Java Utililty Methods Date Format ISO

DateFormat dateFormat = new SimpleDateFormat(mask);
dateFormat.setLenient(false);
dateFormat.setTimeZone(tz);
return dateFormat;

DateFormat dfm = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.ENGLISH);
dfm.setTimeZone(TimeZone.getTimeZone("GMT"));
return dfm.format(d);

Calendar calendar = Calendar.getInstance(timeZone);
calendar.setTimeInMillis(timestampWithMilliseconds);
calendar.set(Calendar.HOUR, 0);
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
calendar.setTimeZone(timeZone);
return getIso8601DateFormat().format(calendar.getTime());
...

return new SimpleDateFormat(formatIso8601Day);

lock.lock();
try {
    try {
        return getDateFormat().parse(in);
    } catch (ParseException e) {
        throw new RuntimeException("Date failed to parse as ISO 8601: " + in);
} finally {
...

SimpleDateFormat sdf = new SimpleDateFormat(ISO_8601_FORMAT);
String result = "";
if (d != null) {
    result = sdf.format(d);
return result;

String result = ISO8601.format(date);
result = result.substring(0, result.length() - 2) + ":" + result.substring(result.length() - 2);
return (result);

GregorianCalendar calendar = new GregorianCalendar();
calendar.setTime(date);
int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH) + 1;
int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
int hour = calendar.get(Calendar.HOUR_OF_DAY);
int minute = calendar.get(Calendar.MINUTE);
int second = calendar.get(Calendar.SECOND);
...

DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
return df.format(new Date());

Date nowDate = date;
if (null == date) {
    nowDate = new Date();
SimpleDateFormat df = new SimpleDateFormat(FORMAT_ISO8601);
df.setTimeZone(new SimpleTimeZone(0, TIME_ZONE));
return df.format(nowDate);