Remove Fragment Page from ViewPager in Android

Question

I m trying to dynamically add and remove Fragments from a ViewPager  adding works without any problems  but removing doesn t work as expected   Everytime I want to remove the current item  the last one gets removed   I also tried to use an FragmentStatePagerAdapter or return POSITION NONE in the adapter s getItemPosition method   What am I doing wrong   Here s a basic example   MainActivity java  public class MainActivity extends FragmentActivity implements TextProvider        private Button mAdd      private Button mRemove      private ViewPager mPager       private MyPagerAdapter mAdapter       private ArrayList lt String gt  mEntries   new ArrayList lt String gt           Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main            mEntries add  pos 1            mEntries add  pos 2            mEntries add  pos 3            mEntries add  pos 4            mEntries add  pos 5             mAdd    Button  findViewById R id add           mRemove    Button  findViewById R id remove           mPager    ViewPager  findViewById R id pager            mAdd setOnClickListener new OnClickListener                  Override             public void onClick View view                    addNewItem                                       mRemove setOnClickListener new OnClickListener                  Override             public void onClick View view                    removeCurrentItem                                       mAdapter   new MyPagerAdapter this getSupportFragmentManager    this            mPager setAdapter mAdapter               private void addNewItem             mEntries add  new item            mAdapter notifyDataSetChanged               private void removeCurrentItem             int position   mPager getCurrentItem            mEntries remove position           mAdapter notifyDataSetChanged                Override     public String getTextForPosition int position            return mEntries get position              Override     public int getCount             return mEntries size                private class MyPagerAdapter extends FragmentPagerAdapter            private TextProvider mProvider           public MyPagerAdapter FragmentManager fm  TextProvider provider                super fm               this mProvider   provider                      Override         public Fragment getItem int position                return MyFragment newInstance mProvider getTextForPosition position                        Override         public int getCount                 return mProvider getCount                          TextProvider java  public interface TextProvider       public String getTextForPosition int position       public int getCount        MyFragment java  public class MyFragment extends Fragment        private String mText       public static MyFragment newInstance String text            MyFragment f   new MyFragment text           return f             public MyFragment                public MyFragment String text            this mText   text              Override     public View onCreateView LayoutInflater inflater  ViewGroup container              Bundle savedInstanceState             View root   inflater inflate R layout fragment  container  false              TextView  root findViewById R id position   setText mText            return root             activity main xml   lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android      android layout width  match parent      android layout height  match parent      android orientation  vertical   gt        lt Button         android id    id add          android layout width  match parent          android layout height  wrap content          android text  add new item    gt        lt Button         android id    id remove          android layout width  match parent          android layout height  wrap content          android text  remove current item    gt        lt android support v4 view ViewPager         android id    id pager          android layout width  match parent          android layout height  0dip          android layout weight  1    gt    lt  LinearLayout gt    fragment xml   lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android      android layout width  match parent      android layout height  match parent      android orientation  vertical   gt        lt TextView         android id    id position          android layout width  match parent          android layout height  match parent          android gravity  center          android textSize  35sp    gt    lt  LinearLayout gt

User · Answer

2020 now  Simple add this to PageAdapter  override fun getItemPosition  object   Any   Int       return PagerAdapter POSITION NONE

User · Answer

Louth s answer works fine  But I don t think always return POSITION NONE is a good idea  Because POSITION NONE means that fragment should be destroyed and a new fragment will be created  You can check that in dataSetChanged function in the source code of ViewPager           if  newPos    PagerAdapter POSITION NONE                mItems remove i               i--                  not related code             mAdapter destroyItem this  ii position  ii object     So I think you d better use an arraylist of weakReference to save all the fragments you have created  And when you add or remove some page  you can get the right position from your own arraylist    public int getItemPosition Object object        for  int i   0  i  lt  mFragmentsReferences size    i               WeakReference lt Fragment gt  reference   mFragmentsReferences get i           if  reference    null  amp  amp  reference get      null                Fragment fragment   reference get                if  fragment    object                    return i                                    return POSITION NONE      According to the comments  getItemPosition is Called when the host view is attempting to determine if an item s position has changed  And the return value means its new position    But this is not enought  We still have an important step to take  In the source code of FragmentStatePagerAdapter  there is an array named  mFragments  caches the fragments which are not destroyed  And in instantiateItem function   if  mFragments size    gt  position            Fragment f   mFragments get position           if  f    null                return f                    It returned the cached fragment directly when it find that cached fragment is not null  So there is a problem  From example  let s delete one page at position 2  Firstly  We remove that fragment from our own reference arraylist  so in getItemPosition it will return POSITION NONE for that fragment  and then that fragment will be destroyed and removed from  mFragments     mFragments set position  null     Now the fragment at position 3 will be at position 2  And instantiatedItem with param position 3 will be called  At this time  the third item in  mFramgents  is not null  so it will return directly  But actually what it returned is the fragment at position 2  So when we turn into page 3  we will find an empty page there   To work around this problem  My advise is that you can copy the source code of FragmentStatePagerAdapter into your own project  and when you do add or remove operations  you should add and remove elements in the  mFragments  arraylist   Things will be simpler if you just use PagerAdapter instead of FragmentStatePagerAdapter  Good Luck

