Java settitle does not work properly

I created a sliding tab activity and tried to change the title of the application bar dynamically. But everything I did didn't seem to work! This is my mainactivity.java:

public class MainActivity extends AppCompatActivity {


ViewPager mPager;
SlidingTabLayout mTabs;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    getSupportActionBar().setDisplayShowHomeEnabled(true);


    mPager = (ViewPager) findViewById(R.id.pager);

    mPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

    mTabs = (SlidingTabLayout) findViewById(R.id.tabs);

    mTabs.setCustomTabView(R.layout.custom_tab_view, R.id.tabText);

    mTabs.setDistributeEvenly(true);

    mTabs.setSelectedIndicatorColors(getResources().getColor(R.color.colorAccent));
    mTabs.setBackgroundColor(getResources().getColor(R.color.colorPrimary));

    mTabs.setViewPager(mPager);

}

class MyPagerAdapter extends FragmentPagerAdapter {

    int tabIcons[] = {R.drawable.ic_events, R.drawable.ic_clients, R.drawable.ic_history};
    String[] tabText = getResources().getStringArray(R.array.tabs);

    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {

        switch (position){
            case 0:
                getSupportActionBar().setTitle("Events");
                EventsFragment eventsFragment = EventsFragment.getInstance(position);
                return eventsFragment;

            case 1:
                getSupportActionBar().setTitle("Clients");
                ClientsFragment clientsFragment = ClientsFragment.getInstance(position);
                return clientsFragment;

            case 2:
                getSupportActionBar().setTitle("History");
                HistoryFragment historyFragment = HistoryFragment.getInstance(position);
                return historyFragment;

            default:
                getSupportActionBar().setTitle("Events");
                EventsFragment defaultFragment = EventsFragment.getInstance(position);
                return defaultFragment;

        }

    }

    @Override
    public CharSequence getPageTitle(int position) {

        Drawable drawable = getResources().getDrawable(tabIcons[position]);

        drawable.setBounds(0,0,64,64);

        ImageSpan imageSpan = new ImageSpan(drawable);

        SpannableString spannableString = new SpannableString(" ");

        spannableString.setSpan(imageSpan, 0, spannableString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

        return spannableString;
    }

    @Override
    public int getCount() {
        return 3;
    }
}

}

I also tried to set the title of the application bar in the oncreate method using the following method:

 getSupportActionBar().setTitle("Test");

It doesn't work either

How can I solve it? thank you!

resolvent:

Call the settitle method on the mainactivity object

Calling from inside mainactivity: settitle (...) only. Calling from another class (mypageradapter): activity. Settitle (...)

An activity is a reference to the mainactivity object. You can use getactivity(), which returns the activity associated with the fragment

Finally, use getactivity(). Settitle (...); To set the title from the clip