Java Utililty Methods Day End

List<Date> list = new ArrayList<Date>();
GregorianCalendar gc1 = new GregorianCalendar(), gc2 = new GregorianCalendar();
gc1.setTime(startDate);
gc2.setTime(endDate);
do {
    GregorianCalendar gc3 = (GregorianCalendar) gc1.clone();
    list.add(gc3.getTime());
    System.out.println(gc3.getTime());
...

Calendar c = Calendar.getInstance();
c.clear();
Calendar co = Calendar.getInstance();
co.setTime(d);
c.set(Calendar.DAY_OF_MONTH, co.get(Calendar.DAY_OF_MONTH));
c.set(Calendar.MONTH, co.get(Calendar.MONTH));
c.set(Calendar.YEAR, co.get(Calendar.YEAR));
c.add(Calendar.DAY_OF_MONTH, 1);
...

return getDateEndDay(getDateNow());

Calendar c = Calendar.getInstance();
c.setTime(date);
int second = c.get(Calendar.SECOND);
int hour = c.get(Calendar.HOUR);
c.set(Calendar.SECOND, second + 3);
c.set(Calendar.HOUR, hour - hourModify);
return c.getTime();

int differ = getDifferDays(begin, end);
List<Date> temp = new ArrayList<Date>(differ);
for (int i = 0; i <= differ; i++) {
    CALENDAR.setTime(begin);
    CALENDAR.add(Calendar.DATE, i);
    temp.add(CALENDAR.getTime());
return temp;
...

List<Date> dateList = new ArrayList<Date>();
dateList.add(beginDate);
Calendar cal = Calendar.getInstance();
cal.setTime(beginDate);
boolean bContinue = true;
while (bContinue) {
    cal.add(Calendar.SECOND, 1);
    if (endDate.after(cal.getTime())) {
...

StringBuilder b = new StringBuilder();
Calendar cal = Calendar.getInstance();
b.append(getFixedString(cal.get(Calendar.YEAR), 4));
b.append(getFixedString(cal.get(Calendar.MONTH) + 1, 2));
b.append(getFixedString(cal.get(Calendar.DAY_OF_MONTH), 2));
b.append("_");
b.append(getFixedString(cal.get(Calendar.HOUR_OF_DAY), 2));
b.append(getFixedString(cal.get(Calendar.MINUTE), 2));
...

Calendar endDate = Calendar.getInstance();
endDate.set(Calendar.HOUR_OF_DAY, LAST_HOUR);
endDate.set(Calendar.MINUTE, LAST_MINUTE);
endDate.set(Calendar.SECOND, LAST_SECOND);
endDate.set(Calendar.MILLISECOND, LAST_MILLISECOND);
return endDate;

long totalDate = 0;
Calendar calendar = Calendar.getInstance();
calendar.setTime(startDate);
long timestart = calendar.getTimeInMillis();
calendar.setTime(endDate);
long timeend = calendar.getTimeInMillis();
totalDate = Math.abs((timeend - timestart)) / (1000 * 60 * 60 * 24);
return totalDate;
...

Calendar calendarEndDate = Calendar.getInstance();
calendarEndDate.add(Calendar.YEAR, 1);
return calendarEndDate;