I have a date from server in the format yyyy-mm-dd HH:mm:ss .I have the current time in millis by System.currentTimeMillis(). I want to compare both dates and see if date received from server is future date and if it is so schedule an alarm for the future date.
so my question how to compare this 2 different format dates and how to get remaining time (future- current) so as to schedule the alarm.
Edit:
I already tried parsing the date in millis but it doesnt return value as same format as System.currentTimeMillis(). so it fails
You can parse the yyyy-mm-dd HH:mm:ss date thanks to DateFormat class (e.g. the SimpleDateFormat class). This operation will return a Date object.
You can also create a Date object from current time in milliseconds.
When you have both objects you can compare them thanks to compareTo method.
For instance the following code:
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date parsed = sdf.parse("2016-03-10 22:05:20");
Date now = new Date(System.currentTimeMillis()); // 2016-03-10 22:06:10
System.out.println(parsed.compareTo(now));
} catch (Exception e) {
e.printStackTrace();
}
will print -1, which means that parsed is before now.
EDIT:
Here it is the code of a simple but useless application that makes use of AlarmManager.
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d("TAG", "From intent: "+getIntent().getStringExtra("MyEXTRA"));
}
#Override
protected void onResume() {
super.onResume();
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
long parsedMillis = sdf.parse("2016-03-10 22:54:30").getTime();
long now = System.currentTimeMillis(); // 22:54:15
if (parsedMillis > now) {
Log.d("TAG", "In the future!");
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
Intent intent = new Intent(this, MyActivity.class);
intent.putExtra("MyEXTRA", "From alarm");
PendingIntent broadcast = PendingIntent.getActivity(this, 0, intent, 0);
am.setExact(AlarmManager.RTC_WAKEUP, parsedMillis, broadcast);
} else {
Log.d("TAG", "In the past...");
}
} catch (Exception e) {
e.printStackTrace();
}
}
In the LogCat you will see:
03-10 22:54:20.925 3946-3946/com.example.myapp D/TAG﹕ From intent: null
03-10 22:54:21.227 3946-3946/com.example.myapp D/TAG﹕ In the future!
03-10 22:54:30.513 3946-3946/com.example.myapp D/TAG﹕ From intent: From alarm
03-10 22:54:30.577 3946-3946/com.example.myapp D/TAG﹕ In the past...
The last line is printed because the alarm causes the activity to be relaunched, hence the onResume will be called another time and System.currentTimeMillis() will be greater than the hardcoded time. As you can see, however, the alarm is correctly fired at the scheduled time.
Moreover you should consider edge cases: if parsedMillis is greater than now by only a few milliseconds, you could set an alarm that will never be fired because it is set in the past. This happens because the OS needs some time to execute your code, so you should check that parsedMillis > now + DELTA, where DELTA is a reasonable amout of time that depends on the code you execute between System.currentTimeMillis() and am.setExact(...).
I recommend you do it using the modern date-time API*.
A simple way to do it using the modern API is to parse the server's date-time string into ZonedDateTime using the server's timezone and convert the resulting object into Instant which you can compare with Instant#now.
Demo:
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
// An arbitrary date for demo
String strDateTime = "2021-05-09 10:20:30";
// Replace JVM's default time zone, ZoneId.systemDefault() with applicable time
// zone e.g. ZoneId.of("America/New_York")
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("u-M-d H:m:s", Locale.ENGLISH)
.withZone(ZoneId.systemDefault());
ZonedDateTime zdt = ZonedDateTime.parse(strDateTime, dtf);
Instant instantServer = zdt.toInstant();
Instant now = Instant.now();
if (instantServer.isBefore(now))
System.out.println("The server time is before the current time.");
else if (instantServer.isAfter(now))
System.out.println("The server time is after the current time.");
else
System.out.println("The server time is the same as the current time.");
}
}
Output when I run it now in my system:
The server time is before the current time.
Learn more about the the modern date-time API* from Trail: Date Time.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.
I am working on a App in which i want to display notification time.
I can display notification time but not able to add time zone in it.
My current location is Pakistan and i want to add GMT+5:00
My code is attached
String currentDateTimeString = DateFormat.getTimeInstance().format(notif.At);
textViewTime.setText(currentDateTimeString);
in this code, notif.At is dateTime variable. I also attached screenshot of my app, i want to ask you , how to add timeZone value in notif.At. Thanks!
Update
You mark time with timezone in order to solve internationalization problem, I understand, right?
