How to replace a fragment in a FragmentStateAdapter

Question

I have a "main" fragment that contains tabs on the side, and when I click on any of those tabs, the ViewPager2 of the "main" fragment jumps to the specific fragment (each fragment is of a different class) in the FragmentStateAdapter.

Let's say that for one of those fragments, it has a button where if pressed, it replaces the current fragment in the FragmentStateAdapter, but the tabs are still at the side (we are still in the "main" fragment"). If I click on any of the tabs, I want it to work as before where it goes to the specific fragment.

I want to do this but I'm not sure how to do it or if it is the correct approach. Should I replace one of the fragments in the FragmentStateAdapter, or should I just destroy the ViewPager2 altogether and replace it with that desired fragment? Or is there a better approach?

This is how that FragmentStateAdapter looks like and I want to replace the EscortFragment when a button in it is clicked, with a different fragment.

public class HomeTabAdapter extends FragmentStateAdapter {
    private ArrayList<Fragment> fragments;
    private Context context;

    public HomeTabAdapter(@NonNull FragmentManager fragmentManager, @NonNull Lifecycle lifecycle, Context context) {
        super(fragmentManager, lifecycle);
        this.context = context;
        fragments = new ArrayList<>();
        fragments.add(new HomeFragment());
        fragments.add(new PurposeOfVisitFragment());
        fragments.add(new GalleryFragment());
        fragments.add(new EscortFragment());
        fragments.add(new MapsFragment());
        fragments.add(new FaqFragment());
        fragments.add(new SupportFragment());
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fragments.get(position);
    }

    @Override
    public int getItemCount() {
        return fragments.size();
    }
}

Answer 1

Briefly, in your HomeTabAdapter class override getItemId() to generate a unique ID value for each of your fragments. Next time the base class FragmentStateAdapter needs to access the fragment, it will see a different ID value for that position. This will cause it to call createFragment() again for that position.

And if you override getItemId(), you must also override containsItem().

So, for example, add the following to your HomeTabAdapter class:

@Override
public long getItemId(int position) {
    Fragment fragment = fragments.get(position);
    long id = getIDForFragment(fragment);
    return id;
}

@Override
public boolean containsItem(long itemId) {
    for (Fragment fragment : fragments) {
        if (getIDForFragment(fragment) == itemId)
            return true;
    }
    return false;
}

private long getIDForFragment(Fragment fragment)
{
    // Insert code that generates a unique ID value for each Fragment here.
}

public void replaceFragment(int index, Fragment fragment) {
    fragments.set(index, fragment);
    notifyDataSetChanged();
}

Notice that the method replaceFragment() calls notifyDataSetChanged(). This forces to check ID values immediately, rather than waiting until some later time.