.id.indicator);
indicator.setFades(false);
indicator.setViewPager(pager);
indicator.setOnPageChangeListener(this);
}
#Override
public void onPageScrollStateChanged(int state) {
// TODO Auto-generated method stub
}
#Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
// TODO Auto-generated method stub
}
#Override
public void onPageSelected(int position) {
// TODO Auto-generated method stub
setTabPosition(position);
Toast.makeText(MyActivity.this,
"Changed to page: " + position, Toast.LENGTH_SHORT).show();
}
public void setTabPosition(int position) {
this.tabPosition = position;
}
public int getTabPosition() {
return this.tabPosition;
}
}
Finally the definition of BaseFragment:
public class BaseFragment extends Fragment implements OnItemClickListener {
private final static String TAG = "BaseFragment";
private int tabPosition;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_base, container,
false);
return view;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
tabPosition = ((MyActivity) getActivity()).getTabPosition();
Toast.makeText(getActivity(), "page " + tabPosition, Toast.LENGTH_SHORT)
.show();
}
Now , this is my problem:
The toast in onPageSelected of the activity always shows the correct page when a new page is selected or swiped to.
However, the toast in my fragment only shows the correct page when you swipe to either page 1 or page 2. The only time it toasts page 0 is anytime the app is launched. After that, when the user swipes to page 0 or page 4, no toast is shown at all, not even an empty toast.
I wrote the getTabPosition() and setTabPosition() methods with the intention of getting the current selected tab position in the fragment, but it obviously doesn't work correctly hence I dont get toasts on pages 0 and 4.
My question is: how do I get the selected page position in my BaseFragment, since I need that position to load the appropriate data?
Hope I was clear enough?
Each Fragment will display a different set of data, then maybe it is a good idea to have one fragment for each. Here is what I did to display different Fragments for different data in the FragmentPagerAdapter:
#Override
public Fragment getItem(int index) {
Fragment fragment = null;
// Define the page for each index
switch(index){
case 0:
fragment = new Fragment1();
break;
case 1:
fragment = new Fragment2();
break;
case 2:
fragment = new Fragment3();
break;
}
This may not be the best approach but in your activity that holds reference to ViewPager try this:
public class TabbedViewActivity extends FragmentActivity {
ViewPager viewPager;
public static int tabIndex = 0;
#Override
protected void onCreate(Bundle bundle) {
......
viewPager = (ViewPager)findViewById(R.id.pager);
TabbedViewActivity.tabIndex = 0; // in the start index is always 0 unless coded otherwise
viewPager.setOnPageChangeListener(
new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
TabbedViewActivity.tabIndex = position;
}
});
}
Then you can always access this variable statically like this in your Fragment TabbedViewActivity.tabIndex
pager.getCurrentItem();
it return current fragment index
I'm using the v4 compatibility ViewPager in Android. My FragmentActivity has a bunch of data which is to be displayed in different ways on different pages in my ViewPager. So far I just have 3 instances of the same ListFragment, but in the future I will have 3 instances of different ListFragments. The ViewPager is on a vertical phone screen, the lists are not side-by-side.
Now a button on the ListFragment starts an separate full-page activity (via the FragmentActivity), which returns and FragmentActivity modifies the data, saves it, then attempts to update all views in its ViewPager. It is here, where I am stuck.
public class ProgressMainActivity extends FragmentActivity
{
MyAdapter mAdapter;
ViewPager mPager;
#Override
public void onCreate(Bundle savedInstanceState)
{
...
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.viewpager);
mPager.setAdapter(mAdapter);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
...
updateFragments();
...
