Java String to Date Change Time Zone

Question

I need to change the IST to GMT in given code below :

import java.text.SimpleDateFormat;  
import java.util.Date;  
public class StringToDateExample1 {  
    public static void main(String[] args)throws Exception {  
      String sDate1="31/12/1998";  
      Date date1=new SimpleDateFormat("dd/MM/yyyy").parse(sDate1);  
      System.out.println(sDate1+"\t"+date1);  
    }  
}  

Output :31/12/1998 Thu Dec 31 00:00:00 IST 1998

I need GMT Time please help!!

Answer 1

You have to add time zone in date format 'T':

SimpleDateFormat isoFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
isoFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(sDate1+"\t"+isoFormat.parse("2010-05-23T09:01:02"));

Answer 2

You are using terrible date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310.

Parse input string as a LocalDate .

String input = "31/12/1998" ; 
DateTimeFormatter f =  DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ;
LocalDate ld = LocalDate.parse( input , f ) ;

Apparently you want to represent the first moment of that day in UTC.

OffsetDateTime odt = OffsetDateTime.of( ld , LocalTime.MIN ,  ZoneOffset.UTC ) ;

To generate a string in a custom format, use the DateTimeFormatter class. That has been covered many many times already on Stack Overflow, I'll not cover that part.

Answer 3

The code for this :

String sDate1 = "31/12/1998";
SimpleDateFormat dateformat = new SimpleDateFormat("dd/MM/yyyy");
dateformat.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(sDate1 + "\t" + dateformat.parse(sDate1));

Output :

31/12/1998  Thu Dec 31 05:30:00 IST 1998