When I create a new Date object, it is initialized to the current time but in the local timezone. How can I get the current date and time in GMT?
This question is related to
java
date
localization
timezone
gmt
The answer is
This worked for me, returns the timestamp in GMT!
Date currDate;
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
SimpleDateFormat dateFormatLocal = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
long currTime = 0;
try {
currDate = dateFormatLocal.parse( dateFormatGmt.format(new Date()) );
currTime = currDate.getTime();
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Use this Class to get ever the right UTC Time from a Online NTP Server:
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
class NTP_UTC_Time
{
private static final String TAG = "SntpClient";
private static final int RECEIVE_TIME_OFFSET = 32;
private static final int TRANSMIT_TIME_OFFSET = 40;
private static final int NTP_PACKET_SIZE = 48;
private static final int NTP_PORT = 123;
private static final int NTP_MODE_CLIENT = 3;
private static final int NTP_VERSION = 3;
// Number of seconds between Jan 1, 1900 and Jan 1, 1970
// 70 years plus 17 leap days
private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;
private long mNtpTime;
public boolean requestTime(String host, int timeout) {
try {
DatagramSocket socket = new DatagramSocket();
socket.setSoTimeout(timeout);
InetAddress address = InetAddress.getByName(host);
byte[] buffer = new byte[NTP_PACKET_SIZE];
DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);
buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);
writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET);
socket.send(request);
// read the response
DatagramPacket response = new DatagramPacket(buffer, buffer.length);
socket.receive(response);
socket.close();
mNtpTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);
} catch (Exception e) {
// if (Config.LOGD) Log.d(TAG, "request time failed: " + e);
return false;
}
return true;
}
public long getNtpTime() {
return mNtpTime;
}
/**
* Reads an unsigned 32 bit big endian number from the given offset in the buffer.
*/
private long read32(byte[] buffer, int offset) {
byte b0 = buffer[offset];
byte b1 = buffer[offset+1];
byte b2 = buffer[offset+2];
byte b3 = buffer[offset+3];
// convert signed bytes to unsigned values
int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);
return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
}
/**
* Reads the NTP time stamp at the given offset in the buffer and returns
* it as a system time (milliseconds since January 1, 1970).
*/
private long readTimeStamp(byte[] buffer, int offset) {
long seconds = read32(buffer, offset);
long fraction = read32(buffer, offset + 4);
return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);
}
/**
* Writes 0 as NTP starttime stamp in the buffer. --> Then NTP returns Time OFFSET since 1900
*/
private void writeTimeStamp(byte[] buffer, int offset) {
int ofs = offset++;
for (int i=ofs;i<(ofs+8);i++)
buffer[i] = (byte)(0);
}
}
And use it with:
long now = 0;
NTP_UTC_Time client = new NTP_UTC_Time();
if (client.requestTime("pool.ntp.org", 2000)) {
now = client.getNtpTime();
}
If you need UTC Time "now" as DateTimeString use function:
private String get_UTC_Datetime_from_timestamp(long timeStamp){
try{
Calendar cal = Calendar.getInstance();
TimeZone tz = cal.getTimeZone();
int tzt = tz.getOffset(System.currentTimeMillis());
timeStamp -= tzt;
// DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.getDefault());
DateFormat sdf = new SimpleDateFormat();
Date netDate = (new Date(timeStamp));
return sdf.format(netDate);
}
catch(Exception ex){
return "";
}
}
and use it with:
String UTC_DateTime = get_UTC_Datetime_from_timestamp(now);
With:
Calendar cal = Calendar.getInstance();
Then cal have the current date and time.
You also could get the current Date and Time for timezone with:
Calendar cal2 = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));
You could ask cal.get(Calendar.DATE); or other Calendar constant about others details.
Date and Timestamp are deprecated in Java. Calendar class it isn't.
If you want a Date object with fields adjusted for UTC you can do it like this with Joda Time:
import org.joda.time.DateTimeZone;
import java.util.Date;
...
Date local = new Date();
System.out.println("Local: " + local);
DateTimeZone zone = DateTimeZone.getDefault();
long utc = zone.convertLocalToUTC(local.getTime(), false);
System.out.println("UTC: " + new Date(utc));
This works for getting UTC milliseconds in Android.
