I have an app with string ressources for German and English. I defined a separate Fragment for chaging the laguage that you can see here

public class FR_Options extends Fragment implements View.OnClickListener {



    /*
    String specifying the language of the App
     */

    public static final String LANGUAGE_GERMAN = "German";
    public static final String LANGUAGE_ENGLISH = "English";
    //Set the default language to GERMAN
    public static String currentLanguageOfTheApp = LANGUAGE_ENGLISH;

    public FR_Options() {
        // Required empty public constructor
    }


    public static FR_Options newInstance(String param1, String param2) {
        FR_Options fragment = new FR_Options();

        return fragment;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }


    private FragmentOptionsBinding binding;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        binding = FragmentOptionsBinding.inflate(inflater, container, false);
        return binding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        binding.imageButtonGermany.setOnClickListener(this);
        binding.imageButtonUK.setOnClickListener(this);
        if(currentLanguageOfTheApp.equals(LANGUAGE_ENGLISH)) {
            binding.textViewCurrentLanguageValue.setText(LANGUAGE_ENGLISH);
            binding.imageButtonGermany.setAlpha(0.5f);
            binding.imageButtonUK.setAlpha(1.0f);
        }
        if(currentLanguageOfTheApp.equals(LANGUAGE_GERMAN)) {
            binding.textViewCurrentLanguageValue.setText(LANGUAGE_GERMAN);
            binding.imageButtonGermany.setAlpha(1.0f);
            binding.imageButtonUK.setAlpha(0.5f);
        }

    }


    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
    @Override
    public void onClick(View view) {

        if(view.getId() == R.id.imageButtonGermany) {

             /*
            Set the language to "German" for other fragments and database queries
             */

            this.currentLanguageOfTheApp = LANGUAGE_GERMAN;


            /*
            Set the language to "German" for the XML-layout files
             */



            Locale locale;
            locale = new Locale("de", "DE");

            Configuration config = new Configuration(getActivity().getBaseContext().getResources().getConfiguration());
            Locale.setDefault(locale);
            config.setLocale(locale);
            getActivity().recreate();

            getActivity().getBaseContext().getResources().updateConfiguration(config,
                    getActivity().getBaseContext().getResources().getDisplayMetrics());






        }

        if(view.getId() == R.id.imageButtonUK) {

            /*
            Set the language to "English" for other fragments and database queries
             */

            this.currentLanguageOfTheApp = LANGUAGE_ENGLISH;


            /*
            Set the language to "English" for the XML-layout files
             */


            Locale locale;
            locale = new Locale("en", "EN");

            Configuration config = new Configuration(getActivity().getBaseContext().getResources().getConfiguration());
            Locale.setDefault(locale);
            config.setLocale(locale);
            getActivity().recreate();

            getActivity().getBaseContext().getResources().updateConfiguration(config,
                    getActivity().getBaseContext().getResources().getDisplayMetrics());


        }


    }


}

Now when I navigate to a Test fragment whose Java file looks like this

public class Test extends Fragment  {



    int widthDisplay;
    int heightDisplay;


    private FragmentTestBinding binding;

    private ConstraintLayout constraintLayout;
    ConstraintSet constraintSet ;




    private boolean fragmentViewHasBeenCreated = false;


    int helpUpdateCounterProgressBar = 0;//Just for testing

    boolean animationIsWindBladRotating = false;



    private boolean sunIsShiningForImagewViews = false;

    private boolean helpSolarGameRectangleCorrectlyCaughtPreviously = false;

    public Test() {
        // Required empty public constructor
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        binding = FragmentTestBinding.inflate(inflater, container, false);

        WindowManager wm = (WindowManager) getActivity().getWindowManager();
        Display display = wm.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        widthDisplay = size.x;
        heightDisplay = size.y;

        //Test to set the string resources programmatically
        String goalText = getString(R.string.goal);
        String timeText = getString(R.string.time);
        binding.textViewGoal.setText(goalText);
        binding.textView3.setText(timeText);


        container.getContext();
        constraintLayout= binding.constraintLayout;


        fragmentViewHasBeenCreated = true;
        getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        constraintLayout = binding.constraintLayout;
        constraintSet = new ConstraintSet();
        return binding.getRoot();



    }//end onCreateView


    @Override
    public void onDestroyView() {
        super.onDestroyView();

        // Reset your variable to false
        fragmentViewHasBeenCreated = false;

    }
}

with the corrsponding xml layout file

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    tools:context=".MainActivity">


    <TextView
        android:id="@+id/textView_Goal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/goal"
        android:textSize="24dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/time"
        android:textSize="24dp"
        app:layout_constraintEnd_toEndOf="@+id/textView_Goal"
        app:layout_constraintStart_toStartOf="@+id/textView_Goal"
        app:layout_constraintTop_toBottomOf="@+id/textView_Goal" />


</androidx.constraintlayout.widget.ConstraintLayout>

The laguages of the string ressources android:text="@string/time" and android:text="@string/goal" never change and always remain English which is the default language.

In the folder values/string/strings.xml there are the two entries

"    <string name="goal">Goal</string>
    <string name="time">Time</string>"

while in the folder values/string/strings.mxl (de-rDE) there are the two entries “

Ziel
Zeit”

still the laguage is not changes in the Test class no matter what I do in the FR_Options fragment class.