TabLayout tabs text not displaying

The problem is you're calling setupWithViewPager() after setting up your tabs with the addTab() calls, effectively overwriting them.

From the documentation of TabLayout regarding setupWithViewPager():

The tabs displayed in this layout will be populated from the ViewPager adapter's page titles.

If you would like to use your TabLayout with a ViewPager, you should override getPageTitle() in your PagerAdapter (and remove the addTab() calls, they are redundant).

For example:

public class ExamplePagerAdapter extends FragmentStatePagerAdapter {

    // tab titles
    private String[] tabTitles = new String[]{"Tab1", "Tab2", "Tab3"};

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

    // overriding getPageTitle()
    @Override
    public CharSequence getPageTitle(int position) {
        return tabTitles[position];
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new Tab1Fragment();
            case 1:
                return new Tab2Fragment();
            case 2:
                return new Tab3Fragment();
            default:
                throw new RuntimeException("Invalid tab position");
        }
    }

    @Override
    public int getCount() {
        return tabTitles.length;
    }

    // ...
}

i added tab text and icon for each tab after calling tabs.setupWithViewPager(viewPager)

    viewPager.setAdapter(new MyViewAdapter(getSupportFragmentManager()));
    TabLayout tabs=(TabLayout) findViewById(R.id.tabs);
    tabs.setupWithViewPager(viewPager);
    tabs.getTabAt(0).setIcon(R.drawable.icon1);
    tabs.getTabAt(1).setIcon(R.drawable.icon2);
    tabs.getTabAt(0).setText(getResources().getText(R.string.tab1));
    tabs.getTabAt(1).setText(getResources().getText(R.string.tab2));

I'm using Kotlin and have spent an hour to find the bugs with this code.

var viewPager: ViewPager = view.findViewById(R.id.viewPager)

...

adapter = TabAdapter(fragmentManager!!)
adapter.addFragment(Fragment1(), "Fragment 1")
adapter.addFragment(Fragment2(), "Fragment 2")

viewPager.adapter = adapter

tabLayout.setupWithViewPager(viewpager)

I can compile this with no error, but the tab title is not showing until I realize the viewpager I assigned to the tabLayout is not viewPager (notice the capitalize 'P'). It's not producing error because kotlin will find any matching layout id, in this case "viewpager" which is a ViewPager but on another view.