Java Utililty Methods Month of Year

Calendar calendar = Calendar.getInstance();
curYear = calendar.get(Calendar.YEAR);
date = "" + curYear + "01";
return date;

Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month - 1);
cal.set(Calendar.DAY_OF_MONTH, day);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
return cal;
...

final Calendar now = Calendar.getInstance();
int month = now.get(Calendar.MONTH);
int year = now.get(Calendar.YEAR);
if (month == 0) {
    month = 12;
    year--;
} else {
    month--;
...

GregorianCalendar now = new GregorianCalendar();
now.add(2, -1);
return format(now.getTime(), "yyyyMM");

final Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DAY_OF_MONTH, -1);
final Date date = calendar.getTime();
final SimpleDateFormat formatter = new SimpleDateFormat("yyyyMM");
return formatter.format((date));

Calendar a = Calendar.getInstance();
a.setTime(new Date());
a.set(Calendar.DAY_OF_MONTH, -1);
return monthFormat.format(a.getTime());

int[] o = new int[2];
String day = (getThisMonthAndCycle()[0] + "").substring(4, 6);
int year = Integer.parseInt((getThisMonthAndCycle()[0] + "").substring(0, 4));
int month = getThisMonthAndCycle()[0];
int cycle = 0;
if (getThisMonthAndCycle()[1] == 1) {
    if ("01".equals(day)) {
        year--;
...

car.setTimeInMillis(System.currentTimeMillis());
return addMonth(-1);

DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();
c.add(Calendar.MONTH, -1);
return dateFormat.format(c.getTime());

Calendar calendar = Calendar.getInstance();
int year = Integer.parseInt(String.valueOf(date).substring(0, 4));
int month = Integer.parseInt(String.valueOf(date).substring(4, 6));
int day = Integer.parseInt(String.valueOf(date).substring(6, 8));
calendar.set(Calendar.YEAR, year);
calendar.set(Calendar.MONTH, month - 1);
calendar.set(Calendar.DAY_OF_MONTH, day);
calendar.add(Calendar.MONTH, -1);
...