}
public void updateFragments()
{
//Attempt 1:
//mAdapter.notifyDataSetChanged();
//mPager.setAdapter(mAdapter);
//Attempt 2:
//HomeListFragment fragment = (HomeListFragment) getSupportFragmentManager().findFragmentById(mAdapter.fragId[0]);
//fragment.updateDisplay();
}
public static class MyAdapter extends FragmentPagerAdapter implements
TitleProvider
{
int[] fragId = {0,0,0,0,0};
public MyAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public String getTitle(int position){
return titles[position];
}
#Override
public int getCount(){
return titles.length;
}
#Override
public Fragment getItem(int position)
{
Fragment frag = HomeListFragment.newInstance(position);
//Attempt 2:
//fragId[position] = frag.getId();
return frag;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE; //To make notifyDataSetChanged() do something
}
}
public class HomeListFragment extends ListFragment
{
...
public static HomeListFragment newInstance(int num)
{
HomeListFragment f = new HomeListFragment();
...
return f;
}
...
Now as you can see, my first attempt was to notifyDataSetChanged on the entire FragmentPagerAdapter, and this showed to update the data sometimes, but others I got an IllegalStateException: Can not perform this action after onSaveInstanceState.
My second attempt involed trying to call an update function in my ListFragment, but getId in getItem returned 0. As per the docs I tried by
acquiring a reference to the Fragment from FragmentManager, using
findFragmentById() or findFragmentByTag()
but I don't know the tag or id of my Fragments! I have an android:id="#+id/viewpager" for ViewPager, and a android:id="#android:id/list" for my ListView in the ListFragment layout, but I don't think these are useful.
So, how can I either:
a) update the entire ViewPager safely in one go (ideally returning the user to the page he was on before) - it is ok that the user see the view change.
Or preferably,
b) call a function in each affected ListFragment to update the ListView manually.
Any help would be gratefully accepted!
Barkside's answer works with FragmentPagerAdapter but doesn't work with FragmentStatePagerAdapter, because it doesn't set tags on fragments it passes to FragmentManager.
With FragmentStatePagerAdapter it seems we can get by, using its instantiateItem(ViewGroup container, int position) call. It returns reference to fragment at position position. If FragmentStatePagerAdapter already holds reference to fragment in question, instantiateItem just returns reference to that fragment, and doesn't call getItem() to instantiate it again.
So, suppose, I'm currently looking at fragment #50, and want to access fragment #49. Since they are close, there's a good chance the #49 will be already instantiated. So,
ViewPager pager = findViewById(R.id.viewpager);
FragmentStatePagerAdapter a = (FragmentStatePagerAdapter) pager.getAdapter();
MyFragment f49 = (MyFragment) a.instantiateItem(pager, 49)
OK, I think I've found a way to perform request b) in my own question so I'll share for others' benefit. The tag of fragments inside a ViewPager is in the form "android:switcher:VIEWPAGER_ID:INDEX", where VIEWPAGER_ID is the R.id.viewpager in XML layout, and INDEX is the position in the viewpager. So if the position is known (eg 0), I can perform in updateFragments():
HomeListFragment fragment =
(HomeListFragment) getSupportFragmentManager().findFragmentByTag(
"android:switcher:"+R.id.viewpager+":0");
if(fragment != null) // could be null if not instantiated yet
{
if(fragment.getView() != null)
{
// no need to call if fragment's onDestroyView()
//has since been called.
fragment.updateDisplay(); // do what updates are required
}
}
I've no idea if this is a valid way of doing it, but it'll do until something better is suggested.
Try to record the tag each time a Fragement is instantiated.
public class MPagerAdapter extends FragmentPagerAdapter {
private Map<Integer, String> mFragmentTags;
private FragmentManager mFragmentManager;
public MPagerAdapter(FragmentManager fm) {
super(fm);
mFragmentManager = fm;
mFragmentTags = new HashMap<Integer, String>();
}
#Override
public int getCount() {
return 10;
}
#Override
public Fragment getItem(int position) {
return Fragment.instantiate(mContext, AFragment.class.getName(), null);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
Object obj = super.instantiateItem(container, position);
if (obj instanceof Fragment) {
// record the fragment tag here.
