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Can't change the tabItem ( program crashes ), when I delete one of my tabItems with code

I have an application in which I create TabItems dynamically and I add them to the TabLayout. I'll show you the code below. then I also have a mechanism that when a tabitem is created, the user can close it with a click of a button. NOW: the problem happens here. when the user deletes that tabitem and program automatically directs the user to another tab. I can no longer click on the other tabs that I created at the start of the application. I Can click on them, but the program closes with the error
java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 4, found: 3 Pager
and all of this happens when I delete a tabitem with a code written for a click. below is my MainActivity.java code :
public class MainActivity extends AppCompatActivity implements ContactsFragment.CallBacks, UserDetailFragment.DetailCallBacks {
android.support.v7.widget.Toolbar toolbar;
public static List<Fragment> fragments = new ArrayList<>();
public static List<String> fragmentsTitle = new ArrayList<>();
ViewPager viewPager;
TabLayout tabLayout;
int tabposition_number;
public List<Fragment> getFragments() {
return fragments;
}
public List<String> getFragmentsTitle() {
return fragmentsTitle;
}
public void addToFragments(Fragment fragment) {
fragments.add(fragment);
}
public void addToFragmentsTitle(String title) {
fragmentsTitle.add(title);
}
public Fragment getFragmentsWithPosition(int position) {
return fragments.get(position);
}
public String getFragmentsTitleWithPosition(int position) {
return fragmentsTitle.get(position);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater menuInflater = new MenuInflater(this);
menuInflater.inflate(R.menu.top_main_menu,menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId() == R.id.remove_tab) {
remove_tab_details(3);
}
return super.onOptionsItemSelected(item);
}
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_page_drawer);
this.tabLayout = findViewById(R.id.tab_layout);
this.viewPager = findViewById(R.id.view_pager);
tabLayout.setupWithViewPager(viewPager);
SetUpViewPager(viewPager);
this.toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
NavigationView navigationView = findViewById(R.id.navigation_view);
navigationView.setItemIconTintList(null);
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener(){
#Override
public void onTabSelected(TabLayout.Tab tab) {
if(tab.getPosition() > 2) {
tabposition_number = tab.getPosition();
}
// viewPager.setCurrentItem(tab.getPosition());
if(tab.getPosition() == 1) {
toolbar.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.tab_contacts));
tabLayout.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.main_contacts));
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().setStatusBarColor(ContextCompat.getColor(MainActivity.this,R.color.status_contacts));
}
} else if(tab.getPosition() == 2) {
toolbar.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.tab_register));
tabLayout.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.main_register));
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().setStatusBarColor(ContextCompat.getColor(MainActivity.this,R.color.status_register));
}
} else {
toolbar.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.tab_signin));
tabLayout.setBackgroundColor(ContextCompat.getColor(MainActivity.this,R.color.main_signin));
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
getWindow().setStatusBarColor(ContextCompat.getColor(MainActivity.this,R.color.status_signin));
}
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
}
public void SetUpViewPager(ViewPager viewPager) {
MyViewPagerAdapter Adapter = new MyViewPagerAdapter((getSupportFragmentManager()));
Adapter.AddFragmentPage(new SignInFragment(),"ورود");
Adapter.AddFragmentPage(new ContactsFragment(),"ارتباطات");
Adapter.AddFragmentPage(new RegisterFragment(),"ثبت نام");
Adapter.notifyDataSetChanged();
viewPager.setAdapter(Adapter);
}
#Override
public void create_user_detail_tab(UserObject userObject) {
MyViewPagerAdapter Adapter = new MyViewPagerAdapter(getSupportFragmentManager());
UserDetailFragment userDetailFragment = new UserDetailFragment();
Bundle bundle = new Bundle();
bundle.putString("name",userObject.getName());
bundle.putString("family",userObject.getFamily());
bundle.putString("email",userObject.getEmail());
userDetailFragment.setArguments(bundle);
Adapter.AddFragmentPage(userDetailFragment,userObject.getName());
viewPager.setAdapter(Adapter);
TabLayout.Tab tab = tabLayout.getTabAt(1);
tab.select();
}
#Override
public void delete_previous_tab(int tabposition_number) {
remove_tab_details(tabposition_number);
MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter(getSupportFragmentManager());
