Java Utililty Methods Timestamp Format

if (timestamp <= 0) {
    return "null";
} else {
    return timestampDateFormat.get().format(new Date(timestamp));

Date date = new Date(timestamp);
final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); 
df.setTimeZone(tzUTC);
return timestamp + " (" + df.format(date) + ")";

return new SimpleDateFormat("HH:mm:ss.SSS", Locale.ROOT).format(new Date(ts));

SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy");
SimpleDateFormat yearMonthDayFormat = new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat iso8601Format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
String timestamp = null;
try {
    if (dateStr == null) {
    } else if (dateStr.length() == 4) {
        Date yearDate = yearFormat.parse(dateStr);
...

if (dataHora == null)
    return "";
SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
return format.format(dataHora);

SimpleDateFormat formatter = (SimpleDateFormat) DateFormat.getDateTimeInstance(DateFormat.MONTH_FIELD,
        DateFormat.LONG, Locale.US);
formatter.setTimeZone(TimeZone.getTimeZone("GMT"));
formatter.applyPattern("yyyy-MM-dd");
String timestamp = formatter.format(t);
formatter.applyPattern("hh:mm:ss");
return timestamp + "T" + formatter.format(t) + "Z";

DateFormat format = null;
switch (type) {
case FORMAT_DD_MM_YYYY_HH_MM_SS:
    format = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
    break;
case FORMAT_YYYY_MM_DD_HH_MM_SS:
    format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    break;
...

if (timestamp != null) {
    DateFormat formatter = new SimpleDateFormat(DATE_TIME_PATTERN);
    return formatter.format(timestamp.getTime());
return null;

String timeStr = "";
if (timestamp != null) {
    timeStr = getStrDate(new Long(timestamp.getTime()), iType);
return timeStr;

return new SimpleDateFormat(pattern).format(timestamp);