Fragment f = (Fragment) obj;
String tag = f.getTag();
mFragmentTags.put(position, tag);
}
return obj;
}
public Fragment getFragment(int position) {
String tag = mFragmentTags.get(position);
if (tag == null)
return null;
return mFragmentManager.findFragmentByTag(tag);
}
}
If you ask me, the second solution on the below page, keeping track of all the "active" fragment pages, is better: http://tamsler.blogspot.nl/2011/11/android-viewpager-and-fragments-part-ii.html
The answer from barkside is too hacky for me.
you keep track of all the "active" fragment pages. In this case, you keep track of the fragment pages in the FragmentStatePagerAdapter, which is used by the ViewPager.
private final SparseArray<Fragment> mPageReferences = new SparseArray<Fragment>();
public Fragment getItem(int index) {
Fragment myFragment = MyFragment.newInstance();
mPageReferences.put(index, myFragment);
return myFragment;
}
To avoid keeping a reference to "inactive" fragment pages, we need to implement the FragmentStatePagerAdapter's destroyItem(...) method:
public void destroyItem(View container, int position, Object object) {
super.destroyItem(container, position, object);
mPageReferences.remove(position);
}
... and when you need to access the currently visible page, you then call:
int index = mViewPager.getCurrentItem();
MyAdapter adapter = ((MyAdapter)mViewPager.getAdapter());
MyFragment fragment = adapter.getFragment(index);
... where the MyAdapter's getFragment(int) method looks like this:
public MyFragment getFragment(int key) {
return mPageReferences.get(key);
}
"
Okay, after testing the method by #barkside above, I could not get it to work with my application. Then I remembered that the IOSched2012 app uses a viewpager as well, and that is where I found my solution. It does not use any fragment ID's or Tags as these are not stored by viewpager in an easily accessible way.
Here's the important parts from the IOSched apps HomeActivity. Pay particular attention to the comment, as therein lies the key.:
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Since the pager fragments don't have known tags or IDs, the only way to persist the
// reference is to use putFragment/getFragment. Remember, we're not persisting the exact
// Fragment instance. This mechanism simply gives us a way to persist access to the
// 'current' fragment instance for the given fragment (which changes across orientation
// changes).
//
// The outcome of all this is that the "Refresh" menu button refreshes the stream across
// orientation changes.
if (mSocialStreamFragment != null) {
getSupportFragmentManager().putFragment(outState, "stream_fragment",
mSocialStreamFragment);
}
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
if (mSocialStreamFragment == null) {
mSocialStreamFragment = (SocialStreamFragment) getSupportFragmentManager()
.getFragment(savedInstanceState, "stream_fragment");
}
}
And store instances of you Fragments in the FragmentPagerAdapter like so:
private class HomePagerAdapter extends FragmentPagerAdapter {
public HomePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return (mMyScheduleFragment = new MyScheduleFragment());
case 1:
return (mExploreFragment = new ExploreFragment());
case 2:
return (mSocialStreamFragment = new SocialStreamFragment());
}
return null;
}
Also, remember to guard your Fragment calls like so:
if (mSocialStreamFragment != null) {
mSocialStreamFragment.refresh();
}
You can copy FragmentPagerAdapter and modify some source code, add getTag() method
for example
public abstract class AppFragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "FragmentPagerAdapter";
private static final boolean DEBUG = false;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private Fragment mCurrentPrimaryItem = null;
public AppFragmentPagerAdapter(FragmentManager fm) {
mFragmentManager = fm;
}
public abstract Fragment getItem(int position);
#Override
public void startUpdate(ViewGroup container) {
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
final long itemId = getItemId(position);
String name = getTag(position);
Fragment fragment = mFragmentManager.findFragmentByTag(name);
if (fragment != null) {
if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
mCurTransaction.attach(fragment);
} else {