myViewPagerAdapter.notifyDataSetChanged();
}
#Override
public void changeTabItem(boolean mustdelete) {
ContactsFragment contactsFragment = new ContactsFragment();
if(tabposition_number > 2 && mustdelete) {
contactsFragment.setTextView(tabposition_number,mustdelete);
TabLayout.Tab tab = tabLayout.getTabAt(1);
tab.select();
}
}
public class MyViewPagerAdapter extends FragmentPagerAdapter {
public MyViewPagerAdapter(FragmentManager manager) {
super(manager);
}
public void removeTabPage(int position) {
fragments.remove(position);
fragmentsTitle.remove(position);
MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter(getSupportFragmentManager());
myViewPagerAdapter.notifyDataSetChanged();
myViewPagerAdapter.notifyDataSetChanged();
}
public void AddFragmentPage(Fragment frag,String title) {
MainActivity.this.addToFragments(frag);
MainActivity.this.addToFragmentsTitle(title);
MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter(getSupportFragmentManager());
myViewPagerAdapter.notifyDataSetChanged();
}
public Fragment getItem(int position) {
return MainActivity.this.getFragmentsWithPosition(position);
}
public CharSequence getPageTitle(int position) {
return MainActivity.this.getFragmentsTitleWithPosition(position);
}
public int getCount() {
return fragments.size();
}
}
public void remove_tab_details(int tab_to_delete) {
// TabLayout.Tab tab = tabLayout.getTabAt(2);
// tab.select();
tabLayout.removeTabAt(tab_to_delete);
MyViewPagerAdapter Adapter = new MyViewPagerAdapter(getSupportFragmentManager());
Adapter.removeTabPage(tab_to_delete);
Adapter.notifyDataSetChanged();
}
}
and the code for UserDetailFragment ( which creates when the user click on one of the items in a listview fragment .
public class UserDetailFragment extends Fragment {
View view;
DetailCallBacks detailCallBacks;
public UserDetailFragment() {}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.user_detail_fragment,null);
return view;
}
#Override
public void onResume() {
super.onResume();
final Bundle bundle = getArguments();
String name = (String) bundle.get("name");
String family = (String)bundle.get("family");
String email = (String)bundle.get("email");
TextView nameFamilytv = view.findViewById(R.id.user_detail_name_and_family);
String nameAndfamily = name + " " + family;
nameFamilytv.setText(nameAndfamily);
TextView emailtv = view.findViewById(R.id.user_detail_email);
emailtv.setText(email);
Button closebtn = view.findViewById(R.id.detail_close_button);
closebtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
detailCallBacks.changeTabItem(true);
}
});
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
detailCallBacks = (DetailCallBacks)context;
}
public interface DetailCallBacks {
public void changeTabItem(boolean mustdelete);
}
and last but not least : the code for that list item that creates dynamic tabs when user clicks on its items :
public class ContactsFragment extends ListFragment {
CallBacks callBacks;
View view;
public static int came_fromTabItem;
public static boolean do_delete;
public ContactsFragment() { }
ArrayList<UserObject> userObjects;
BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
userObjects = intent.getParcelableArrayListExtra(Intent_Service.SERVICE_PAYLOAD);
ArrayAdapter<UserObject> userObjectArrayAdapter = new UserArrayAdapter(context,0,userObjects);
setListAdapter(userObjectArrayAdapter);
}
};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = new Intent(getActivity(), Intent_Service.class);
getActivity().startService(intent);
LocalBroadcastManager.getInstance(getActivity().getApplicationContext()).
registerReceiver(broadcastReceiver,new IntentFilter(Intent_Service.SERVICE_MESSAGE));
}
public void setTextView(int position,Boolean mustDelete) {
came_fromTabItem = position;
do_delete = mustDelete;
}
#Override
public void onResume() {
super.onResume();
if(came_fromTabItem > 2 && do_delete) {
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
callBacks.delete_previous_tab(came_fromTabItem);
do_delete = false;
Toast.makeText(getActivity().getApplicationContext(),String.valueOf(came_fromTabItem),Toast.LENGTH_LONG).show();
}
}, 2000);
}
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
this.view = inflater.inflate(R.layout.fragment_contacts,null);
return this.view;
}
public void onListItemClick(ListView l, View v, int position, long id) {
UserObject userObject = userObjects.get(position);
callBacks.create_user_detail_tab(userObject);
}
public interface CallBacks {
public void create_user_detail_tab(UserObject userObject);
public void delete_previous_tab(int positions);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
this.callBacks = (CallBacks)context;
}
}
So... can anyone help me please? the problem is simple, why the error The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 4, found: 3 appears when a tabitem is removed, how can I solve it?