User · Answer

I hope this can help what you want   private class MyPagerAdapter extends FragmentStatePagerAdapter              your existing code       Override     public int getItemPosition Object object           return PagerAdapter POSITION UNCHANGED

User · Answer

The solution by Louth was not enough to get things working for me  as the existing fragments were not getting destroyed  Motivated by this answer  I found that the solution is to override the getItemId int position  method of FragmentPagerAdapter to give a new unique ID whenever there has been a change in the expected position of a Fragment   Source Code   private class MyPagerAdapter extends FragmentPagerAdapter        private TextProvider mProvider      private long baseId   0       public MyPagerAdapter FragmentManager fm  TextProvider provider            super fm           this mProvider   provider              Override     public Fragment getItem int position            return MyFragment newInstance mProvider getTextForPosition position                Override     public int getCount             return mProvider getCount                  this is called when notifyDataSetChanged   is called      Override     public int getItemPosition Object object               refresh all fragments when data set changed         return PagerAdapter POSITION NONE               Override     public long getItemId int position               give an ID different from position when position has been changed         return baseId   position                        Notify that the position of a fragment has been changed         Create a new ID for each position to force recreation of the fragment         param n number of items which have been changed             public void notifyChangeInPosition int n               shift the ID returned by getItemId outside the range of all previous fragments         baseId    getCount     n            Now  for example if you delete a single tab or make some change to the order  you should call notifyChangeInPosition 1  before calling notifyDataSetChanged    which will ensure that all the Fragments will be recreated   Why this solution works  Overriding getItemPosition     When notifyDataSetChanged   is called  the adapter calls the notifyChanged   method of the ViewPager which it is attached to  The ViewPager then checks the value returned by the adapter s getItemPosition   for each item  removing those items which return POSITION NONE  see the source code  and then repopulating    Overriding getItemId     This is necessary to prevent the adapter from reloading the old fragment when the ViewPager is repopulating  You can easily understand why this works by looking at the source code for instantiateItem   in FragmentPagerAdapter       final long itemId   getItemId position           Do we already have this fragment      String name   makeFragmentName container getId    itemId       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                  makeFragmentName container getId    itemId            As you can see  the getItem   method is only called if the fragment manager finds no existing fragments with the same Id  To me it seems like a bug that the old fragments are still attached even after notifyDataSetChanged   is called  but the documentation for ViewPager does clearly state that      Note this class is currently under early design and development  The API will likely change in later updates of the compatibility library  requiring changes to the source code of apps when they are compiled against the newer version    So hopefully the workaround given here will not be necessary in a future version of the support library

