Java Utililty Methods Date Format Guess

for (String regexp : DATE_FORMAT_REGEXPS.keySet()) {
    if (dateString.toLowerCase().matches(regexp)) {
        return DATE_FORMAT_REGEXPS.get(regexp);
return null; 

for (String regexp : DATE_FORMAT_REGEXPS.keySet()) {
    if (dateString.toLowerCase().matches(regexp)) {
        return DATE_FORMAT_REGEXPS.get(regexp);
return null; 

for (String regexp : DATE_FORMAT_REGEXPS.keySet())
    if (dateString.toLowerCase().matches(regexp))
        return DATE_FORMAT_REGEXPS.get(regexp);
throw new ParseException("unable to parse date", 0);

SimpleDateFormat df = new SimpleDateFormat(simple);
try {
    return df.parse(df.format(date));
} catch (ParseException e) {
    e.printStackTrace();
return date;

String strDateTime = "";
DateFormat df = new SimpleDateFormat(format);
Calendar cal = Calendar.getInstance();
cal.setTime(date);
strDateTime = df.format(date);
return strDateTime;

if (date == null || date.equals("")) {
    return null;
SimpleDateFormat dateFormat = new SimpleDateFormat();
String[] patterns = new String[] { "yyyyMMdd'T'HHmmss'Z'", "yyyyMMdd'T'HHmmss", "yyyyMMdd", "yyyy-MM-dd" };
int[] patternsLength = new int[] { 16, 15, 8, 10 };
int s = patterns.length;
Date d = null;
...

if (date == null || date.equals("")) {
    return null;
SimpleDateFormat dateFormat = new SimpleDateFormat();
String[] patterns = new String[] { PATTERN_UTC, PATTERN_UTC_WOZ, PATTERN_UTC_WSEP, PATTERN_YYYY_MM_DD,
        PATTERN_YYYYMMDD, PATTERN_LOCALTIME, PATTERN_LOCALTIME_WOT, PATTERN_YYYY_MM_DD_HH_MM_SS };
int[] patternsLength = new int[] { PATTERN_UTC_LENGTH, PATTERN_UTC_WOZ_LENGTH, PATTERN_UTC_WSEP_LENGTH,
        PATTERN_YYYY_MM_DD_LENGTH, PATTERN_YYYYMMDD_LENGTH, PATTERN_LOCALTIME_LENGTH,
...

Matcher dateMatcher = dateRegex.matcher(date);
if (dateMatcher.matches()) {
    return new SimpleDateFormat(DATE_FORMAT);
Matcher timeMatcher = timeRegex.matcher(date);
if (timeMatcher.matches()) {
    return new SimpleDateFormat(TIME_FORMAT);
return new SimpleDateFormat(DATE_TIME_FORMAT);

int pos1 = dateStr.indexOf("-");
int pos2 = dateStr.indexOf(":");
DateFormat dt = null;
if (pos1 != -1 && pos2 != -1) {
    dt = fmtDT;
} else if (pos1 != -1 && pos2 == -1) {
    dt = fmtDate;
} else if (pos1 == -1 && pos2 != -1) {
...

return getDateFormatted(date, "dd/MM/yyyy");