the problem occur because you delete a tab item and your pager still has 4 in item count , you have to make pager item count dynamic , and call notifyDataSetChanged() after you remove an item
here is an example
public class MyPagerAdapter extends FragmentPagerAdapter {
int nbrItem;
public ProfilPagerAdapter(FragmentManager fm,String token,Int nbrItem) {
super(fm);
this.nbrItem= nbrItem;
}
#Override
public Fragment getItem(int position) {
switch(position) {
case 0 :
new SignInFragment();
case 1 :
new ContactsFragment()
case 2 :
new RegisterFragment()
}
return null;
}
#Override
public int getCount() {
return nbrItem;
}
public void setNbrItem(int nbrItem) {
this.nbrItem= nbrItem;
}
now when you remove an item you will pass to new number of item to your adapater
getAdapter().setNbrItem(2);
getAdapter().notifyDataSetChanged();

I solved my Problem, But with a hack, you see the error was because: TabItems are counting and indexing from 0, but as my pages are dynamically creating, I set the
getCount() method of my FragmentPagerAdapter to return the ArrayList<Fragment> fragments size , with fragments.size() , on the other hand, the size of an ArrayList doesn't count 0. so for 3 elements, instead of 0 1 2, or number 2, it returns to number 3.
so back to business, I was compelled to add null to my ArrayList and one null to my ArrayList titles, so this way when I removed my last TabItem, program doesn't crash anymore, and to be more convenient, when a user closes all Tabs , everytime user opens ( adds ) a new tab, I call fragments.removeAll(Collections.singleton(null)); to clear every null element i have inserted, for the TabTitles Too .
anyway cheers you guys, I'm sure this would be a good tutorial for those who want to create such applications because I've included all of my codes. please give a thumbs up. thanks.

