Refresh Fragment at reload

Question

I think you want to refresh the fragment contents upon db update

If so, detach the fragment and reattach it

// Reload current fragment
Fragment frg = null;
frg = getSupportFragmentManager().findFragmentByTag("Your_Fragment_TAG");
final FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.detach(frg);
ft.attach(frg);
ft.commit();

Your_Fragment_TAG is the name you gave your fragment when you created it

This code is for support library.

If you're not supporting older devices, just use getFragmentManager instead of getSupportFragmentManager

[EDIT]

This method requires the Fragment to have a tag.
In case you don't have it, then @Hammer's method is what you need.

This will refresh current fragment :

FragmentTransaction ft = getFragmentManager().beginTransaction();
if (Build.VERSION.SDK_INT >= 26) {
   ft.setReorderingAllowed(false);
}
ft.detach(this).attach(this).commit();

In case you do not have the fragment tag, the following code works well for me.

 Fragment currentFragment = getActivity().getFragmentManager().findFragmentById(R.id.fragment_container);
    
   if (currentFragment instanceof "NAME OF YOUR FRAGMENT CLASS") {
       FragmentTransaction fragTransaction =   (getActivity()).getFragmentManager().beginTransaction();
       fragTransaction.detach(currentFragment);
       fragTransaction.attach(currentFragment);
       fragTransaction.commit();
    }

To refresh the fragment accepted answer will not work on Nougat and above version. To make it work on all os you can do following.

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        fragmentManager.beginTransaction().detach(this).commitNow();
        fragmentManager.beginTransaction().attach(this).commitNow();
    } else {
        fragmentManager.beginTransaction().detach(this).attach(this).commit();
    }

you can refresh your fragment when it is visible to user, just add this code into your Fragment this will refresh your fragment when it is visible.

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        // Refresh your fragment here          
  getFragmentManager().beginTransaction().detach(this).attach(this).commit();
        Log.i("IsRefresh", "Yes");
    }
}

You cannot reload the fragment while it is attached to an Activity, where you get "Fragment Already Added" exception.

So the fragment has to be first detached from its activity and then attached. All can be done using the fluent api in one line:

getFragmentManager().beginTransaction().detach(this).attach(this).commit();

Update: This is to incorporate the changes made to API 26 and above:

FragmentTransaction transaction = mActivity.getFragmentManager()
                        .beginTransaction();
                if (Build.VERSION.SDK_INT >= 26) {
                    transaction.setReorderingAllowed(false);
                }
                transaction.detach(this).attach
                        (this).commit();

For more description of the update please see https://stackoverflow.com/a/51327440/4514796