Java Utililty Methods Calendar Day

long result = 0;
result = currentDate.get(Calendar.DAY_OF_YEAR);
return result;

cal.setTime(targetDate);
return cal.getActualMaximum(Calendar.DATE);

int huidigeDagVdMaand = cal.get(Calendar.DAY_OF_MONTH);
if (huidigeDagVdMaand >= startDayOfPeriod) {
    int diff = huidigeDagVdMaand - startDayOfPeriod;
    cal.add(Calendar.DAY_OF_MONTH, -(diff + 1));
} else {
    cal.add(Calendar.DAY_OF_MONTH, -huidigeDagVdMaand);
    while (cal.get(Calendar.DAY_OF_MONTH) >= startDayOfPeriod) {
        cal.add(Calendar.DAY_OF_MONTH, -1);
...

Calendar result = (Calendar) calendar.clone();
result.add(Calendar.DAY_OF_YEAR, -7);
result.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
result.set(Calendar.HOUR_OF_DAY, 24);
result.set(Calendar.MINUTE, 0);
result.set(Calendar.SECOND, 0);
result.set(Calendar.MILLISECOND, 0);
return result;
...

cal.add(Calendar.DATE, 1);
return cal.get(Calendar.DATE);

Calendar nextDay = (Calendar) calendar.clone();
nextDay.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + day);
return nextDay;

Calendar result = null;
result = date;
do {
    result = (Calendar) result.clone();
    result.add(Calendar.DATE, 1);
} while (result.get(Calendar.DAY_OF_WEEK) != 2);
return result;

if (day == null)
    day = new Date();
cal.setTime(day);
cal.set(Calendar.HOUR_OF_DAY, 12);
cal.set(Calendar.MINUTE, cal.getMinimum(Calendar.MINUTE));
cal.set(Calendar.SECOND, cal.getMinimum(Calendar.SECOND));
cal.set(Calendar.MILLISECOND, cal.getMinimum(Calendar.MILLISECOND));
return cal.getTime();
...

Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.add(Calendar.DATE, 1);
return cal;

Float totalInterest = 0.0f;
Float interestEarned = 0.0f;
for (int i = 1; i <= depositPeriod; i++) {
    Integer daysInMonth = currentDate.getActualMaximum(Calendar.DATE);
    for (int j = 0; j < daysInMonth; j++) {
        interestEarned = (float) (principal * interestPerDay);
        totalInterest += interestEarned;
        if (compoundingInterval == 0) {
...