AlertDialog NumberPicker that opens after a TimePicker is set

Question

I'm trying to implement a functionality such that after the user sets a time (from a TimePicker) I need the user to supply a number (between 1 and 24) that will be stored in a variable. The TimePicker is already implemented:

public class MedicationActivity extends AppCompatActivity {
   
    Button setA;
   
    TextView textA;
    
    TimePickerDialog pickerA;
    

    String filename = "pills";
    Calendar calendar = Calendar.getInstance();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_medication);
        textA = (TextView) findViewById(R.id.alarmprompt);
        setA = (Button) findViewById(R.id.setA);
        

setA.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View a) {
                textA.setText("");


                pickerA = new TimePickerDialog(MedicationActivity.this,
                            onTimeSetListenerA,
                            calendar.get(Calendar.HOUR_OF_DAY),
                            calendar.get(Calendar.MINUTE),
                            true);
                pickerA.setTitle("Set Pill Time");
                pickerA.show();

            }
        });  
TimePickerDialog.OnTimeSetListener onTimeSetListenerA = new TimePickerDialog.OnTimeSetListener() {

        @Override
        public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

            Calendar calNow = Calendar.getInstance();
            Calendar calSet = (Calendar) calNow.clone();

            calSet.set(Calendar.HOUR_OF_DAY, hourOfDay);
            calSet.set(Calendar.MINUTE, minute);
            calSet.set(Calendar.SECOND, 0);
            calSet.set(Calendar.MILLISECOND, 0);

            if (calSet.compareTo(calNow) <= 0) {
                // Today Set time passed, count to tomorrow
                calSet.add(Calendar.DATE, 1);
            }


            Context context = getApplicationContext();


            File file = new File(context.getExternalFilesDir(null).getAbsolutePath(), filename + "A.txt");

            Log.d("Logging to", String.valueOf(file));
            int month = calSet.get(Calendar.MONTH)+1;
            int day = calSet.get(Calendar.DAY_OF_MONTH);

            String data = calSet.get(Calendar.HOUR_OF_DAY) + ","
                            +calSet.get(Calendar.MINUTE) + ","
                            +day+ "," + month + ","
                            +calSet.get(Calendar.YEAR) + ",";

            textA.setText(+ calSet.get(Calendar.HOUR_OF_DAY) + ":"+ calSet.get(Calendar.MINUTE) +" \n\n\n "+ day +"." + month+"."+calSet.get(Calendar.YEAR));


            try {
                FileOutputStream stream = new FileOutputStream(file, false);
                try {
                    stream.write(data.getBytes());

                }catch (Exception e){
                    e.printStackTrace();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }



        }
    };

From my understanding, I have to implement an AlertDialog to pop-up, that contains a NumberPicker. The problem is that I have tried several methods and failed to implement the alert dialog. Aspects worth mentioning: This is not the MainActivity it is a child activity. When I tried to implement a NumberPickerDialogFragment and add the

public class MedicationActivity extends AppCompatActivity implements NumberPickerDialogFragment 

there was a conflict between onStart() of the AppCompatActivity and onStart() of the NumberPickerDialogFragment.

Can I get a helping hand, please?

UPDATE 1:

added the following code:

 public void showNumberPicker(View view){
        NumberPickerDialog newFragment = new NumberPickerDialog();
        newFragment.setValueChangeListener(newFragment.getValueChangeListener());
        newFragment.show(getSupportFragmentManager(), "time picker");
    }

 TimePickerDialog.OnTimeSetListener onTimeSetListenerA = new TimePickerDialog.OnTimeSetListener() {

        @Override
        public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

            setContentView(R.layout.number_picker_dialog);
            showNumberPicker(view);

The NumberPicker opens in a DialogFragment but after number picking and press ok, the app Crashes

Update 2:

The main suspect is this line:

newFragment.setValueChangeListener(newFragment.getValueChangeListener());

I suspect that newFragment.getValueChangeListener() because I get this when the app crashes:

The other posts I have seen use a this instead of newFragment.getValueChangeListener()

Thank you.