User · Answer

My final version code  fixed ALL bugs  It took me 3 days Updated 2020 07 18  I had changed a lot of the source code and fix so many bugs  but I don t promise it still work today  https   github com lin1987www FragmentBuilder blob master commonLibrary src main java android support v4 app FragmentStatePagerAdapterFix java public class FragmentStatePagerAdapterFix extends PagerAdapter       private static final String TAG   FragmentStatePagerAdapterFix class getSimpleName        private static final boolean DEBUG   false       private WeakReference lt FragmentActivity gt  wrFragmentActivity      private WeakReference lt Fragment gt  wrParentFragment      private final FragmentManager mFragmentManager      private FragmentTransaction mCurTransaction   null       protected ArrayList lt Fragment gt  mFragments   new ArrayList lt  gt         protected ArrayList lt FragmentState gt  mFragmentStates   new ArrayList lt  gt         protected ArrayList lt String gt  mFragmentTags   new ArrayList lt  gt         protected ArrayList lt String gt  mFragmentClassNames   new ArrayList lt  gt         protected ArrayList lt Bundle gt  mFragmentArgs   new ArrayList lt  gt          private Fragment mCurrentPrimaryItem   null      private boolean   mTempPositionChange        Override     public int getCount             return mFragmentClassNames size               public FragmentActivity getFragmentActivity             return wrFragmentActivity get               public Fragment getParentFragment             return wrParentFragment get               public FragmentStatePagerAdapterFix FragmentActivity activity            mFragmentManager   activity getSupportFragmentManager            wrFragmentActivity   new WeakReference lt  gt  activity           wrParentFragment   new WeakReference lt  gt  null              public FragmentStatePagerAdapterFix Fragment fragment            mFragmentManager   fragment getChildFragmentManager            wrFragmentActivity   new WeakReference lt  gt  fragment getActivity             wrParentFragment   new WeakReference lt  gt  fragment              public void add Class lt   extends android support v4 app Fragment gt  fragClass            add fragClass  null  null              public void add Class lt   extends android support v4 app Fragment gt  fragClass  Bundle args            add fragClass  args  null              public void add Class lt   extends android support v4 app Fragment gt  fragClass  String tag            add fragClass  null  tag              public void add Class lt   extends android support v4 app Fragment gt  fragClass  Bundle args  String tag            add fragClass  args  tag  getCount                public void add Class lt   extends android support v4 app Fragment gt  fragClass  Bundle args  String tag  int position            mFragments add position  null           mFragmentStates add position  null           mFragmentTags add position  tag           mFragmentClassNames add position  fragClass getName             mFragmentArgs add position  args           mTempPositionChange   new boolean getCount                public void remove int position            if  position  lt  getCount                  mTempPositionChange   new boolean getCount                 for  int i   position  i  lt  mTempPositionChange length  i                      mTempPositionChange i    true                            mFragments remove position               mFragmentStates remove position               mFragmentTags remove position               mFragmentClassNames remove position               mFragmentArgs remove position                        public void clear            mFragments clear            mFragmentStates clear            mFragmentTags clear            mFragmentClassNames clear            mFragmentArgs clear                Override     public void startUpdate ViewGroup container                Override     public Object instantiateItem ViewGroup container  int position            Fragment fragment             If we already have this item instantiated  there is nothing            to do   This can happen when we are restoring the entire pager            from its saved state  where the fragment manager has already            taken care of restoring the fragments we previously had instantiated          fragment   mFragments get position           if  fragment    null                return fragment                    if  mCurTransaction    null                mCurTransaction   mFragmentManager beginTransaction                      FragmentState fs   mFragmentStates get position           if  fs    null                fragment   fs instantiate getFragmentActivity    getParentFragment                    Fix bug                http   stackoverflow com questions 11381470 classnotfoundexception-when-unmarshalling-android-support-v4-view-viewpagersav             if  fragment mSavedFragmentState    null                    fragment mSavedFragmentState setClassLoader fragment getClass   getClassLoader                                     if  fragment    null                fragment   Fragment instantiate getFragmentActivity    mFragmentClassNames get position   mFragmentArgs get position                      if  DEBUG                Log v TAG   quot Adding item   quot    position    quot   f  quot    fragment                     fragment setMenuVisibility false           fragment setUserVisibleHint false           mFragments set position  fragment           mFragmentStates set position  null           mCurTransaction add container getId    fragment  mFragmentTags get position            return fragment              Override     public void destroyItem ViewGroup container  int position  