如何在android中计算生日剩余天数？

Question

我有一个DatePickerDialog用户选择了他的DOB（生日日期），现在我想计算生日的剩余天数？

    private void setDateTimeField () {
        final Calendar newCalendar = Calendar.getInstance();
        mDatePickerDialog = new DatePickerDialog(AddBirthday.this, new OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                Calendar newDate = Calendar.getInstance();
                newDate.set(year, monthOfYear, dayOfMonth);

                SuperActivityToast.create(AddBirthday.this, "Left days to birthday: ",
                        SuperToast.Duration.SHORT, Style.getStyle(Style.RED, SuperToast.Animations.FLYIN)).show();

//                Intent intent = new Intent(AddBirthday.this, AlarmReceiver.class);
//                PendingIntent pendingIntent = PendingIntent.getBroadcast(AddBirthday.this,
//                        0 , intent, PendingIntent.FLAG_UPDATE_CURRENT);
//                AlarmManager am = (AlarmManager) AddBirthday.this.getSystemService(AddBirthday.this.ALARM_SERVICE);
//                am.setRepeating(AlarmManager.RTC_WAKEUP, newDate.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
                mYear = c.get(Calendar.YEAR); mYear is type integer for storing current year
                getAge = mYear - year;
                if ( getAge == 0 || year >= 2016 ) {
                    SuperActivityToast.create(AddBirthday.this, "Invalid Date of Birthday!",
                            SuperToast.Duration.SHORT, Style.getStyle(Style.RED, SuperToast.Animations.FLYIN)).show();

                } else {
                    addBirthdayDate.setText(dateFormatter.format(newDate.getTime()));
                    dateSelected = String.valueOf(dayOfMonth) + " /" + String.valueOf(monthOfYear + 1)
                            + " /" + String.valueOf(year);
                }
            }
        }, newCalendar.get(Calendar.YEAR), newCalendar.get(Calendar.MONTH), newCalendar.get(Calendar.DAY_OF_MONTH));
    }

然后我想如果我可以给一个用户一些reccurence选择器来设置他想要通知直到生日的时间。