If so, I think it could be better to convert your date to UTC date. When you change to another timezone, just convert this UTC Date to local.
public static Date localToUtc(Date localDate) {
return new Date(localDate.getTime()-TimeZone.getDefault().getOffset(localDate.getTime()));
}
public static Date utcToLocal(Date utcDate) {
return new Date(utcDate.getTime()+TimeZone.getDefault().getOffset(utcDate.getTime()));
}
Old answer
If your notif.At is Dateobject, it's a same question actually:
TimeZone tz = TimeZone.getDefault();
Date date = new Date();
final String format = "yyyy-MM-dd HH:mm:ss";
SimpleDateFormat sdf = new SimpleDateFormat(format, Locale.US);
String result = sdf.format(date);
Log.d("Date ", "date: " + result + " " + tz.getDisplayName(false, TimeZone.SHORT));
print:
date: 2015-03-31 18:45:28 GMT+08:00
You can try java.time api;
Instant date = Instant.ofEpochMilli(1549362600000l);
LocalDateTime utc = LocalDateTime.ofInstant(date, ZoneOffset.UTC);
LocalDateTime pst = LocalDateTime.ofInstant(date, ZoneOffset.of("+05:00"));
LocalDateTime is = LocalDateTime.ofInstant(date, ZoneOffset.of("+05:30"));
There are many questions like this on StackOverflow but no one has the answer I need. I have seen these 3 questions:
Get Value Of Day Month form Date Object in Android?
How to get month and day in android?
Get current time and date on Android
From these 3 questions I have learnt that to get date and time, we need to use Calendar. I have visited its documentation page but that is too hard to understand.
Now my question is I want to get current day i.e 12, current month i.e November, current year i.e 2014 and hour, minute, not seconds and AM or PM.
I only know till here:
Calendar c = Calendar.getInstance();
Now what should I do next?
You can customize the format you want using
DateFormat df = new SimpleDateFormat("dd MM yyyy, HH:mm");
String date = df.format(Calendar.getInstance().getTime());
Calendar calander = Calendar.getInstance();
cDay = calander.get(Calendar.DAY_OF_MONTH);
cMonth = calander.get(Calendar.MONTH) + 1;
cYear = calander.get(Calendar.YEAR);
selectedMonth = "" + cMonth;
selectedYear = "" + cYear;
cHour = calander.get(Calendar.HOUR);
cMinute = calander.get(Calendar.MINUTE);
cSecond = calander.get(Calendar.SECOND);
Use SimpleDateFormat to get date and time in desired format :
Calendar c = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("dd,MMMM,YYYY hh,mm,a");
String strDate = sdf.format(c.getTime());
Calendar localCalendar = Calendar.getInstance(TimeZone.getDefault());
Date currentTime = localCalendar.getTime();
int currentDay = localCalendar.get(Calendar.DATE);
int currentMonth = localCalendar.get(Calendar.MONTH) + 1;
int currentYear = localCalendar.get(Calendar.YEAR);
int currentDayOfWeek = localCalendar.get(Calendar.DAY_OF_WEEK);
int currentDayOfMonth = localCalendar.get(Calendar.DAY_OF_MONTH);
int CurrentDayOfYear = localCalendar.get(Calendar.DAY_OF_YEAR);
System.out.println("Current Date and time details in local timezone");
System.out.println("Current Date: " + currentTime);
System.out.println("Current Day: " + currentDay);
System.out.println("Current Month: " + currentMonth);
System.out.println("Current Year: " + currentYear);
System.out.println("Current Day of Week: " + currentDayOfWeek);
System.out.println("Current Day of Month: " + currentDayOfMonth);
System.out.println("Current Day of Year: " + CurrentDayOfYear);
tl;dr
I want to get current day i.e 12, current month i.e November, current year i.e 2014 and hour, minute, not seconds and AM or PM.
ZonedDateTime
.now(
ZoneId.of( "Pacific/Auckland" ) // Or "Asia/India", "Africa/Tunis", etc.
)
.format(
DateTimeFormatter
.ofPattern(
"dd MMMM uuuu HH:mm"
)
.withLocale(
Locale.CANADA_FRENCH // Or `Locale.US`, or `new Locale( "en" , "IN" )` for English language with India culture.
)
)
See this code run live at IdeOne.com.
28 septembre 2019 08:48
java.time
From these 3 questions I have learnt that to get date and time, we need to use Calendar.
Nope.
The Calendar class is terrible, along with Date & SimpleDateFormat and such. These classes were all supplanted years ago by the modern java.time classes defined in JSR 310.
Now my question is I want to get current day i.e 12, current month i.e November, current year i.e 2014 and hour, minute, not seconds and AM or PM.
