Update Fragment from ViewPager

Question

I have an Activity with a ViewPager  I also have a Dialog that will retrieve a list with some items that the user will choose  Now  how can I update the Fragment where the Items are supposed to display as new views attached to this Fragment    Here is my ViewPager s adapter   public static class MyAdapter extends FragmentPagerAdapter       public MyAdapter FragmentManager fm            super fm               Override     public int getCount             return 1              Override     public android support v4 app Fragment getItem int position            switch  position            case 0              return new Fragment1             default              return null                      Now  here is the Fragment   public class Fragment1 extends Fragment    Override public void onActivityCreated Bundle savedInstanceState           TODO Auto-generated method stub     super onActivityCreated savedInstanceState       Override public void onCreate Bundle savedInstanceState           TODO Auto-generated method stub     super onCreate savedInstanceState       Override public ViewGroup onCreateView LayoutInflater inflater  ViewGroup container          Bundle savedInstanceState           TODO Auto-generated method stub     ViewGroup view    ViewGroup inflater inflate R layout screen1  container  false             return view         This is the method that I want to use to add Items to my Fragment  private void addItem             Instantiate a new  row  view       final ViewGroup   newViews   new ViewGroup selectedItems length         for int i   0  i  lt  selectedItems length  i             newViews i     ViewGroup  LayoutInflater from this  inflate                      R layout animated layout item  mContainerView  false               Set the text in each new row            TextView  newViews i  findViewById android R id text1   setText selectedItems i                Because mContainerView has android animateLayoutChanges set to true             adding this view is automatically animated               mContainerView addView newViews i   0                Set a click listener for the  X  button in the row that will remove the row          OnClickListener listener   new MyAddItemListener newViews i   mContainerView  this           newViews i  findViewById R id delete button  setOnClickListener listener

User · Answer

1  Create a handler in the fragment that you want to update   public static Handler sUpdateHandler    Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState                         sUpdateHandler   new Handler                 Override             public void handleMessage Message msg                    super handleMessage msg                      call you update method here                                   2  In the Activity Fragment Dialog  wherever you want the update call to be fired  get the reference to that handler and send a message  telling your fragment to update      Check if the fragment is visible by checking if the handler is null or not  Handler handler   TaskTabCompletedFragment sUpdateHandler  if  handler    null        handler obtainMessage   sendToTarget

User · Answer

Update Fragment from ViewPager   You need to implement getItemPosition Object obj  method   This method is called when you call  notifyDataSetChanged     on your ViewPagerAdaper  Implicitly this method returns POSITION UNCHANGED value that means something like this   Fragment is where it should be so don t change anything    So if you need to update Fragment you can do it with    Always return POSITION NONE from getItemPosition   method  It which means   Fragment must be always recreated  You can create some update   method that will update your Fragment fragment will handle updates itself      Example of second approach   public interface Updateable      public void update        public class MyFragment extends Fragment implements Updateable               public void update             do your stuff          And in FragmentPagerAdapter you ll do something like this    Override public int getItemPosition Object object       MyFragment f    MyFragment   object     if  f    null          f update           return super getItemPosition object       And if you ll choose first approach it can looks like    Override public int getItemPosition Object object       return POSITION NONE      Note  It s worth to think a about which approach you ll pick up

User · Answer

Because none of the above answers did the trick for me  here is my solution   I combined the POSITION NONE with loading on setUserVisibleHint boolean isVisibleToUser  instead of onStart    As seen here  https   stackoverflow com a 25676323 497366  In the Fragment    Override public void setUserVisibleHint boolean isVisibleToUser        super setUserVisibleHint isVisibleToUser       if  isVisibleToUser               load data here      else            fragment is no longer visible           and in the FragmentStatePagerAdapter as seen in the top answer here from Simon Dorociak https   stackoverflow com a 18088509 497366    Override public int getItemPosition  NonNull Object object        return POSITION NONE      Now the fragments reload the data into their views everytime they are shown to the user

User · Answer

Accepted answer is not understand  That s why added easy solution  after long struggle  find Working solution   Just notify to your adapter  it s working amazing      Reference code    void setAdapter int position            PagerAdapter pagerAdapter   new PagerAdapter getSupportFragmentManager             viewPager setAdapter pagerAdapter              when notify then set manually current position          viewPager setCurrentItem position           pagerAdapter notifyDataSetChanged               call this code when you set adapter and when you want to refresh UI    In Your fragment add this code for refresh    YourActivityName  getContext    setAdapter selectedTabPosition     Use instanceof for cast context   This code share only helping purpose who find solution