Calendar c = Calendar.getInstance();
int utcOffset = c.get(Calendar.ZONE_OFFSET) + c.get(Calendar.DST_OFFSET);
Long utcMilliseconds = c.getTimeInMillis() + utcOffset;
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
//Local time zone
SimpleDateFormat dateFormatLocal = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
//Time in GMT
return dateFormatLocal.parse( dateFormatGmt.format(new Date()) );
If you're using joda time and want the current time in milliseconds without your local offset you can use this:
long instant = DateTimeZone.UTC.getMillisKeepLocal(DateTimeZone.getDefault(), System.currentTimeMillis());
public class CurrentUtcDate
{
public static void main(String[] args) {
Date date = new Date();
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println("UTC Time is: " + dateFormat.format(date));
}
}
Output:
UTC Time is: 22-01-2018 13:14:35
You can change the date format as needed.
If you're using joda time and want the current time in milliseconds without your local offset you can use this:
long instant = DateTimeZone.UTC.getMillisKeepLocal(DateTimeZone.getDefault(), System.currentTimeMillis());
Here an other suggestion to get a GMT Timestamp object:
import java.sql.Timestamp;
import java.util.Calendar;
...
private static Timestamp getGMT() {
Calendar cal = Calendar.getInstance();
return new Timestamp(cal.getTimeInMillis()
-cal.get(Calendar.ZONE_OFFSET)
-cal.get(Calendar.DST_OFFSET));
}
Use java.time package and include below code-
ZonedDateTime now = ZonedDateTime.now( ZoneOffset.UTC );
or
LocalDateTime now2 = LocalDateTime.now( ZoneOffset.UTC );
depending on your application need.
To put it simple. A calendar object stores information about time zone but when you perform cal.getTime() then the timezone information will be lost. So for Timezone conversions I will advice to use DateFormat classes...
Here is what seems to be incorrect in Jon Skeet's answer. He said:
java.util.Dateis always in UTC. What makes you think it's in local time? I suspect the problem is that you're displaying it via an instance of Calendar which uses the local timezone, or possibly usingDate.toString()which also uses the local timezone.
However, the code:
System.out.println(new java.util.Date().getHours() + " hours");
gives the local hours, not GMT (UTC hours), using no Calendar and no SimpleDateFormat at all.
That is why is seems something is incorrect.
Putting together the responses, the code:
System.out.println(Calendar.getInstance(TimeZone.getTimeZone("GMT"))
.get(Calendar.HOUR_OF_DAY) + " Hours");
shows the GMT hours instead of the local hours -- note that getTime.getHours() is missing because that would create a Date() object, which theoretically stores the date in GMT, but gives back the hours in the local time zone.
This definitely returns UTC time: as String and Date objects !
static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
public static Date getUTCdatetimeAsDate() {
// note: doesn't check for null
return stringDateToDate(getUTCdatetimeAsString());
}
public static String getUTCdatetimeAsString() {
final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
final String utcTime = sdf.format(new Date());
return utcTime;
}
public static Date stringDateToDate(String StrDate) {
Date dateToReturn = null;
SimpleDateFormat dateFormat = new SimpleDateFormat(DATEFORMAT);
try {
dateToReturn = (Date)dateFormat.parse(StrDate);
}
catch (ParseException e) {
e.printStackTrace();
}
return dateToReturn;
}
Converting Current DateTime in UTC:
DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
DateTimeZone dateTimeZone = DateTimeZone.getDefault(); //Default Time Zone
DateTime currDateTime = new DateTime(); //Current DateTime
long utcTime = dateTimeZone.convertLocalToUTC(currDateTime .getMillis(), false);
String currTime = formatter.print(utcTime); //UTC time converted to string from long in format of formatter
currDateTime = formatter.parseDateTime(currTime); //Converted to DateTime in UTC
You can directly use this
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("dd:MM:yyyy HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(dateFormatGmt.format(new Date())+"");
Use java.time package and include below code-
ZonedDateTime now = ZonedDateTime.now( ZoneOffset.UTC );
or
LocalDateTime now2 = LocalDateTime.now( ZoneOffset.UTC );
depending on your application need.