Remove Tab Fragment from ViewPager and TabLayout Android

I have an activity that hosts tablayout with viewpager and fragments. I have successfully setup the tablayout and viewpager with user-populated values from a local database like below code(trying to be brief, showing only one tab here) -
public void setUpTabs() {
setUpViewPager(viewPager);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
tabLayout.setupWithViewPager(viewPager);
}
private void setUpViewPager(ViewPager viewPager) {
Customize customize = new Select()
.from(Customize.class)
.where("tabName = ? ", Constants.NATURE)
.executeSingle();
if (customize != null) {
String nature = customize.tabName;
Log.d(TAG, "Nature Tab Name:\t" + nature);
}
pagerAdapter = new TabsPagerAdapter(getSupportFragmentManager());
pagerAdapter.addTab(new Top30Fragment(), Constants.Top30); // default tab
if (nature != null) {
pagerAdapter.addTab(new NatureFragment(), Constants.NATURE); // dynamic tab from db
}
pagerAdapter.addTabAtLastPosition(new PrefsFragment(), Constants.PREFS);
viewPager.setAdapter(pagerAdapter);
}
Customize is model class, I have used ActiveAndroid library for persistence. Here's my tabsadapter class code:
public class TabsPagerAdapter extends FragmentPagerAdapter {
private static final String TAG = TabsPagerAdapter.class.getSimpleName();
private List<Fragment> fragmentList = new ArrayList<>();
private List<String> titlesList = new ArrayList<>();
private ViewPager viewPager;
private TabLayout tabLayout;
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
#Override
public int getCount() {
return fragmentList.size();
}
public void addTab(Fragment fragment, String name){
fragmentList.add(fragment);
titlesList.add(name);
}
public void addTabAtLastPosition(Fragment fragment, String name){
fragmentList.add(fragmentList.size(), fragment);
titlesList.add(name);
}
public void removeTab(Fragment fragment, String name){ //Not working
for (int i = 0; i < fragmentList.size(); i++){
if (fragmentList.get(i).equals(fragment)){ // never enters/returns from this loop
Log.d(TAG, "Fragment at position:\t" + i);
fragmentList.remove(fragment);
titlesList.remove(name);
}
}
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
return titlesList.get(position);
}
}
In my preferences fragment(also part of the tablayout), I have a recyclerview with checkboxes, case1:if checked, the tab is checked in db and only added to tablayout if not already there. case2:Otherwise if unchecked, means the tab is in layout and db and has to be removed from both.
I have started working on case 2 but I'm only able to delete values from db, the tab to be deleted is still present in tablayout. Here's my recyclerview adapter code to delete the tab:
public class PrefsAdapter extends RecyclerView.Adapter<PrefsCustomizeViewHolder> {
private static final String TAG = PrefsAdapter.class.getSimpleName();
private final Context context;
private List<Customize> itemsList;
private long id_nature, id_space, id_seasons, id_art, id_scifi, id_misc;
private Customize cust; // Model class for saving and retrieving tabs
private TabsPagerAdapter pagerAdapter;
private String nature, space, seasons, art, scifi, misc;
private String tabNature, tabSpace, tabSeasons, tabArt, tabScifi, tabMisc;
public PrefsAdapter(Context context, List<Customize> itemsList) {
this.context = context;
this.itemsList = itemsList;
pagerAdapter = new TabsPagerAdapter(((AppCompatActivity)context).getSupportFragmentManager());
}
#Override
public PrefsCustomizeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.prefs_customize_items_layout, parent, false);
return new PrefsCustomizeViewHolder(view);
}
#Override
public void onBindViewHolder(final PrefsCustomizeViewHolder viewholder, final int position) {
final Customize customize = itemsList.get(position);
Picasso.with(context)
.load(customize.getIcon())
.fit()
.into(viewholder.prefsSelImg);
// search db to find if checkbox is checked, i.e tab is present or not and update recyclerview
switch (position) {
case 0:
cust = new Select()
.from(Customize.class)
.where("tabName = ? ", Constants.SPACE)
.executeSingle();
if (cust != null) {
space = cust.tabName;
Log.d(TAG, "Space Tab From DB:\t" + space);
id_space = cust.getId();
Log.d(TAG, "Space Tab Id from DB:\t" + id_space);
viewholder.prefsCheckBox.setChecked(true);
} else {
viewholder.prefsCheckBox.setVisibility(View.INVISIBLE);
viewholder.prefsCheckBox.setChecked(false);
}
break;
}
viewholder.prefsSelImg.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
switch (position) {
case 0:
if (viewholder.prefsCheckBox.isChecked()){
viewholder.prefsCheckBox.setChecked(false);
Customize.delete(Customize.class, id_space);
Log.d(TAG, "Deleted Space id:\t" + id_space); // prints right log detail
pagerAdapter.removeTab(new SpaceFragment(), Constants.SPACE);
} else {
viewholder.prefsCheckBox.setChecked(true);
customize.setTabId(UUID.randomUUID().toString());
customize.setTabName(Constants.NATURE);
customize.save();
pagerAdapter.addTab(new SpaceFragment(), Constants.SPACE);
viewholder.prefsCheckBox.setVisibility(View.VISIBLE);
}
break;
}
}
});
}
#Override
public int getItemCount() {
if (itemsList == null) {
return 0;
}
return itemsList.size();
}
}
The tabspagerAdapter.removeTab() never gets called even though I have initialized it in the constructor like below:
public PrefsAdapter(Context context, List<Customize> itemsList) {
this.context = context;
this.itemsList = itemsList;
pagerAdapter = new TabsPagerAdapter(((AppCompatActivity)context).getSupportFragmentManager());
}
Can someone help me out with removing the fragment and also why the pagerAdapter.removeTab(fragment, title) method never gets called and how to update the tab layout. Thanks.

I have used the following code to successfully change the number of tabs (both add and remove). I found I had to remove them from both the pager adapter and the tab layout.
int cnp = mPagerAdapter.getCount();
// remove all tabs (or just the ones you need to remove)
// from both the pager adapter and the tab layout
for(int i = cnp-1; i >= 0; --i) {
mPagerAdapter.destroyItem(mViewPager, i, mPagerAdapter.getItem(i));
mTabLayout.removeTabAt(i);
}
// add back in whatever tabs you need and update the pager adapter to be consistent
mTabLayout.addTab(mTabLayout.newTab().setText("Tab 0"),0);
mTabLayout.addTab(mTabLayout.newTab().setText("Tab 1"),1);
mPagerAdapter.setConfiguration(2); // my custom method to tell it which pages to show
mTabLayout.invalidate();
mPagerAdapter.notifyDataSetChanged();
Relevant class members:
ViewPager mViewPager;
TabLayout mTabLayout;
MyPagerAdapter mPagerAdapter; // extends FragmentPagerAdapter

