CODEWITHSUNDEEP
javadateparsingtimezonesimpledateformat
Radadiya Nikunj
Radadiya Nikunj

Reputation: 1085

Java date parsing has stranger behavior where parsing different date in different timezone

Here I am trying to parse two dates in java. Date 1 is "2021-01-01" and date 2 is "2021-04-01". But after parsing Java generating Date object with a different timezone. Really confused by this behavior. I am looking at the same timezone and that is EDT.

import java.text.DateFormat;
    import java.text.ParseException;
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import java.util.Locale;
    
    
    public class DateCalculation {
    
        private static final DateFormat formater = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
    
        public static void main(String args[]) throws ParseException {
            Date date1 = getDateFromString("2021-01-01");
            System.out.println("Date 1: " + date1);
    
            Date date2 = getDateFromString("2021-04-01");
            System.out.println("Date 2: " + date2);
        }
    
        public static Date getDateFromString(String dateString) throws ParseException {
            if(dateString == null || dateString.trim().length() == 0)
                return null;
    
            dateString = dateString.replace("\"", ""); // Remove quotes
            return formater.parse(dateString);
        }
    }


Output:
Date 1: Fri Jan 01 00:00:00 EST 2021
Date 2: Thu Apr 01 00:00:00 EDT 2021

Upvotes: 0

Views: 77

Answers (1)

Basil Bourque
Basil Bourque

Reputation: 338564

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

LocalDate

For a date-only value without time-of-day and without time zone, use LocalDate class.

LocalDate.parse( "2021-04-01" )

ZonedDateTime

If you want to represent the first moment of the day for that date in a particular time zone, apply ZoneId to get a ZonedDateTime.

Do not assume the day starts at 00:00:00 🕛. Some dates in some zones start at another time such as 01:00:00 🕐. So let java.time determine the first moment.

EDT is not a real time zone. Perhaps you meant America/Montreal, America/New_York, America/Indiana/Marengo, or some such.

LocalDate ld = LocalDate.parse( "2022-01-23" ) ;
ZoneId z = ZoneId.of( "America/Indiana/Marengo" ) ;
ZonedDateTime zdt = ld.atStartOfDay( z ) ;

Upvotes: 2

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