Calendar c = Calendar.getInstance();
System.out.println("current: "+c.getTime());
TimeZone z = c.getTimeZone();
int offset = z.getRawOffset();
if(z.inDaylightTime(new Date())){
offset = offset + z.getDSTSavings();
}
int offsetHrs = offset / 1000 / 60 / 60;
int offsetMins = offset / 1000 / 60 % 60;
System.out.println("offset: " + offsetHrs);
System.out.println("offset: " + offsetMins);
c.add(Calendar.HOUR_OF_DAY, (-offsetHrs));
c.add(Calendar.MINUTE, (-offsetMins));
System.out.println("GMT Time: "+c.getTime());
With:
Calendar cal = Calendar.getInstance();
Then cal have the current date and time.
You also could get the current Date and Time for timezone with:
Calendar cal2 = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));
You could ask cal.get(Calendar.DATE); or other Calendar constant about others details.
Date and Timestamp are deprecated in Java. Calendar class it isn't.
public static void main(String args[]){
LocalDate date=LocalDate.now();
System.out.println("Current date = "+date);
}
This works for getting UTC milliseconds in Android.
Calendar c = Calendar.getInstance();
int utcOffset = c.get(Calendar.ZONE_OFFSET) + c.get(Calendar.DST_OFFSET);
Long utcMilliseconds = c.getTimeInMillis() + utcOffset;
Sample code to render system time in a specific time zone and a specific format.
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
public class TimZoneTest {
public static void main (String[] args){
//<GMT><+/-><hour>:<minutes>
// Any screw up in this format, timezone defaults to GMT QUIETLY. So test your format a few times.
System.out.println(my_time_in("GMT-5:00", "MM/dd/yyyy HH:mm:ss") );
System.out.println(my_time_in("GMT+5:30", "'at' HH:mm a z 'on' MM/dd/yyyy"));
System.out.println("---------------------------------------------");
// Alternate format
System.out.println(my_time_in("America/Los_Angeles", "'at' HH:mm a z 'on' MM/dd/yyyy") );
System.out.println(my_time_in("America/Buenos_Aires", "'at' HH:mm a z 'on' MM/dd/yyyy") );
}
public static String my_time_in(String target_time_zone, String format){
TimeZone tz = TimeZone.getTimeZone(target_time_zone);
Date date = Calendar.getInstance().getTime();
SimpleDateFormat date_format_gmt = new SimpleDateFormat(format);
date_format_gmt.setTimeZone(tz);
return date_format_gmt.format(date);
}
}
Output
10/08/2011 21:07:21
at 07:37 AM GMT+05:30 on 10/09/2011
at 19:07 PM PDT on 10/08/2011
at 23:07 PM ART on 10/08/2011
You can directly use this
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("dd:MM:yyyy HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(dateFormatGmt.format(new Date())+"");
public static void main(String args[]){
LocalDate date=LocalDate.now();
System.out.println("Current date = "+date);
}
Actually not time, but it's representation could be changed.
SimpleDateFormat f = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
f.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(f.format(new Date()));
Time is the same in any point of the Earth, but our perception of time could be different depending on location.
this is my implementation:
public static String GetCurrentTimeStamp()
{
Calendar cal=Calendar.getInstance();
long offset = cal.getTimeZone().getOffset(System.currentTimeMillis());//if you want in UTC else remove it .
return new java.sql.Timestamp(System.currentTimeMillis()+offset).toString();
}
Here an other suggestion to get a GMT Timestamp object:
import java.sql.Timestamp;
import java.util.Calendar;
...
private static Timestamp getGMT() {
Calendar cal = Calendar.getInstance();
return new Timestamp(cal.getTimeInMillis()
-cal.get(Calendar.ZONE_OFFSET)
-cal.get(Calendar.DST_OFFSET));
}
Use this Class to get ever the right UTC Time from a Online NTP Server:
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
class NTP_UTC_Time
{
private static final String TAG = "SntpClient";
private static final int RECEIVE_TIME_OFFSET = 32;
private static final int TRANSMIT_TIME_OFFSET = 40;
private static final int NTP_PACKET_SIZE = 48;
private static final int NTP_PORT = 123;
private static final int NTP_MODE_CLIENT = 3;
private static final int NTP_VERSION = 3;
// Number of seconds between Jan 1, 1900 and Jan 1, 1970
// 70 years plus 17 leap days
private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;
private long mNtpTime;
public boolean requestTime(String host, int timeout) {
try {
DatagramSocket socket = new DatagramSocket();
socket.setSoTimeout(timeout);
InetAddress address = InetAddress.getByName(host);
byte[] buffer = new byte[NTP_PACKET_SIZE];
DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);
buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);
writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET);
socket.send(request);
// read the response
DatagramPacket response = new DatagramPacket(buffer, buffer.length);
socket.receive(response);
socket.close();
mNtpTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);
} catch (Exception e) {
// if (Config.LOGD) Log.d(TAG, "request time failed: " + e);
return false;
}
return true;
}
public long getNtpTime() {
return mNtpTime;
}
/**
* Reads an unsigned 32 bit big endian number from the given offset in the buffer.