Dynamically add and remove tabs in TabLayout(material design) android

I have a TabLayout and inside that I have ViewPager. I need to dynamically add and remove tab in tablayout(material design). I can able to add the tabs dynamically but while removing the tab, tab is removing correctly. But viewpager last item is deleted. So tab is not showing specific fragment. FYI i have used FragmentPagerAdapter.
I have followed this tutorial to implement this
https://androidbelieve.com/navigation-drawer-with-swipe-tabs-using-design-support-library
public class TabFragment extends Fragment {
public static TabLayout tabLayout;
public static ViewPager viewPager;
public static int int_items = 2;
private MyNewsFragment mMyNewsFragment;
private ArrayList<TabFragmentModelClass> mFragmentArrayList;
private TabLayoutAdapter mTabLayoutAdapter;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
mMyNewsFragment = new MyNewsFragment();
/**
*Inflate tab_layout and setup Views.i;;a
*/
View x = inflater.inflate(R.layout.tab_layout, null);
tabLayout = (TabLayout) x.findViewById(R.id.tabs);
tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE); // scorllable tab
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL); // tab name fill parent
viewPager = (ViewPager) x.findViewById(R.id.viewpager);
mFragmentArrayList = new ArrayList<>();
mFragmentArrayList.add(new TabFragmentModelClass(new MyNewsSelectionFragment(), "", ""));
mFragmentArrayList.add(new TabFragmentModelClass(mMyNewsFragment, "", getResources().getString(R.string.mynews)));
mFragmentArrayList.add(new TabFragmentModelClass(new BreakingNewsFragment(), "", getResources().getString(R.string.breakingnews)));
// Selected news from shared preference
ArrayList<MyNewsSharedPreferenceModelClass> tempSharedPreferenceModelClass = new MyNewsSharedPreferenceClass().loadFavorites(getActivity());
for (int i = 0; i < tempSharedPreferenceModelClass.size(); i++) {
mFragmentArrayList.add(new TabFragmentModelClass(new CategoreyNewsFragment(tempSharedPreferenceModelClass.get(i).getmCatID()), tempSharedPreferenceModelClass.get(i).getmCatID(),
tempSharedPreferenceModelClass.get(i).getmCatName()));
}
}
/**
*Set an Apater for the View Pager
*/
mTabLayoutAdapter = new TabLayoutAdapter(getChildFragmentManager(), mFragmentArrayList);
viewPager.setAdapter(mTabLayoutAdapter);
viewPager.setOffscreenPageLimit(mFragmentArrayList.size());
tabLayout.setupWithViewPager(viewPager);
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
tabLayout.getTabAt(position);
}
#Override
public void onPageScrollStateChanged(int state) {
if (state == 1) {
updateMyNewsFragment();
}
}
});
/**
* Now , this is a workaround ,
* The setupWithViewPager dose't works without the runnable .
* Maybe a Support Library Bug .
*/
tabLayout.post(new Runnable() {
#Override
public void run() {
tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
switch (tab.getPosition()) {
case 1:
System.out.println("000000000000000000000 ");
updateMyNewsFragment();
break;
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
});
return x;
}
/**
* update the mynews selection
* this method trigger from the MainNewsActivity
*/
public void updateMyNewsFragment() {
if (ApplicationController.getInstance().getBoolPref(CommonVariableInterFace.isNewsSelected)) {
mMyNewsFragment.sendMyNewsRequest();
ApplicationController.getInstance().setBoolPref(CommonVariableInterFace.isNewsSelected, false);
}
}
/**
* update the tab values
* this method trigger from the MainNewsActivity
* if value is zero need to add in tab
* if value is one need to remove in tab
*/
public void updateTabvalue(String catId, String catName, int value) {
if (value == 0) { // add the value in tab
mFragmentArrayList.add(new TabFragmentModelClass(new CategoreyNewsFragment(catId), catId,
catName));
} else { // Removing the tab
for (int i = 0; i < mFragmentArrayList.size(); i++) {
if (mFragmentArrayList.get(i).getmCatID().equalsIgnoreCase(catId)) {
Log.i("-----same id ", catId);
mFragmentArrayList.remove(i);
mTabLayoutAdapter = new TabLayoutAdapter(getChildFragmentManager(), mFragmentArrayList);
viewPager.setAdapter(mTabLayoutAdapter);
}
}
}
mTabLayoutAdapter.notifyDataSetChanged();
viewPager.setOffscreenPageLimit(mFragmentArrayList.size());
tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);
tabLayout.setupWithViewPager(viewPager);
tabLayout.post(new Runnable() {
#Override
public void run() {
tabLayout.getTabAt(0).setIcon(R.mipmap.mynewselection);
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
switch (tab.getPosition()) {
case 1:
updateMyNewsFragment();
break;
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
});
}
public void openSpecificTab() {
// tabLayout.settab
// tabLayout.se
}
}
Adapter code:
public class TabLayoutAdapter extends FragmentPagerAdapter {
private long baseId = 0;
ArrayList<TabFragmentModelClass> fragmentAdapterArrayList;
public TabLayoutAdapter(FragmentManager fm, ArrayList<TabFragmentModelClass> fragmentArrayList) {
super(fm);
fragmentAdapterArrayList = fragmentArrayList;
}
#Override
public Fragment getItem(int position) {
if (position == 0)
return fragmentAdapterArrayList.get(position).getmFragment();
if (position == 1)
return fragmentAdapterArrayList.get(position).getmFragment();
if (position == 2)
return fragmentAdapterArrayList.get(position).getmFragment();
return new CategoreyNewsFragment().newInstance(fragmentAdapterArrayList.get(position).getmCatID());
}
#Override
public int getCount() {
return fragmentAdapterArrayList.size();
}
//this is called when notifyDataSetChanged() is called
#Override
public int getItemPosition(Object object) {
// refresh all fragments when data set changed
return TabLayoutAdapter.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;
}
/**
* // * This method returns the title of the tab according to the position.
* //
*/
#Override
public CharSequence getPageTitle(int position) {
return fragmentAdapterArrayList.get(position).getmCatName();
}
}

