Java Utililty Methods Month Day

Calendar cal = Calendar.getInstance();
cal.set(Calendar.DAY_OF_MONTH, 1);
return new SimpleDateFormat("yyyy-MM-dd ").format(cal.getTime());

SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
cal.add(Calendar.MONTH, -1);
cal.set(Calendar.DAY_OF_MONTH, 1);
return format.format(cal.getTime());

Date date = new Date();
SimpleDateFormat format = new SimpleDateFormat(YYYYMMDD);
Calendar sCal = Calendar.getInstance();
sCal.setTime(date);
sCal.add(Calendar.DAY_OF_MONTH, -(sCal.get(Calendar.DAY_OF_MONTH) - 1));
try {
    date = format.parse(format.format(sCal.getTime()));
} catch (ParseException e) {
...

int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = 1;
c.set(year, month, day, 0, 0, 0);
return c.getTime();

Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.set(Calendar.DAY_OF_MONTH, cal.getMinimum(Calendar.DATE));
return date2String(cal.getTime());

if (null == date)
    return null;
return parserDate(getFirstDayStringOfMonth(date), format2);

Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), 1);
return calendar.getTime();

Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), 1);
return calendar.getTime();

Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(Calendar.DAY_OF_MONTH, 1);
return startOfDay(calendar.getTime());

Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(date);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.clear(Calendar.MINUTE);
cal.clear(Calendar.SECOND);
cal.clear(Calendar.MILLISECOND);
cal.set(Calendar.DAY_OF_MONTH, Calendar.getInstance().getActualMinimum(Calendar.DAY_OF_MONTH));
return cal.getTimeInMillis();
...