*/
private long read32(byte[] buffer, int offset) {
byte b0 = buffer[offset];
byte b1 = buffer[offset+1];
byte b2 = buffer[offset+2];
byte b3 = buffer[offset+3];
// convert signed bytes to unsigned values
int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);
return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
}
/**
* Reads the NTP time stamp at the given offset in the buffer and returns
* it as a system time (milliseconds since January 1, 1970).
*/
private long readTimeStamp(byte[] buffer, int offset) {
long seconds = read32(buffer, offset);
long fraction = read32(buffer, offset + 4);
return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);
}
/**
* Writes 0 as NTP starttime stamp in the buffer. --> Then NTP returns Time OFFSET since 1900
*/
private void writeTimeStamp(byte[] buffer, int offset) {
int ofs = offset++;
for (int i=ofs;i<(ofs+8);i++)
buffer[i] = (byte)(0);
}
}
And use it with:
long now = 0;
NTP_UTC_Time client = new NTP_UTC_Time();
if (client.requestTime("pool.ntp.org", 2000)) {
now = client.getNtpTime();
}
If you need UTC Time "now" as DateTimeString use function:
private String get_UTC_Datetime_from_timestamp(long timeStamp){
try{
Calendar cal = Calendar.getInstance();
TimeZone tz = cal.getTimeZone();
int tzt = tz.getOffset(System.currentTimeMillis());
timeStamp -= tzt;
// DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.getDefault());
DateFormat sdf = new SimpleDateFormat();
Date netDate = (new Date(timeStamp));
return sdf.format(netDate);
}
catch(Exception ex){
return "";
}
}
and use it with:
String UTC_DateTime = get_UTC_Datetime_from_timestamp(now);
If you want to avoid parsing the date and just want a timestamp in GMT, you could use:
final Date gmt = new Timestamp(System.currentTimeMillis()
- Calendar.getInstance().getTimeZone()
.getOffset(System.currentTimeMillis()));
tl;dr
Instant.now() // Capture the current moment in UTC.
Generate a String to represent that value:
Instant.now().toString()
2016-09-13T23:30:52.123Z
Details
As the correct answer by Jon Skeet stated, a java.util.Date object has no time zone†. But its toString implementation applies the JVM’s default time zone when generating the String representation of that date-time value. Confusingly to the naïve programmer, a Date seems to have a time zone but does not.
The java.util.Date, j.u.Calendar, and java.text.SimpleDateFormat classes bundled with Java are notoriously troublesome. Avoid them. Instead, use either of these competent date-time libraries:
- java.time.* package in Java 8
- Joda-Time
java.time (Java 8)
Java 8 brings an excellent new java.time.* package to supplant the old java.util.Date/Calendar classes.
Getting current time in UTC/GMT is a simple one-liner…
Instant instant = Instant.now();
That Instant class is the basic building block in java.time, representing a moment on the timeline in UTC with a resolution of nanoseconds.
In Java 8, the current moment is captured with only up to milliseconds resolution. Java 9 brings a fresh implementation of Clock captures the current moment in up to the full nanosecond capability of this class, depending on the ability of your host computer’s clock hardware.
It’s toString method generates a String representation of its value using one specific ISO 8601 format. That format outputs zero, three, six or nine digits digits (milliseconds, microseconds, or nanoseconds) as necessary to represent the fraction-of-second.
If you want more flexible formatting, or other additional features, then apply an offset-from-UTC of zero, for UTC itself (ZoneOffset.UTC constant) to get a OffsetDateTime.