Remove tab from TabLayout
...
public void removeTab(int position) {
if (mTabLayout.getTabCount() >= 1 && position<mTabLayout.getTabCount()) {
mTabLayout.removeTabAt(position);
mPagerAdapter.removeTabPage(position);
}
}
...
Add a removeTabPage method to your PagerAdapter
...
public void removeTabPage(int position) {
if (!tabItems.isEmpty() && position<tabItems.size()) {
tabItems.remove(position);
notifyDataSetChanged();
}
}
...
Add a Tab
...
private void addTab(String title) {
mTabLayout.addTab(mTabLayout.newTab().setText(title));
mPagerAdapter.addTabPage(title);
}
...
Add a addTabPage method to your PagerAdapter
...
public void addTabPage(String title) {
tabItems.add(title);
notifyDataSetChanged();
}
...
Check out this sample code for a full example: ...samples/SupportDesignDemos/src/com/example/android/support/design/widget/TabLayoutUsage.java

With the new support library (I'm using 23.2.1) you should only add to the Viewpager and not the TabLayout (otherwise you end up with double tabs and other funky behavior). So to update TouchBoarder's answer:
Add a removeTabPage method to your PagerAdapter
public void removeTabPage(int position) {
if (!tabItems.isEmpty() && position<tabItems.size()) {
tabItems.remove(position);
notifyDataSetChanged();
}
}
Add a addTabPage method to your PagerAdapter
public void addTabPage(String title) {
tabItems.add(title);
notifyDataSetChanged();
}

In addition to existing answers, to remove all tabs from tabLayout.
tabLayout.removeAllTabs();

You can add dynamic tabs like this :
public void addTabs(){
for(YourClassModel tabName: tabsName){
Log.i("ActivityClass","tabName"+tabName);
tabLayout.addTab(tabLayout.newTab().setText(tabName.getName()));
}

