Java Utililty Methods ZoneId

ZoneId determineTimeZoneId(String zoneId)
determine Time Zone Id

try {
 return ZoneId.of(zoneId);
} catch (Exception e) {
 return ZoneId.systemDefault();

LocalDateTime fromEpochMilliseconds(final Long fromEpoch)
from Epoch Milliseconds

return LocalDateTime.ofInstant(Instant.ofEpochMilli(fromEpoch), systemDefaultZoneId);

ZoneId getDefaultTimeZone()
get Default Time Zone

return ZoneId.systemDefault();

ZoneId getDefaultZoneId()
Returns the default zone id used dor user interface (UI)

return defaultZoneId;

ZoneId getDefaultZoneId()
get Default Zone Id

ZoneId zone = null;
try {
 try {
 String id = System.getProperty("user.timezone");
 if (id != null) {
 zone = ZoneId.of(id);
 } catch (RuntimeException ex) {
...

ZoneId getRequestTimeZone(String timestamp)
Return the ZoneId of given ISO8601 timestamp

return ZonedDateTime.parse(timestamp).getZone();

ZoneId getTimezone(String tzid)
Get the ZoneId of a String that could be a valid tzid.

try {
 return ZoneId.of(tzid);
} catch (Exception e) {
 return ZoneId.of("America/New_York");

ZoneId getTimeZoneId(final TimeZone tz)
Get time zone id .ZoneId.SHORT_IDS used get id if time zone is abbreviated like 'IST'.

return ZoneId.of(tz.getID(), ZoneId.SHORT_IDS);

ZonedDateTime getZoneDateTime(Date d, String tzId)
get Zone Date Time

long milli = (d == null ? new Date() : d).getTime();
return Instant.ofEpochMilli(milli).atZone(getZoneId(tzId));

ZoneId getZoneId()
get Zone Id

return ZoneId.systemDefault();