OffsetDateTime now = OffsetDateTime.now( ZoneOffset.UTC );
Dump to console…
System.out.println( "now.toString(): " + now );
When run…
now.toString(): 2014-01-21T23:42:03.522Z
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
- Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
- Java 9 adds some minor features and fixes.
- Java SE 6 and Java SE 7
- Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
- Android
- Later versions of Android bundle implementations of the java.time classes.
- For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.
Joda-Time
UPDATE: The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
Using the Joda-Time 3rd-party open-source free-of-cost library, you can get the current date-time in just one line of code.
Joda-Time inspired the new java.time.* classes in Java 8, but has a different architecture. You may use Joda-Time in older versions of Java. Joda-Time continues to work in Java 8 and continues to be actively maintained (as of 2014). However, the Joda-Time team does advise migration to java.time.
System.out.println( "UTC/GMT date-time in ISO 8601 format: " + new org.joda.time.DateTime( org.joda.time.DateTimeZone.UTC ) );
More detailed example code (Joda-Time 2.3)…
org.joda.time.DateTime now = new org.joda.time.DateTime(); // Default time zone.
org.joda.time.DateTime zulu = now.toDateTime( org.joda.time.DateTimeZone.UTC );
Dump to console…
System.out.println( "Local time in ISO 8601 format: " + now );
System.out.println( "Same moment in UTC (Zulu): " + zulu );
When run…
Local time in ISO 8601 format: 2014-01-21T15:34:29.933-08:00
Same moment in UTC (Zulu): 2014-01-21T23:34:29.933Z
For more example code doing time zone work, see my answer to a similar question.
Time Zone
I recommend you always specify a time zone rather than relying implicitly on the JVM’s current default time zone (which can change at any moment!). Such reliance seems to be a common cause of confusion and bugs in date-time work.
When calling now() pass the desired/expected time zone to be assigned. Use the DateTimeZone class.
DateTimeZone zoneMontréal = DateTimeZone.forID( "America/Montreal" );
DateTime now = DateTime.now( zoneMontréal );
That class holds a constant for UTC time zone.
DateTime now = DateTime.now( DateTimeZone.UTC );
If you truly want to use the JVM’s current default time zone, make an explicit call so your code is self-documenting.
DateTimeZone zoneDefault = DateTimeZone.getDefault();
ISO 8601
Read about ISO 8601 formats. Both java.time and Joda-Time use that standard’s sensible formats as their defaults for both parsing and generating strings.
† Actually, java.util.Date does have a time zone, buried deep under layers of source code. For most practical purposes, that time zone is ignored. So, as shorthand, we say java.util.Date has no time zone. Furthermore, that buried time zone is not the one used by Date’s toString method; that method uses the JVM’s current default time zone. All the more reason to avoid this confusing class and stick with Joda-Time and java.time.
Current date in the UTC
Instant.now().toString().replaceAll("T.*", "");
tl;dr
Instant.now() // Capture the current moment in UTC.
Generate a String to represent that value:
Instant.now().toString()
2016-09-13T23:30:52.123Z
Details
As the correct answer by Jon Skeet stated, a java.util.Date object has no time zone†. But its toString implementation applies the JVM’s default time zone when generating the String representation of that date-time value. Confusingly to the naïve programmer, a Date seems to have a time zone but does not.
The java.util.Date, j.u.Calendar, and java.text.SimpleDateFormat classes bundled with Java are notoriously troublesome. Avoid them. Instead, use either of these competent date-time libraries:
- java.time.* package in Java 8
- Joda-Time
java.time (Java 8)
Java 8 brings an excellent new java.time.* package to supplant the old java.util.Date/Calendar classes.
Getting current time in UTC/GMT is a simple one-liner…
Instant instant = Instant.now();
That Instant class is the basic building block in java.time, representing a moment on the timeline in UTC with a resolution of nanoseconds.
In Java 8, the current moment is captured with only up to milliseconds resolution. Java 9 brings a fresh implementation of Clock captures the current moment in up to the full nanosecond capability of this class, depending on the ability of your host computer’s clock hardware.
It’s toString method generates a String representation of its value using one specific ISO 8601 format. That format outputs zero, three, six or nine digits digits (milliseconds, microseconds, or nanoseconds) as necessary to represent the fraction-of-second.