Removetab from tablayout
TabActivity and ViewPager code :
`public class ScrollableTabsActivity extends AppCompatActivity {
int NumberOfTab = 5;
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
ViewPagerAdapter adapter ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scrollable_tabs);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
int length = tabLayout.getTabCount();
for (int i = 0; i < length; i++) {
tabLayout.getTabAt(i).setCustomView(getTabView(i));
}
}
public View getTabView(final int position) {
View view = LayoutInflater.from(this).inflate(R.layout.close_tablayout, null);
TextView title = (TextView) view.findViewById(R.id.title);
ImageView icon = (ImageView) view.findViewById(R.id.close);
title.setText(adapter.getPageTitle(position));
icon.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
NumberOfTab = NumberOfTab - 1;
setupViewPager(viewPager);
tabLayout.setupWithViewPager(viewPager);
if (tabLayout.getTabCount()==3)
tabLayout.setTabMode(TabLayout.MODE_FIXED);
int length = tabLayout.getTabCount();
for (int i = 0; i < length; i++) {
tabLayout.getTabAt(i).setCustomView(getTabView(i));
}
}
});
return view;
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
final Fragment result;
switch (position) {
case 0:
// First Fragment of First Tab
result = new OneFragment();
break;
case 1:
// First Fragment of Second Tab
result = new TwoFragment();
break;
case 2:
// First Fragment of Second Tab
result = new ThreeFragment();
break;
case 3:
// First Fragment of Second Tab
result = new FourFragment();
break;
case 4:
// First Fragment of Second Tab
result = new FiveFragment();
break;
default:
result = null;
break;
}
// Log.d("RESULT",result.getTag());
return result;
}
#Override
public int getCount() {
return NumberOfTab;
}
#Override
public CharSequence getPageTitle(final int position) {
switch (position) {
case 0:
return "One";
case 1:
return "Two";
case 2:
return "Three";
case 3:
return "Four";
case 4:
return "Five";
default:
return null;
}
}
}
}`
Check out this Links :
https://stackoverflow.com/a/58480151/9223264
I am new in stackoverflow i try my best if you think my answer is useful then please appreciate

Fragments not updating in viewpager

I am pretty new to ViewPager and adapter world in android. I have seen this issue asked many times but did not quite understand so hoping for a simplified answer :).
I have a ViewPager with 3 tabs and each tab has a fragment. By default the user first sees tab2 where he gives some imput to generate a string. this string then needs to be taken in tab3 which generates a qr code from it.
the string from tab 2 is updated to a class and tab3 takes the string from there.
My Problem is that when i move from tab2->tab3 the qr code is not generated. But when i go tab2->tab1->tab3 it is generated. I am guessing it retains my old fragment .
Below are my class codes. Could you please let me know why is this viewpager behaviour so.
my FragementActivity class:
public class ConfigExchangeMain extends FragmentActivity {
FragmentPagerAdapter adapterViewPager;
SampleFragementPagerAdapterExchange adapter;
String sent;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.config_exchange_main);
final ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
adapter=new SampleFragementPagerAdapterExchange(getSupportFragmentManager());
viewPager.setAdapter(adapter);
viewPager.setCurrentItem(1);
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setupWithViewPager(viewPager);
}
}
My Pager Adapter looks like
public class SampleFragementPagerAdapterExchange extends FragmentStatePagerAdapter {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[]{"CONTACTS", "HOME", "QR+SCAN"};
private ConfigDetail context;
public SampleFragementPagerAdapterExchange(FragmentManager fm) {
super(fm);
//this.context = context;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 1:
return new ConfigExchangeNFR();
case 0:
return new ConfigExchangeHome();
case 2:
return new ConfigExchangeQR();
default:
return new ConfigExchangeQR();
}
}
#Override
public int getCount() {
return PAGE_COUNT;
}
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
}
and my fragment in tab3 that is not updating:
public class ConfigExchangeQR extends Fragment {
ImageView iQRCode ;
int iQRDimension;
Button bScan;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
FacebookSdk.sdkInitialize(getActivity().getApplicationContext());
View view1 = inflater.inflate(R.layout.config_exchange_qr, container, false);
iQRCode = (ImageView)view1.findViewById(R.id.qrCode);
iQRDimension = 900;
String FinalQRCode = KeyValueDb.getPrefFinalVCard(getActivity());
QRCodeEncoder qrCodeEncoder = new QRCodeEncoder(FinalQRCode, null,
contents.Type.TEXT, BarcodeFormat.QR_CODE.toString(), iQRDimension);
try {
Bitmap bitmap = qrCodeEncoder.encodeAsBitmap();
iQRCode.setImageBitmap(bitmap);
} catch (WriterException e) {
e.printStackTrace();
}
bScan = (Button)view1.findViewById(R.id.scan_qr);
bScan.setOnClickListener(new View.OnClickListener() {
public void onClick(View paramAnonymousView) {
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
startActivityForResult(intent, 0);
}
});
return view1;
}
}