Object object            Fragment fragment    Fragment  object          if  mCurTransaction    null                mCurTransaction   mFragmentManager beginTransaction                      if  DEBUG                Log v TAG   quot Removing item   quot    position    quot   f  quot    object                        quot  v  quot      Fragment  object  getView                       if  position  lt  getCount                  FragmentState fragmentState   new FragmentState fragment               Fragment SavedState savedState   mFragmentManager saveFragmentInstanceState fragment               if  savedState    null                    fragmentState mSavedFragmentState   savedState mState                            mFragmentStates set position  fragmentState               mFragments set position  null                     mCurTransaction remove fragment               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                   Fix  Fragment is added by transaction  BUT didn t add to FragmentManager s mActive              for  Fragment fragment   mFragments                    if  fragment    null                        fixActiveFragment mFragmentManager  fragment                                                         Override     public boolean isViewFromObject View view  Object object            return   Fragment  object  getView      view              Override     public Parcelable saveState             Bundle state   null                   Fragments         for  int i   0  i  lt  mFragments size    i                  Fragment f   mFragments get i               if  f    null  amp  amp  f isAdded                      if  state    null                        state   new Bundle                                      String key    quot f quot    i                  mFragmentManager putFragment state  key  f                                   if  mFragmentStates size    gt  0                if  state    null                    state   new Bundle                              FragmentState   fs   new FragmentState mFragmentStates size                 mFragmentStates toArray fs               state putParcelableArray  quot states fragment quot   fs                     return state              Override     public void restoreState Parcelable state  ClassLoader loader            if  state    null                Bundle bundle    Bundle  state              bundle setClassLoader loader               Parcelable   fs   bundle getParcelableArray  quot states fragment quot                mFragments clear                mFragmentStates clear                mFragmentTags clear                mFragmentClassNames clear                mFragmentArgs clear                if  fs    null                    for  int i   0  i  lt  fs length  i                          FragmentState fragmentState    FragmentState  fs i                       mFragmentStates add fragmentState                       if  fragmentState    null                            mFragmentArgs add fragmentState mArguments                           mFragmentTags add fragmentState mTag                           mFragmentClassNames add fragmentState mClassName                         else                           mFragmentArgs add null                           mFragmentTags add null                           mFragmentClassNames add null                                             mFragments add null                                               Iterable lt String gt  keys   bundle keySet                for  String key   keys                    if  key startsWith  quot f quot                          int index   Integer parseInt key substring 1                        Fragment f   mFragmentManager getFragment bundle  key                       if  f    null                            f setMenuVisibility false                           mFragments set index  f                           mFragmentArgs set index  f mArguments                           mFragmentTags set index  f mTag                           mFragmentClassNames set index  f getClass   getName                           else                           Log w TAG   quot Bad fragment at key  quot    key                                                                        If restore will change             notifyDataSetChanged                         public static void fixActiveFragment FragmentManager fragmentManager  Fragment fragment            FragmentManagerImpl fm    FragmentManagerImpl  fragmentManager          if  fm mActive    null                int index   fragment mIndex              Fragment origin   fm mActive get index               if  origin    null                    if   origin mIndex    fragment mIndex       origin equals fragment                          Log e TAG                              String format  quot fixActiveFragment  Not Equal  Origin   s  s  Fragment   s  s quot                                       origin getClass   getName    origin mIndex                                      fragment getClass   getName    fragment mIndex                                                                             fm mActive set index  fragment                           Fix        http   stackoverflow com questions 10396321 remove-fragment-page-from-viewpager-in-android      Override     public int getItemPosition Object object            int index   mFragments indexOf object           if  index  lt  0                return PagerAdapter POSITION NONE                    boolean isPositionChange   mTempPositionChange index           int result   PagerAdapter POSITION UNCHANGED          if  isPositionChange                result   PagerAdapter POSITION NONE                    return result