If you want more flexible formatting, or other additional features, then apply an offset-from-UTC of zero, for UTC itself (ZoneOffset.UTC constant) to get a OffsetDateTime.
OffsetDateTime now = OffsetDateTime.now( ZoneOffset.UTC );
Dump to console…
System.out.println( "now.toString(): " + now );
When run…
now.toString(): 2014-01-21T23:42:03.522Z
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
- Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
- Java 9 adds some minor features and fixes.
- Java SE 6 and Java SE 7
- Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
- Android
- Later versions of Android bundle implementations of the java.time classes.
- For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.
Joda-Time
UPDATE: The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
Using the Joda-Time 3rd-party open-source free-of-cost library, you can get the current date-time in just one line of code.
Joda-Time inspired the new java.time.* classes in Java 8, but has a different architecture. You may use Joda-Time in older versions of Java. Joda-Time continues to work in Java 8 and continues to be actively maintained (as of 2014). However, the Joda-Time team does advise migration to java.time.
System.out.println( "UTC/GMT date-time in ISO 8601 format: " + new org.joda.time.DateTime( org.joda.time.DateTimeZone.UTC ) );
More detailed example code (Joda-Time 2.3)…
org.joda.time.DateTime now = new org.joda.time.DateTime(); // Default time zone.
org.joda.time.DateTime zulu = now.toDateTime( org.joda.time.DateTimeZone.UTC );
Dump to console…
System.out.println( "Local time in ISO 8601 format: " + now );
System.out.println( "Same moment in UTC (Zulu): " + zulu );
When run…
Local time in ISO 8601 format: 2014-01-21T15:34:29.933-08:00
Same moment in UTC (Zulu): 2014-01-21T23:34:29.933Z
For more example code doing time zone work, see my answer to a similar question.
Time Zone
I recommend you always specify a time zone rather than relying implicitly on the JVM’s current default time zone (which can change at any moment!). Such reliance seems to be a common cause of confusion and bugs in date-time work.
When calling now() pass the desired/expected time zone to be assigned. Use the DateTimeZone class.
DateTimeZone zoneMontréal = DateTimeZone.forID( "America/Montreal" );
DateTime now = DateTime.now( zoneMontréal );
That class holds a constant for UTC time zone.
DateTime now = DateTime.now( DateTimeZone.UTC );
If you truly want to use the JVM’s current default time zone, make an explicit call so your code is self-documenting.
DateTimeZone zoneDefault = DateTimeZone.getDefault();
ISO 8601
Read about ISO 8601 formats. Both java.time and Joda-Time use that standard’s sensible formats as their defaults for both parsing and generating strings.
† Actually, java.util.Date does have a time zone, buried deep under layers of source code. For most practical purposes, that time zone is ignored. So, as shorthand, we say java.util.Date has no time zone. Furthermore, that buried time zone is not the one used by Date’s toString method; that method uses the JVM’s current default time zone. All the more reason to avoid this confusing class and stick with Joda-Time and java.time.
You can use:
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
Then all operations performed using the aGMTCalendar object will be done with the GMT time zone and will not have the daylight savings time or fixed offsets applied. I think the previous poster is correct that the Date() object always returns a GMT it's not until you go to do something with the date object that it gets converted to the local time zone.
Here is another way to get GMT time in String format
String DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss z" ;
final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
String dateTimeString = sdf.format(new Date());
Current date in the UTC
Instant.now().toString().replaceAll("T.*", "");
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT")); Then all operations performed using the aGMTCalendar object will be done with the GMT time zone and will not have the daylight savings time or fixed offsets applied
Wrong!
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
aGMTCalendar.getTime(); //or getTimeInMillis()
and
Calendar aNotGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));aNotGMTCalendar.getTime();
will return the same time. Idem for
new Date(); //it's not GMT.
Converting Current DateTime in UTC:
DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
DateTimeZone dateTimeZone = DateTimeZone.getDefault(); //Default Time Zone
DateTime currDateTime = new DateTime(); //Current DateTime
long utcTime = dateTimeZone.convertLocalToUTC(currDateTime .getMillis(), false);
String currTime = formatter.print(utcTime); //UTC time converted to string from long in format of formatter
currDateTime = formatter.parseDateTime(currTime); //Converted to DateTime in UTC
Sample code to render system time in a specific time zone and a specific format.