Determining a date and time-of-day requires a time zone. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.
If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment during runtime(!), so your results may vary. Better to specify your desired/expected time zone explicitly as an argument. If you want to depend on the JVM’s current default time zone, make your intention clear by calling ZoneId.systemDefault(). If critical, confirm the zone with your user.
Specify a proper time zone name in the format of Continent/Region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 2-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId z = ZoneId.of( "Asia/Kolkata" ) ;
Capture the current moment as seen in the wall-clock time used by the people of a certain region (a time zone).
ZonedDateTime zdt = ZonedDateTime.now( z ) ;
If you do not care about the seconds or fractional-second, truncate.
ZonedDateTime zdt = ZonedDateTime.now( z ).truncatedTo( ChronoUnit.MINUTES ) ;
Generate a string in standard ISO 8601 format, wisely extended to append the name of the time zone in square brackets.
String output = zdt.toString() ;
2019-09-28T01:42+05:30[Asia/Kolkata]
Generate a string, automatically localized.
Locale locale = new Locale( "en" , "IN" ) ; // English language, India culture.
DateTimeFormatter f = DateTimeFormatter.ofLocalizedDateTime( FormatStyle.LONG ).withLocale( locale ) ;
String output2 = zdt.format( f ) ;
28 September 2019 at 1:42:00 AM IST
See this code run live at IdeOne.com.
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….
public class XYZ extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);
Calendar c = Calendar.getInstance();
System.out.println("Current time => "+c.getTime());
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String formattedDate = df.format(c.getTime());
// formattedDate have current date/time
Toast.makeText(this, formattedDate, Toast.LENGTH_SHORT).show();
// Now we display formattedDate value in TextView
TextView txtView = new TextView(this);
txtView.setText("Current Date and Time : "+formattedDate);
txtView.setGravity(Gravity.CENTER);
txtView.setTextSize(20);
setContentView(txtView);
}
}
Calendar calander = Calendar.getInstance();
cDay = calander.get(Calendar.DAY_OF_MONTH);
cMonth = calander.get(Calendar.MONTH) + 1;
cYear = calander.get(Calendar.YEAR);
selectedMonth = "" + cMonth;
selectedYear = "" + cYear;
cHour = calander.get(Calendar.HOUR);
cMinute = calander.get(Calendar.MINUTE);
cSecond = calander.get(Calendar.SECOND);
Want to improve this post? Provide detailed answers to this question, including citations and an explanation of why your answer is correct. Answers without enough detail may be edited or deleted.
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?
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.
java.util.Date has no specific time zone, although its value is most commonly thought of in relation to UTC. What makes you think it's in local time?
To be precise: the value within a java.util.Date is the number of milliseconds since the Unix epoch, which occurred at midnight January 1st 1970, UTC. The same epoch could also be described in other time zones, but the traditional description is in terms of UTC. As it's a number of milliseconds since a fixed epoch, the value within java.util.Date is the same around the world at any particular instant, regardless of local time zone.
I suspect the problem is that you're displaying it via an instance of Calendar which uses the local timezone, or possibly using Date.toString() which also uses the local timezone, or a SimpleDateFormat instance, which, by default, also uses local timezone.
If this isn't the problem, please post some sample code.
I would, however, recommend that you use Joda-Time anyway, which offers a much clearer API.
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()) );
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;
}
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());
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 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;
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.
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
Here is what seems to be incorrect in Jon Skeet's answer. He said:
java.util.Date is 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 using
Date.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.
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));
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.
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.
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())+"");
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));
}
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());
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.
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
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().
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
public static void main(String args[]){
LocalDate date=LocalDate.now();
System.out.println("Current date = "+date);
}
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();
}
The Simple Function that you can use:
Edit: this version uses the modern java.time classes.
private static final DateTimeFormatter FORMATTER
= DateTimeFormatter.ofPattern("dd-MM-uuuu HH:mm:ss z");
public static String getUtcDateTime() {
return ZonedDateTime.now(ZoneId.of("Etc/UTC")).format(FORMATTER);
}
Return value from the method:
26-03-2022 17:38:55 UTC
Original function:
public String getUTC_DateTime() {
SimpleDateFormat dateTimeFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss z");
dateTimeFormat.setTimeZone(TimeZone.getTimeZone("UTC"));//gmt
return dateTimeFormat.format(new Date());
}
return of above function:
26-03-2022 08:07:21 UTC
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...
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();
}
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()));
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.
Current date in the UTC
Instant.now().toString().replaceAll("T.*", "");