In ConfigExchangeMain class:
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
Fragment fragment= adapter.getItem(position);
if(fragment instanceof ConfigExchangeQR ){
((ConfigExchangeQR)fragment).update();
}
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
#Override
public void onDestroy() {
super.onDestroy();
viewPager.clearOnPageChangeListeners();
}
Add this method to your ConfigExchangeQR fragment
public class ConfigExchangeQR extends Fragment {
...
public void update(){
String FinalQRCode = KeyValueDb.getPrefFinalVCard(getActivity());
QRCodeEncoder qrCodeEncoder = new QRCodeEncoder(FinalQRCode, null,
contents.Type.TEXT, BarcodeFormat.QR_CODE.toString(), iQRDimension);
try {
Bitmap bitmap = qrCodeEncoder.encodeAsBitmap();
iQRCode.setImageBitmap(bitmap);
} catch (WriterException e) {
}
}
}

When you are currently in your second tab. The first and the third tab are preloaded (because the animation is smoother). When you switch to the first tab the third tab is unloaded -> so after switching back to the third tab it is recreated and it works for you.
The 3rd tab onCreateView is called before the 2nd tab is done, thats why it is not working. Try implementing logic inside the onResume() - to make sure it is always called when the focus is back on the fragment.
Hope this helps...
Cheers

How to save state of Fragments in ViewPager when orientation changes

I have an application that Implements ActionBarSherlock, it's mainly composed of
ViewPager with different content of fragments (for each page), with ViewPager indicator.
Here is my onCreate Method of the Activity that extends SherlockFragmentActivity
// Assume that tabs,sources,types are string arrays e.g. tabs = ["tab1","tab2","tab3"]
// types = ["listview","listview","webview"]
// according to the type of each tab, the type of content of the fragment associated to that tab is determined (e.g. WebView or ListView)
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.main);
srcContext = getBaseContext();
srcActivity = SaudiActivity.this;
int selectPos = 0;
Intent sender = getIntent();
FragmentPagerAdapter mAdapter = new NewsListAdapter(
getSupportFragmentManager());
ViewPager pager = (ViewPager) findViewById(R.id.pager);
pager.setAdapter(mAdapter);
TabPageIndicator indicator = (TabPageIndicator) findViewById(R.id.indicator);
indicator.setViewPager(pager);
pager.setOffscreenPageLimit(tabs.length);
pager.setCurrentItem((tabs.length - 1));
currentPosition = (tabs.length - 1);
indicator.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
currentPosition = position;
if ((type[position] == "listview" || type[position]
.equals("listview")) && loaded[position] == false) {
loaded[position] = true;
getNews(listViews[position], position);
}
}
#Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels) {
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
getSupportActionBar().setCustomView(R.layout.logo);
getSupportActionBar().setDisplayShowCustomEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
getSupportActionBar().setDisplayShowTitleEnabled(false);
getSupportActionBar().setDisplayShowHomeEnabled(false);
Context ctx = getSupportActionBar().getThemedContext();
SourcesAdapter adapter = new SourcesAdapter(ctx,
R.layout.navigation_list_item, src_name, icons, src_value);
}
Here are my News List Adapter (that creates the fragments),
public static class MyViewHolder {
public TextView title;
public ImageView icon;
}
class NewsListAdapter extends FragmentPagerAdapter {
public NewsListAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return new NewsFragment(MyActivity.this, position);
}
// This is the number of pages -- 5
#Override
public int getCount() {
return tabs.length;
}
// This is the title of the page that will apppear on the "tab"
public CharSequence getPageTitle(int position) {
return tabs[position];
}
}
public List<NewsItem> NewsItems;
Finally here's my NewsFragment:
public static class NewsFragment extends Fragment {
private int position;
public NewsFragment() {
}
public NewsFragment(Context ctx, int pos) {
this.position = pos;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = null;
if (type[position].equals("listview")) {
// Put a ListView in the Fragment
} else {
// Put a WebView in the Fragment
}
return view;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
}

Let the fragment handle it's state by overriding onSaveInstanceState and placing the necessary values into outState. Recover that state in onCreateView using savedInstanceState. Also I'm pretty sure that if you're using Actionbarsherlock fragments need to extend SherlockFragment rather than Fragment.