onTabSelected Selected Not Called

When you call setupWithViewPager, this will internally call setOnTabSelectedListener(new ViewPagerOnTabSelectedListener(viewPager));, overriding your OnTabSelectedListener.

Instead, your listener should extend TabLayout.ViewPagerOnTabSelectedListener, then override onTabSelected() and call setOnTabSelectedListener() after setupWithViewPager():

tabLayout.setupWithViewPager(mViewPager);
tabLayout.setOnTabSelectedListener(
  new TabLayout.ViewPagerOnTabSelectedListener(mViewPager) {
    @Override
    public void onTabSelected(TabLayout.Tab tab) {
        super.onTabSelected(tab);
        numTab = tab.getPosition();
        prefs.edit().putInt("numTab", numTab).apply();
    }
});