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
public class TimZoneTest {
public static void main (String[] args){
//<GMT><+/-><hour>:<minutes>
// Any screw up in this format, timezone defaults to GMT QUIETLY. So test your format a few times.
System.out.println(my_time_in("GMT-5:00", "MM/dd/yyyy HH:mm:ss") );
System.out.println(my_time_in("GMT+5:30", "'at' HH:mm a z 'on' MM/dd/yyyy"));
System.out.println("---------------------------------------------");
// Alternate format
System.out.println(my_time_in("America/Los_Angeles", "'at' HH:mm a z 'on' MM/dd/yyyy") );
System.out.println(my_time_in("America/Buenos_Aires", "'at' HH:mm a z 'on' MM/dd/yyyy") );
}
public static String my_time_in(String target_time_zone, String format){
TimeZone tz = TimeZone.getTimeZone(target_time_zone);
Date date = Calendar.getInstance().getTime();
SimpleDateFormat date_format_gmt = new SimpleDateFormat(format);
date_format_gmt.setTimeZone(tz);
return date_format_gmt.format(date);
}
}
Output
10/08/2011 21:07:21
at 07:37 AM GMT+05:30 on 10/09/2011
at 19:07 PM PDT on 10/08/2011
at 23:07 PM ART on 10/08/2011
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
//Local time zone
SimpleDateFormat dateFormatLocal = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
//Time in GMT
return dateFormatLocal.parse( dateFormatGmt.format(new Date()) );
Here is my implementation of toUTC:
public static Date toUTC(Date date){
long datems = date.getTime();
long timezoneoffset = TimeZone.getDefault().getOffset(datems);
datems -= timezoneoffset;
return new Date(datems);
}
There's probably several ways to improve it, but it works for me.
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MM-dd");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(dateFormatGmt.format(date));
You can use:
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
Then all operations performed using the aGMTCalendar object will be done with the GMT time zone and will not have the daylight savings time or fixed offsets applied. I think the previous poster is correct that the Date() object always returns a GMT it's not until you go to do something with the date object that it gets converted to the local time zone.
Calendar c = Calendar.getInstance();
System.out.println("current: "+c.getTime());
TimeZone z = c.getTimeZone();
int offset = z.getRawOffset();
if(z.inDaylightTime(new Date())){
offset = offset + z.getDSTSavings();
}
int offsetHrs = offset / 1000 / 60 / 60;
int offsetMins = offset / 1000 / 60 % 60;
System.out.println("offset: " + offsetHrs);
System.out.println("offset: " + offsetMins);
c.add(Calendar.HOUR_OF_DAY, (-offsetHrs));
c.add(Calendar.MINUTE, (-offsetMins));
System.out.println("GMT Time: "+c.getTime());
This code prints the current time UTC.
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class Test
{
public static void main(final String[] args) throws ParseException
{
final SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
f.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(f.format(new Date()));
}
}
Result
2013-10-26 14:37:48 UTC
If you want a Date object with fields adjusted for UTC you can do it like this with Joda Time:
import org.joda.time.DateTimeZone;
import java.util.Date;
...
Date local = new Date();
System.out.println("Local: " + local);
DateTimeZone zone = DateTimeZone.getDefault();
long utc = zone.convertLocalToUTC(local.getTime(), false);
System.out.println("UTC: " + new Date(utc));
With:
Calendar cal = Calendar.getInstance();
Then cal have the current date and time.
You also could get the current Date and Time for timezone with:
Calendar cal2 = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));
You could ask cal.get(Calendar.DATE); or other Calendar constant about others details.
Date and Timestamp are deprecated in Java. Calendar class it isn't.
public class CurrentUtcDate
{
public static void main(String[] args) {
Date date = new Date();
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println("UTC Time is: " + dateFormat.format(date));
}
}
Output:
UTC Time is: 22-01-2018 13:14:35
You can change the date format as needed.
Just to make this simpler, to create a Date in UTC you can use Calendar :
Calendar.getInstance(TimeZone.getTimeZone("UTC"));
Which will construct a new instance for Calendar using the "UTC" TimeZone.
If you need a Date object from that calendar you could just use getTime().
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT")); Then all operations performed using the aGMTCalendar object will be done with the GMT time zone and will not have the daylight savings time or fixed offsets applied
Wrong!