User · Answer

If you use Kotlin  you can do the following   1  On first  you should be create Interface and implemented him in your Fragment  interface RefreshData       fun refresh      class YourFragment   Fragment    RefreshData               override fun refresh               do what you want           2  Next step is add OnPageChangeListener to your ViewPager  viewPager addOnPageChangeListener object   ViewPager OnPageChangeListener       override fun onPageScrollStateChanged state  Int           override fun onPageSelected position  Int            viewPagerAdapter notifyDataSetChanged           viewPager currentItem   position            override fun onPageScrolled position  Int  positionOffset  Float  positionOffsetPixels  Int           3  override getItemPosition in your Adapter  override fun getItemPosition obj  Any   Int       if  obj is RefreshData            obj refresh             return super getItemPosition obj

User · Answer

You can update the fragment in two different ways  First way like  Sajmon You need to implement getItemPosition Object obj  method  This method is called when you call notifyDataSetChanged    You can find a example in Github and more information in this post   Second way My approach to update fragments within the viewpager is to use the setTag   method for any instantiated view in the instantiateItem   method  So when you want to change the data or invalidate the view that you need  you can call the findViewWithTag   method on the ViewPager to retrieve the previously instantiated view and modify use it as you want without having to delete create a new view each time you want to update some value   Override public Object instantiateItem ViewGroup container  int position        Object object   super instantiateItem container  position       if  object instanceof Fragment            Fragment fragment    Fragment  object          String tag   fragment getTag            mFragmentTags put position  tag             return object     public Fragment getFragment int position        Fragment fragment   null      String tag   mFragmentTags get position       if  tag    null            fragment   mFragmentManager findFragmentByTag tag             return fragment     You can find a example in Github or more information in this post

User · Answer

A very simple yet effective solution to update your fragment views  Use setUserVisibleHint   method  It will be called upon when the fragment is about to be visible to user  There you can update our view  setText   or setVisibility   etc      Override public void setUserVisibleHint boolean isVisibleToUser        super setUserVisibleHint isVisibleToUser        if isVisibleToUser            Write your code to be executed when it is visible to user           It worked in my case  Hope it helps

User · Answer

I faced problem some times so that in this case always avoid FragmentPagerAdapter and use FragmentStatePagerAdapter    It work for me  I hope it will work for you also

User · Answer

In your PagerAdapter override getItemPosition   Override public int getItemPosition Object object       POSITION NONE makes it possible to reload the PagerAdapter return POSITION NONE      After that add viewPager getAdapter   notifyDataSetChanged    this code like below  viewPager addOnPageChangeListener new ViewPager OnPageChangeListener              Override         public void onPageScrolled int position  float positionOffset  int positionOffsetPixels                         Override         public void onPageSelected int position                viewPager getAdapter   notifyDataSetChanged                        Override         public void onPageScrollStateChanged int state                         should work

User · Answer

Maybe your method for adding items into fragment should be public  placed in desired Fragment  and should have parameter the same type as selectedItems      That will make it visible from activity  which will have selectedItems array and voila     p s  better name it addItemsFromArray typeOfSelectedItems   pSelectedItems  cause name addItem   is quite undescriptive    Edit  stackoverflow just suggested similar topic    Check here for detailed idea implementation

User · Answer

I implement a app demo following Sajmon s answer  Just for anyone else who search this question   You can access source code on GitHub

User · Answer

i had 4 Fragments in the ViewPager  but i wanted to update just one Fragment   FavoriteFragment  at the position 0 of the viewPager  every time the user click on this fragment  but none of the codes above helped me reload just the one Fragment i want   so i tried this and it works for me   in my FavoriteFragment i overrided onResume     Override     public void onResume             super onResume            updateUI       code to update the UI in the fragment         in the Activity hosting the viewPager override addOnPageChangeListener   and add this code  mViewPager addOnPageChangeListener new ViewPager SimpleOnPageChangeListener                  Override             public void onPageSelected int position                    super onPageSelected position                    if position    0       0   the first fragment in the ViewPager  in this case  the fragment i want to refresh its UI                     FavoritesFragment fragment    FavoritesFragment  mViewPager getAdapter   instantiateItem mViewPager  position                        fragment onResume       here i call the onResume of the fragment  where i have the method updateUI   to update its UI                     mViewPager getAdapter   notifyDataSetChanged                                                  and it works perfect for me  to refresh reload just the one fragment i want

User · Answer

Very simple to override the method in the fragment    Override  public void setUserVisibleHint boolean isVisibleToUser        super setUserVisibleHint isVisibleToUser        if isVisibleToUser           actionView              else            no

[android] Update Fragment from ViewPager

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