I have a Java date object:
Date currentDate = new Date();
This will give the current date and time. Example:
Thu Jan 12 10:17:47 GMT 2012
Instead, I want to get the date, changing it to one hour back so it should give me:
Thu Jan 12 09:17:47 GMT 2012
What would be the best way to do it?
To subtract hours, you need to use the HOUR_OF_DAY constant. Within that, include the number with the negative sign. This would be the hours you want to reduce. All this is done under the Calendar add() method.
The following is an example:
import java.util.Calendar;
public class Example {
public static void main(String[] args) {
Calendar c = Calendar.getInstance();
System.out.println("Date : " + c.getTime());
// 2 hours subtracted
c.add(Calendar.HOUR_OF_DAY, -2);
System.out.println("After subtracting 2 hrs : " + c.getTime());
}
}
Here is the output:
Date : Sun Dec 16 16:28:53 UTC 2018
After subtracting 2 hrs : Sun Dec 16 14:28:53 UTC 2018
Get the time in milliseconds, minus your minutes in milliseconds and convert it to Date. Here you need to objectify one!!!
int minutes = 60;
long currentDateTime = System.currentTimeMillis();
Date currentDate = new Date(currentDateTime - minutes*60*1000);
System.out.println(currentDate);
It worked for me instead using format .To work with time just use parse and toString() methods
String localTime="6:11"; LocalTime localTime = LocalTime.parse(localtime)
LocalTime lt = 6:11; localTime = lt.toString()
Or using the famous Joda Time library:
DateTime dateTime = new DateTime();
dateTime = dateTime.minusHours(1);
Date modifiedDate = dateTime.toDate();
Use Calendar.
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
cal.set(Calendar.HOUR, cal.get(Calendar.HOUR) - 1);
Similar to @Sumit Jain's solution
Date currentDate = new Date(System.currentTimeMillis() - 3600 * 1000);
or
Date currentDate = new Date(System.currentTimeMillis() - TimeUnit.HOURS.toMillis(1));
This can be achieved using java.util.Date. The following code will subtract 1 hour from your date.
Date date = new Date(yourdate in date format);
Date newDate = DateUtils.addHours(date, -1)
Similarly for subtracting 20 seconds from your date
newDate = DateUtils.addSeconds(date, -20)
In UTC:
Instant.now().minus( 1 , ChronoUnit.HOURS )
Or, zoned:
Instant.now()
.atZone( ZoneId.of ( "America/Montreal" ) )
.minusHours( 1 )
Java 8 and later has the new java.time framework built-in.
InstantIf you only care about UTC (GMT), then use the Instant class.
Instant instant = Instant.now ();
Instant instantHourEarlier = instant.minus ( 1 , ChronoUnit.HOURS );
Dump to console.
System.out.println ( "instant: " + instant + " | instantHourEarlier: " + instantHourEarlier );
instant: 2015-10-29T00:37:48.921Z | instantHourEarlier: 2015-10-28T23:37:48.921Z
Note how in this instant happened to skip back to yesterday’s date.
ZonedDateTimeIf you care about a time zone, use the ZonedDateTime class. You can start with an Instant and the assign a time zone, a ZoneId object. This class handles the necessary adjustments for anomalies such as Daylight Saving Time (DST).
Instant instant = Instant.now ();
ZoneId zoneId = ZoneId.of ( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant ( instant , zoneId );
ZonedDateTime zdtHourEarlier = zdt.minus ( 1 , ChronoUnit.HOURS );
Dump to console.
System.out.println ( "instant: " + instant + "\nzdt: " + zdt + "\nzdtHourEarlier: " + zdtHourEarlier );
instant: 2015-10-29T00:50:30.778Z
zdt: 2015-10-28T20:50:30.778-04:00[America/Montreal]
zdtHourEarlier: 2015-10-28T19:50:30.778-04:00[America/Montreal]
The old java.util.Date/.Calendar classes are now outmoded. Avoid them. They are notoriously troublesome and confusing.
When you must use the old classes for operating with old code not yet updated for the java.time types, call the conversion methods. Here is example code going from an Instant or a ZonedDateTime to a java.util.Date.
java.util.Date date = java.util.Date.from( instant );
…or…
java.util.Date date = java.util.Date.from( zdt.toInstant() );
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.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
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?
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.
Just subtract the number of milliseconds in an hour from the date.
currentDate.setTime(currentDate.getTime() - 3600 * 1000));
You can use from bellow code for date and time :
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
//get current date time with Calendar()
Calendar cal = Calendar.getInstance();
System.out.println("Current Date Time : " + dateFormat.format(cal.getTime()));
cal.add(Calendar.DATE, 1);
System.out.println("Add one day to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.MONTH, 1);
System.out.println("Add one month to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.YEAR, 1);
System.out.println("Add one year to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.HOUR, 1);
System.out.println("Add one hour to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.MINUTE, 1);
System.out.println("Add one minute to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.SECOND, 1);
System.out.println("Add one second to current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println("Subtract one day from current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.MONTH, -1);
System.out.println("Subtract one month from current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.YEAR, -1);
System.out.println("Subtract one year from current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.HOUR, -1);
System.out.println("Subtract one hour from current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.MINUTE, -1);
System.out.println("Subtract one minute from current date : " + dateFormat.format(cal.getTime()));
cal = Calendar.getInstance();
cal.add(Calendar.SECOND, -1);
System.out.println("Subtract one second from current date : " + dateFormat.format(cal.getTime()));
Output :
Current Date Time : 2008/12/28 10:24:53
Add one day to current date : 2008/12/29 10:24:53
Add one month to current date : 2009/01/28 10:24:53
Add one year to current date : 2009/12/28 10:24:53
Add one hour to current date : 2008/12/28 11:24:53
Add one minute to current date : 2008/12/28 10:25:53
Add one second to current date : 2008/12/28 10:24:54
Subtract one day from current date : 2008/12/27 10:24:53
Subtract one month from current date : 2008/11/28 10:24:53
Subtract one year from current date : 2007/12/28 10:24:53
Subtract one hour from current date : 2008/12/28 09:24:53
Subtract one minute from current date : 2008/12/28 10:23:53
Subtract one second from current date : 2008/12/28 10:24:52
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If you need just time :
DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
Source: Stackoverflow.com