'java.lang.String android.content.Context.getPackageName()' on a null object refrence

Question

find many solutions but not solve my problem where I am going to wrong please anyone correct me. I am a beginner to set an Alarm in the application.

public void setAlarm(String alarmTime) {
            //Toast.makeText(getActivity(), "set Alarm", Toast.LENGTH_LONG).show();
            Date date = null;
            try {`enter code here`
                SimpleDateFormat formatter = new SimpleDateFormat("hh:mm:ss a");
                date = (Date) formatter.parse(alarmTime);
            } catch (Exception e) {
                e.printStackTrace();
            }
    
            Intent intent = new Intent(getActivity(), AlarmAlert.class);//problem here getActivity()
            AlarmManager alarmManager = (AlarmManager) getActivity().getSystemService(Context.ALARM_SERVICE);
            PendingIntent pendingIntent = PendingIntent.getBroadcast(getContext(), 0, intent, 0);
            assert date != null;
            alarmManager.setExact(AlarmManager.RTC_WAKEUP, date.getTime(), pendingIntent);
            Toast.makeText(getActivity(), "Set Alarm", Toast.LENGTH_SHORT).show();
    
        }