Calendar aGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
aGMTCalendar.getTime(); //or getTimeInMillis()
and
Calendar aNotGMTCalendar = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));aNotGMTCalendar.getTime();
will return the same time. Idem for
new Date(); //it's not GMT.
Here is another way to get GMT time in String format
String DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss z" ;
final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
String dateTimeString = sdf.format(new Date());
If you want to avoid parsing the date and just want a timestamp in GMT, you could use:
final Date gmt = new Timestamp(System.currentTimeMillis()
- Calendar.getInstance().getTimeZone()
.getOffset(System.currentTimeMillis()));
To put it simple. A calendar object stores information about time zone but when you perform cal.getTime() then the timezone information will be lost. So for Timezone conversions I will advice to use DateFormat classes...
With:
Calendar cal = Calendar.getInstance();
Then cal have the current date and time.
You also could get the current Date and Time for timezone with:
Calendar cal2 = Calendar.getInstance(TimeZone.getTimeZone("GMT-2"));
You could ask cal.get(Calendar.DATE); or other Calendar constant about others details.
Date and Timestamp are deprecated in Java. Calendar class it isn't.
This worked for me, returns the timestamp in GMT!
Date currDate;
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
SimpleDateFormat dateFormatLocal = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
long currTime = 0;
try {
currDate = dateFormatLocal.parse( dateFormatGmt.format(new Date()) );
currTime = currDate.getTime();
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Here is what seems to be incorrect in Jon Skeet's answer. He said:
java.util.Dateis always in UTC. What makes you think it's in local time? I suspect the problem is that you're displaying it via an instance of Calendar which uses the local timezone, or possibly usingDate.toString()which also uses the local timezone.
However, the code:
System.out.println(new java.util.Date().getHours() + " hours");
gives the local hours, not GMT (UTC hours), using no Calendar and no SimpleDateFormat at all.
That is why is seems something is incorrect.
Putting together the responses, the code:
System.out.println(Calendar.getInstance(TimeZone.getTimeZone("GMT"))
.get(Calendar.HOUR_OF_DAY) + " Hours");
shows the GMT hours instead of the local hours -- note that getTime.getHours() is missing because that would create a Date() object, which theoretically stores the date in GMT, but gives back the hours in the local time zone.
This definitely returns UTC time: as String and Date objects !
static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
public static Date getUTCdatetimeAsDate() {
// note: doesn't check for null
return stringDateToDate(getUTCdatetimeAsString());
}
public static String getUTCdatetimeAsString() {
final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
final String utcTime = sdf.format(new Date());
return utcTime;
}
public static Date stringDateToDate(String StrDate) {
Date dateToReturn = null;
SimpleDateFormat dateFormat = new SimpleDateFormat(DATEFORMAT);
try {
dateToReturn = (Date)dateFormat.parse(StrDate);
}
catch (ParseException e) {
e.printStackTrace();
}
return dateToReturn;
}
Just to make this simpler, to create a Date in UTC you can use Calendar :
Calendar.getInstance(TimeZone.getTimeZone("UTC"));
Which will construct a new instance for Calendar using the "UTC" TimeZone.
If you need a Date object from that calendar you could just use getTime().
Actually not time, but it's representation could be changed.
SimpleDateFormat f = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
f.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(f.format(new Date()));
Time is the same in any point of the Earth, but our perception of time could be different depending on location.
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MM-dd");
dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(dateFormatGmt.format(date));
Here is my implementation of toUTC:
public static Date toUTC(Date date){
long datems = date.getTime();
long timezoneoffset = TimeZone.getDefault().getOffset(datems);
datems -= timezoneoffset;
return new Date(datems);
}
There's probably several ways to improve it, but it works for me.
this is my implementation:
public static String GetCurrentTimeStamp()
{
Calendar cal=Calendar.getInstance();
long offset = cal.getTimeZone().getOffset(System.currentTimeMillis());//if you want in UTC else remove it .
return new java.sql.Timestamp(System.currentTimeMillis()+offset).toString();
}
This code prints the current time UTC.
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class Test
{
public static void main(final String[] args) throws ParseException
{
final SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
f.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(f.format(new Date()));
}
}
Result
2013-10-26 14:37:48 UTC
Source: Stackoverflow.com