fragment = getItem(position);
if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
mCurTransaction.add(container.getId(), fragment,
getTag(position));
}
if (fragment != mCurrentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Detaching item #" + getItemId(position) + ": f=" + object
+ " v=" + ((Fragment) object).getView());
mCurTransaction.detach((Fragment) object);
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
}
#Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
return null;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
public long getItemId(int position) {
return position;
}
private static String makeFragmentName(int viewId, long id) {
return "android:switcher:" + viewId + ":" + id;
}
protected abstract String getTag(int position);
}
then extend it, override these abstract method,don't need to be afraid of Android Group change
FragmentPageAdapter source code in the future
class TimeLinePagerAdapter extends AppFragmentPagerAdapter {
List<Fragment> list = new ArrayList<Fragment>();
public TimeLinePagerAdapter(FragmentManager fm) {
super(fm);
list.add(new FriendsTimeLineFragment());
list.add(new MentionsTimeLineFragment());
list.add(new CommentsTimeLineFragment());
}
public Fragment getItem(int position) {
return list.get(position);
}
#Override
protected String getTag(int position) {
List<String> tagList = new ArrayList<String>();
tagList.add(FriendsTimeLineFragment.class.getName());
tagList.add(MentionsTimeLineFragment.class.getName());
tagList.add(CommentsTimeLineFragment.class.getName());
return tagList.get(position);
}
#Override
public int getCount() {
return list.size();
}
}
Also works without problems:
somewhere in page fragment's layout:
<FrameLayout android:layout_width="0dp" android:layout_height="0dp" android:visibility="gone" android:id="#+id/fragment_reference">
<View android:layout_width="0dp" android:layout_height="0dp" android:visibility="gone"/>
</FrameLayout>
in fragment's onCreateView():
...
View root = inflater.inflate(R.layout.fragment_page, container, false);
ViewGroup ref = (ViewGroup)root.findViewById(R.id.fragment_reference);
ref.setTag(this);
ref.getChildAt(0).setTag("fragment:" + pageIndex);
return root;
and method to return Fragment from ViewPager, if exists:
public Fragment getFragment(int pageIndex) {
View w = mViewPager.findViewWithTag("fragment:" + pageIndex);
if (w == null) return null;
View r = (View) w.getParent();
return (Fragment) r.getTag();
}
Alternatively you can override setPrimaryItem method from FragmentPagerAdapter like so:
public void setPrimaryItem(ViewGroup container, int position, Object object) {
if (mCurrentFragment != object) {
mCurrentFragment = (Fragment) object; //Keep reference to object
((MyInterface)mCurrentFragment).viewDidAppear();//Or call a method on the fragment
}
super.setPrimaryItem(container, position, object);
}
public Fragment getCurrentFragment(){
return mCurrentFragment;
}
I want to give my approach in case it can help anyone else:
This is my pager adapter:
public class CustomPagerAdapter extends FragmentStatePagerAdapter{
private Fragment[] fragments;
public CustomPagerAdapter(FragmentManager fm) {
super(fm);
fragments = new Fragment[]{
new FragmentA(),
new FragmentB()
};
}
#Override
public Fragment getItem(int arg0) {
return fragments[arg0];
}
#Override
public int getCount() {
return fragments.length;
}
}
In my activity I have:
public class MainActivity {
private ViewPager view_pager;
private CustomPagerAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adapter = new CustomPagerAdapter(getSupportFragmentManager());
view_pager = (ViewPager) findViewById(R.id.pager);
view_pager.setAdapter(adapter);
view_pager.setOnPageChangeListener(this);
...
}
}
Then to get the current fragment what I do is:
int index = view_pager.getCurrentItem();
Fragment currentFragment = adapter.getItem(index);
This is my solution since I don't need to keep track of my tabs and need to refresh them all anyway.
Bundle b = new Bundle();
b.putInt(Constants.SharedPreferenceKeys.NUM_QUERY_DAYS,numQueryDays);
for(android.support.v4.app.Fragment f:getSupportFragmentManager().getFragments()){
if(f instanceof HomeTermFragment){
((HomeTermFragment) f).restartLoader(b);
}
}
I'm using FragmentPagerAdapter with FragmentActivity to create swipe-able Fragments.
