Data e orario di conversione in qualche altro timezone in Java

Question

Ho scritto questo codice per convertire la data e l'ora del sistema corrente in qualche altro fuso orario.Non sto ottenendo alcun errore ma non sto ottenendo la mia produzione come previsto.Come se eseguo il mio programma in un determinato momento .. La mia output è:

L'ora corrente in India è: Fri Feb 24 16:09:23 IST 2012

La data e l'ora in :: Tempo standard centrale è: Sat Feb 25 03:39:23 IST 2012

E il tempo effettivo secondo CST fuso orario è:

Friday, 24 February 4:39:16 a.m(GMT - 6:00)

.

Quindi c'è un po 'di Time Gap .E non so perché questo sta accadendo.Qualsiasi aiuto sarà apprezzato .. Il codice è:

package MyPackage;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;

import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

public class Temp2 {


    public static void main(String[] args) {

        try {
            Calendar currentdate = Calendar.getInstance();
            String strdate = null;
            DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
            strdate = formatter.format(currentdate.getTime());
            TimeZone obj = TimeZone.getTimeZone("CST");

            formatter.setTimeZone(obj);
            //System.out.println(strdate);
            //System.out.println(formatter.parse(strdate));
            Date theResult = formatter.parse(strdate);

            System.out.println("The current time in India is  :: " +currentdate.getTime());

            System.out.println("The date and time in :: "+ obj.getDisplayName() + "is ::" + theResult);
        } catch (ParseException e) {
           e.printStackTrace();
        }
    }
}

.

Answer 1

It's over the web. Could have googled. Anyways, here is a version for you (shamelessly picked and modified from here):

Calendar calendar = Calendar.getInstance();
TimeZone fromTimeZone = calendar.getTimeZone();
TimeZone toTimeZone = TimeZone.getTimeZone("CST");

calendar.setTimeZone(fromTimeZone);
calendar.add(Calendar.MILLISECOND, fromTimeZone.getRawOffset() * -1);
if (fromTimeZone.inDaylightTime(calendar.getTime())) {
    calendar.add(Calendar.MILLISECOND, calendar.getTimeZone().getDSTSavings() * -1);
}

calendar.add(Calendar.MILLISECOND, toTimeZone.getRawOffset());
if (toTimeZone.inDaylightTime(calendar.getTime())) {
    calendar.add(Calendar.MILLISECOND, toTimeZone.getDSTSavings());
}

System.out.println(calendar.getTime());

Answer 2

Your mistake is to call parse instead of format.

You call parse to parse a Date from a String, but in your case you've got a Date and need to format it using the correct Timezone.

Replace your code with

Calendar currentdate = Calendar.getInstance();
DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
TimeZone obj = TimeZone.getTimeZone("CST");
formatter.setTimeZone(obj);
System.out.println("Local:: " +currentdate.getTime());
System.out.println("CST:: "+ formatter.format(currentdate.getTime()));

and I hope you'll get the output you are expecting.

Answer 3

Handling dates in Java in my daily work is a non-trivial task. I suggest you to use Joda-Time that simplify our coding days and you don't have to "re-invent the wheel".

Answer 4

You can just use "CST6CDT" because in some countries they follow CDT in summer and CST in winter

 public static String getDateInCST() {
             Calendar calendar = Calendar.getInstance();
             DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
             formatter.setTimeZone(TimeZone.getTimeZone( "CST6CDT"));
             String strdate = formatter.format(calendar.getTime());
             TimeZone.getAvailableIDs();
             return strdate;
     }

Answer 5

Problem is when you print date obj it call toString method and it will print in your machines default time zone. Try this code and see difference.

Calendar currentdate = Calendar.getInstance();
String strdate = null;
DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy HH:mm:ssz");
strdate = formatter.format(currentdate.getTime());
System.out.println("strdate=>" + strdate);
TimeZone obj = TimeZone.getTimeZone("CST");

formatter.setTimeZone(obj);
strdate = formatter.format(currentdate.getTime());
Date theResult = formatter.parse(strdate);

System.out.println("The current time in India is  :: " +currentdate.getTime());

System.out.println("The date and time in :: " + obj.getDisplayName() + "is ::" + theResult);
System.out.println("The date and time in :: " + obj.getDisplayName() + "is ::" + strdate);