User · Answer

I added a function  clearFragments  and I used that function to clear adapter before setting the new fragments  This calls the proper remove actions of Fragments  My pagerAdapter class   private class ChartPagerAdapter extends FragmentPagerAdapter      private ArrayList lt Fragment gt  fragmentList       ChartPagerAdapter FragmentManager fm           super fm           fragmentList   new ArrayList lt  gt                void setFragments ArrayList lt   extends Fragment gt  fragments           fragmentList addAll fragments              void clearFragments            for Fragment fragment fragmentList              getChildFragmentManager   beginTransaction   remove fragment  commit            fragmentList clear                Override     public Fragment getItem int i            return fragmentList get i               Override     public int getCount             return fragmentList size

User · Answer

The fragment must be already removed but the issue was viewpager save state  Try  myViewPager setSaveFromParentEnabled false     Nothing worked but this solved the issue    Cheers

User · Answer

Try this solution  I have used databinding for binding view  You can use common  findViewById    function   public class ActCPExpense extends BaseActivity implements View OnClickListener     private static final String TAG   ActCPExpense class getSimpleName    private Context mContext  private ActCpLossBinding mBinding   private ViewPagerAdapter adapter      Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       try           setContentView R layout act cp loss           mBinding   DataBindingUtil setContentView this  R layout act cp loss           mContext   ActCPExpense this          initViewsAct            catch  Exception e            LogUtils LOGE TAG  e              private void initViewsAct          adapter   new ViewPagerAdapter getSupportFragmentManager         adapter addFragment FragmentCPPayee newInstance     Title        mBinding viewpager setAdapter adapter       mBinding tab setViewPager mBinding viewpager            Override public boolean onOptionsItemSelected MenuItem itemActUtility        int i   itemActUtility getItemId        if  i    android R id home            onBackPressed                 return super onOptionsItemSelected itemActUtility       Override public void onClick View view        super onClick view       int id   view getId        if  id    R id btnAdd            addFragment           else if  id    R id btnDelete            removeFragment                   private void addFragment        adapter addFragment FragmentCPPayee newInstance  Title        adapter notifyDataSetChanged        mBinding tab setViewPager mBinding viewpager     private void removeFragment        adapter removeItem mBinding viewpager getCurrentItem         mBinding tab setViewPager mBinding viewpager       class ViewPagerAdapter extends FragmentStatePagerAdapter       private final List lt Fragment gt  mFragmentList   new ArrayList lt  gt         private final List lt String gt  mFragmentTitleList   new ArrayList lt  gt           public ViewPagerAdapter FragmentManager manager            super manager               Override     public int getItemPosition  NonNull Object object            return PagerAdapter POSITION NONE               Override     public Fragment getItem int position            return mFragmentList get position               Override     public int getCount             return mFragmentList size                public void addFragment Fragment fragment  String title            mFragmentList add fragment           mFragmentTitleList add title               public void removeItem int pos             destroyItem null  pos  mFragmentList get pos            mFragmentList remove pos           mFragmentTitleList remove pos           adapter notifyDataSetChanged            mBinding viewpager setCurrentItem pos - 1  false               Override     public CharSequence getPageTitle int position            return  Title     String valueOf position   1

User · Answer

You could just override the destroyItem method   Override public void destroyItem ViewGroup container  int position  Object object        fragmentManager beginTransaction   remove  Fragment  object  commitNowAllowingStateLoss

User · Answer

add or remove fragment in viewpager dynamically    Call setupViewPager viewPager  on activity start    To load different fragment call setupViewPagerCustom viewPager     e g  on button click call  setupViewPagerCustom viewPager         private void setupViewPager ViewPager viewPager        ViewPagerAdapter adapter   new ViewPagerAdapter getSupportFragmentManager         adapter addFrag new fragmnet1     HOME        adapter addFrag new fragmnet2     SERVICES         viewPager setAdapter adapter      private void setupViewPagerCustom ViewPager viewPager         ViewPagerAdapter adapter   new ViewPagerAdapter getSupportFragmentManager          adapter addFrag new fragmnet3     Contact us        adapter addFrag new fragmnet4     ABOUT US          viewPager setAdapter adapter        Viewpageradapter  handles the views  static class ViewPagerAdapter extends FragmentStatePagerAdapter       private final List lt Fragment gt  mFragmentList   new ArrayList lt  gt         private final List lt String gt  mFragmentTitleList   new ArrayList lt  gt          public ViewPagerAdapter FragmentManager manager           super manager               Override     public Fragment getItem int position            return mFragmentList get position               Override     public int getCount             return mFragmentList size                Override     public int getItemPosition Object object           return PagerAdapter POSITION NONE             public void addFrag Fragment fragment  String title           mFragmentList add fragment           mFragmentTitleList add title               Override     public CharSequence getPageTitle int position           return mFragmentTitleList get position

User · Answer

i solved this problem by these steps  1- use FragmentPagerAdapter  2- in each fragment create a random id  fragment id   new Random   nextInt      3- override getItemPosition in adapter   Override public int getItemPosition  NonNull Object object        return PagerAdapter POSITION NONE      4-override getItemId in adapter    Override public long getItemId int position        return mDatasetFragments get position  id      5- now delete code is   adapter mDatasetFragments remove  lt  item to delete position  gt     adapter notifyDataSetChanged      this worked for me i hope help

User · Answer

I had the idea of simply copy the source code from android support v4 app FragmentPagerAdpater into a custom class named  CustumFragmentPagerAdapter  This gave me the chance to modify the instantiateItem      so that every time it is called  it removes   destroys the currently attached fragment before it adds the new fragment received from getItem   method   Simply modify the instantiateItem      in the following way    Override public Object instantiateItem ViewGroup container  int position        if  mCurTransaction    null            mCurTransaction   mFragmentManager beginTransaction              final long itemId   getItemId position           Do we already have this fragment      String name   makeFragmentName container getId    itemId       Fragment fragment   mFragmentManager findFragmentByTag name           remove   destroy current fragment     if  fragment    null            mCurTransaction remove fragment                 get new fragment and add it     fragment   getItem position       mCurTransaction add container getId    fragment     makeFragmentName container getId    itemId         if  fragment    mCurrentPrimaryItem            fragment setMenuVisibility false           fragment setUserVisibleHint false              return fragment

