Java Utililty Methods Day Between

int weeks = 0;
Calendar aCal = Calendar.getInstance();
Calendar bCal = Calendar.getInstance();
aCal.setTime(a);
bCal.setTime(b);
Calendar startCal, endCal;
if (aCal.before(bCal)) {
    startCal = aCal;
...

long startMil = 0;
long endMil = 0;
Calendar calendar = Calendar.getInstance();
calendar.setTime(time1);
calendar.set(1900, 1, 1);
startMil = calendar.getTimeInMillis();
calendar.setTime(time2);
calendar.set(1900, 1, 1);
...

return (int) getMillisecondDifference(begin, end) / 60000;

Calendar fromCalendar = toMidnightCalendar(from);
Calendar toCalendar = toMidnightCalendar(to);
return getMonthDifference(fromCalendar, toCalendar);

Date span = new Date(laterDate.getTime() - earlierDate.getTime());
Date firstDate = new Date(0);
Calendar calendar = Calendar.getInstance();
calendar.setTime(firstDate);
int firstYear = calendar.get(Calendar.YEAR);
int firstMonth = calendar.get(Calendar.MONTH);
calendar.setTime(span);
int spanYear = calendar.get(Calendar.YEAR);
...

int result = 0;
Calendar cal = new GregorianCalendar();
cal.setTime(date1);
while (!cal.getTime().after(date2)) {
    cal.add(Calendar.DAY_OF_MONTH, 1);
    result++;
return result;
...

long[] result = new long[5];
Calendar cal = Calendar.getInstance();
cal.setTime(d1);
long t1 = cal.getTimeInMillis();
cal.setTime(d2);
long diff = Math.abs(cal.getTimeInMillis() - t1);
final int ONE_DAY = 1000 * 60 * 60 * 24;
final int ONE_HOUR = ONE_DAY / 24;
...

Calendar dateCalendar1 = Calendar.getInstance();
dateCalendar1.setTime(date1);
Calendar dateCalendar2 = Calendar.getInstance();
dateCalendar2.setTime(date2);
return (dateCalendar1.getTimeInMillis() - dateCalendar2.getTimeInMillis()) / 1000;

if (otherDate == null) {
    throw new IllegalArgumentException("Invalid Date Parameter!");
Calendar now = Calendar.getInstance();
now.setTime(new Date());
Calendar aPointInTime = Calendar.getInstance();
aPointInTime.setTime(otherDate);
return aPointInTime.getTimeInMillis() - now.getTimeInMillis();
...

int diffCnt = 0;
int yyyy = 0;
int mm = 0;
int dd = 0;
Date today = new Date();
yyyy = Integer.parseInt(diffDate.substring(0, 4));
mm = Integer.parseInt(diffDate.substring(4, 6));
dd = Integer.parseInt(diffDate.substring(6, 8));
...