How to scroll horizontaly a part of screen (Fragment or other ?)

Question

I am developping a simple "liste" application. A liste is made of Elements (name, price, date, and some other data) I have one, two, or more different listes, which are all based with Elements. In my main_activity I have some buttons to import, export data or add Element, modify color of the list, etc .. And also a spinner to choose another list, or create a new one. In the middle I have the content of one list (Elements) in a scrollable fragment

I would like to switch between my different lists on scrolling horizontally on the list view.

I have tried with androidx.viewpager and androidx.viewpager2, but this is very hard for me and not working. My need was very simple, and I am surprised not to find a simple solution

Here is some part of my code, scrolling between listes is not working

public class Element {
    public double montant;
    public String dateAchat;
    public String objet;
    public String magasin;
    public String dateRecue;

}

public class Liste {
    public String name;
    public int  colorText;
    public int  colorBack;

}

public class Variables {
    //static ArrayList<Element> elements = new ArrayList<>();
    static ArrayList<Liste> listes = new ArrayList<>();
    static int numListeEnCours = -1;
}



public class MainActivity extends AppCompatActivity {
    public MainActivity() {
        super(R.layout.activity_main);
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.i(TAG,"--------------debut oncreate");
        super.onCreate(savedInstanceState);
        appContext = this;
        myView = new View(this);
        Variables.listes = Fic.loadFileListes(appContext);
        int numPos = Variables.numListeEnCours;
        setContentView(R.layout.activity_main);
        viewPager = findViewById(R.id.viewpager);
        adapter = new FragmentPagerAdapter(new FragmentActivity());
        viewPager.setAdapter(adapter);
        initSpinner(numPos);
    }



public class FragmentPagerAdapter extends FragmentStateAdapter {
    private static String TAG = "dudu adapter";
    public FragmentPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }
    //@Override
    public Fragment getItem(int i) {
        Log.i(TAG,"GetItem appelé");
        Fragment fragment = new FragmentListe();
        return fragment;
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return null;
    }

    @Override
    public int getItemCount() {
        return Variables.listes.size()-1;
    }

}

I am working on fragments and pageadapter since 2 days, but I don't understand how it work, this seem very complicated for my simple need

adapter fragments FragmentStateAdapter