User · Answer

my working solution to remove fragment page from view pager  public class MyFragmentAdapter extends FragmentStatePagerAdapter        private ArrayList lt ItemFragment gt  pages       public MyFragmentAdapter FragmentManager fragmentManager  ArrayList lt ItemFragment gt  pages            super fragmentManager           this pages   pages              Override     public Fragment getItem int index            return pages get index               Override     public int getCount             return pages size                Override     public int getItemPosition Object object            int index   pages indexOf  object            if  index    -1              return POSITION NONE          else             return index            And when i need to remove some page by index i do this  pages remove position      ArrayList lt ItemFragment gt  adapter notifyDataSetChanged       MyFragmentAdapter   Here it is my adapter initialization  MyFragmentAdapter adapter   new MyFragmentAdapter getSupportFragmentManager    pages   viewPager setAdapter adapter

User · Answer

I had some problems with FragmentStatePagerAdapter  After removing an item    there was another item used for a position  an item which did not belong to the position but to a position next to it  or some fragment was not loaded  there was only blank background visible on that page    After lots of experiments  I came up with the following solution   public class SomeAdapter extends FragmentStatePagerAdapter        private List lt Item gt  items   new ArrayList lt Item gt          private boolean removing        Override     public Fragment getItem int position            ItemFragment fragment   new ItemFragment            Bundle args   new Bundle               use items get position  to configure fragment         fragment setArguments args           return fragment              Override     public int getCount             return items size                Override     public int getItemPosition Object object            if  removing                return PagerAdapter POSITION NONE                     Item item   getItemOfFragment object            int index   items indexOf item           if  index    -1                return POSITION NONE            else               return index                      public void addItem Item item            items add item           notifyDataSetChanged               public void removeItem int position            items remove position            removing   true          notifyDataSetChanged            removing   false            This solution only uses a hack in case of removing an item  Otherwise  e g  when adding an item  it retains the cleanliness and performance of an original code   Of course  from the outside of the adapter  you call only addItem removeItem  no need to call notifyDataSetChanged

User · Answer

You can combine both for better     private class MyPagerAdapter extends FragmentStatePagerAdapter              your existing code       Override     public int getItemPosition Object object          if Any Reason You WantTo Update Positions    this includes deleting or adding pages  return PagerAdapter POSITION NONE        else return PagerAdapter POSITION UNCHANGED    this ensures high performance in other operations such as editing list items

User · Answer

The ViewPager doesn t remove your fragments with the code above because it loads several views   or fragments in your case  into memory  In addition to the visible view  it also loads the view to either side of the visible one  This provides the smooth scrolling from view to view that makes the ViewPager so cool   To achieve the effect you want  you need to do a couple of things     Change the FragmentPagerAdapter to a FragmentStatePagerAdapter  The reason for this is that the FragmentPagerAdapter will keep all the views that it loads into memory forever  Where the FragmentStatePagerAdapter disposes of views that fall outside the current and traversable views  Override the adapter method getItemPosition  shown below   When we call mAdapter notifyDataSetChanged    the ViewPager interrogates the adapter to determine what has changed in terms of positioning  We use this method to say that everything has changed so reprocess all your view positioning       And here s the code     private class MyPagerAdapter extends FragmentStatePagerAdapter              your existing code       Override     public int getItemPosition Object object           return PagerAdapter POSITION NONE

User · Answer

For future readers   Now you can use ViewPager2 for dynamically adding  removing fragment from the viewpager   Quoting form API reference      ViewPager2 replaces ViewPager  addressing most of its predecessor   s   pain-points  including right-to-left layout support  vertical   orientation  modifiable Fragment collections  etc    Take look at MutableCollectionFragmentActivity kt in googlesample android-viewpager2 for an example of adding  removing fragments dynamically from the viewpager     For your information   Articles     Exploring the ViewPager2 Look deep into ViewPager2   API reference  Release notes  Samples Repo  https   github com googlesamples android-viewpager2

[android] Remove Fragment Page from ViewPager in Android

Examples related to android

Examples related to android-viewpager

Examples related to fragmentpageradapter