My first fragment in that pagerAdapter look like this.
public class MySummaryFragment extends CommonFragment implements OnPageChangeListener
{
private Context mContext;
private View mMyView;
LinearLayout mDetailLayout;
TextView mDateTxtView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
System.out.println("onCreateView() Market summary");
mMyView = inflater.inflate(R.layout.my_page_summary_fragment_layout, container,false);
mDetailLayout = (LinearLayout)mMyView.findViewById(R.id.SummaryDetailLayout);
mDateTxtView = (TextView) mMyView.findViewById(R.id.txtDate);
Account_Id = AccountDetails.getInstance(mContext).getClientCodes().get(0);
sendRequest(Account_Id);
return mMyView;
}
#Override
public void onPageSelected(int arg0) {
System.out.println("inside onPageScrollStateChanged()");
System.out.println("mMyView is null ? = "+(mMyView==null));
mDateTxtView = (TextView) mMyView.findViewById(R.id.txtMarketSummaryDate);
Account_Id = AccountDetails.getInstance(mContext).getClientCodes().get(0);
mDateTxtView.setText("");
sendRequest(Account_Id);
}
}
The problem here is I'm getting NullPointerException when swipe-out to 5-6 fragments and swiping back to first fragment.
When I try to debug, I found that
mMyView is null ? = true
Why so?
Please help me.
Here is my Fragment contains the FragmentPagerAdapter,
public class MyPageDetailViewFragment extends CommonFragment {
private View mView;
Context mContext;
OnPageChangeListener pageChangeListener;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.my_page_fragments, null);
mContext = getActivity();
setHasOptionsMenu(false);
setupSearchBarComponent();
PagerTabStrip pagerTabStrip = (PagerTabStrip)mView. findViewById(R.id.pager_title_strip);
pagerTabStrip.setDrawFullUnderline(true);
pagerTabStrip.setTabIndicatorColor(Color.BLACK);
/** Getting a reference to the ViewPager defined the layout file */
ViewPager pager = (ViewPager) mView.findViewById(R.id.pager);
/** Getting fragment manager */
FragmentManager fm = ((HomeScreenActivity)mContext).getSupportFragmentManager();
/** Instantiating FragmentPagerAdapter */
final MyFragmentPagerAdapter pagerAdapter = new MyFragmentPagerAdapter(fm);
pager.setAdapter(pagerAdapter);
pager.setCurrentItem(0);
pageChangeListener = new OnPageChangeListener() {
#Override
public void onPageSelected(int selectedIndex) {
System.out.println("selectedIndex = "+selectedIndex);
Object page = pagerAdapter.getItem(selectedIndex);
if( page instanceof OnPageChangeListener){
((OnPageChangeListener) page).onPageSelected(selectedIndex);
}
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
};
pager.setOnPageChangeListener(pageChangeListener);
return mView;
// return super.onCreateView(inflater, container, savedInstanceState);
}
And here is my implementation MyFragmentPagerAdapter,
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
/** Constructor of the class */
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
/** This method will be invoked when a page is requested to create */
#Override
public Fragment getItem(int index) {
System.out.println("getItem = "+index);
Bundle data = new Bundle();
data.putInt("current_page", index + 1);
CommonFragment fragment = getFragment(index);
fragment.setArguments(data);
return fragment;
}
public CommonFragment getFragment(int index) {
CommonFragment fragment = null;
if(fragment == null){
if(index == 0){
fragment = new MySummaryFragment();
}else if(index == 1){
fragment = new FragmentOne();
}else if(index == 4){
fragment = new FragmentFour();
}else if(index == 5){
fragment = new FragmentFive();
}else{
fragment = new MyFragment();
}
}
return fragment;
}
/** Returns the number of pages */
#Override
public int getCount() {
return titles.length;
}
#Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
}
pagerAdapter.getItem(selectedIndex) actually creates a new instance of the fragment.
See this answer: https://stackoverflow.com/a/23843743/1271907
You have to keep a reference to the actual fragment.
It looks like you are calling the wrong method on the inflater.
Try to change this line:
mView = inflater.inflate(R.layout.my_page_fragments, null);
to:
mView = inflater.inflate(R.layout.my_page_fragments,container, null);