date time set to calendar with specific time zone not giving correct convert date time of other time zone in java

Question

Here I am giving parameters like month, date, hourofday, seconds like(2,14,11,0), first setting zonevalue (IST).

    Calendar localTime = Calendar.getInstance();
    localTime.setTimeZone(TimeZone.getTimeZone(zoneValue));
    localTime.set(2018, month, date, hourofday,minutes,seconds);

In the below code short name is other time zone, ex: "PST", after setting first calendar to this below calendar I am not getting valid date time related to first calendar parameters.

    Calendar germanyTime = new GregorianCalendar(TimeZone.getTimeZone(shortName));
    germanyTime.setTimeInMillis(localTime.getTimeInMillis());

Our company is still using java 1.6.

Please help me on this, thanks in advance.

Answer 1

Search Stack Overflow before posting. This has been addressed many times already. And read the Oracle Tutorial. So briefly here…

tl;dr

ZonedDateTime.of( 2018 , 1 , 23 , 12 , 34, 56 , 0 , ZoneId.of( “Asia/Kolkata” ) ) 
    .withZoneSameInstant( ZoneId.of( “Europe/Berlin” ) ) 

java.time

Use modern java.time classes that supplanted the troublesome legacy date-time classes you used.

ZonedDateTime

Pass those arguments to ZonedDateTime.of rather than legacy Calendar.

ZoneId

For the time zone, pass ZoneId object, not legacy TimeZone.

Never use 3-4 letter pseudo-zones like “PST” and “CST” and “IST”. Always use proper time zone names in continent/region format such as America/Los_Angeles or Africa/Tunis.

ZonedDateTime zdt = ZonedDateTime.of( 2018 , 1 , 23 , 12 , 34, 56 , 0 , ZoneId.of( “Asia/Kolkata” ) ) ;

Adjust into another zone. Same moment, same point on the timeline, different wall-clock time.

ZonedDateTime zdt2 = zdt.withZoneSameInstant( ZoneId.of( “Europe/Berlin” ) ) ;

DateTimeFormatter

Generate a String in standard ISO 8601 format by calling ZonedDateTime::toString. For other formats use DateTimeFormatter class.

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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.

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.

Using a JDBC driver compliant with JDBC 4.2 or later, you may exchange java.time objects directly with your database. No need for strings nor java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, and later
  • Built-in.
  • 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
  • Much 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, 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.