Dynamically add and remove tabs in TabLayout(mater

Question

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();
    }
}

Answer 1

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

Answer 2

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();
}