Java does not seem to accept Romance as timezone alias. What should it be?

Question

I'm trying to convert a date string from another application in Groovy. Something like "18-sep-2009 10:25:11 Romance Daylight Time"

It looks like Java does not understand the Romance as timezone alias. "18-sep-2009 10:25:11 Pacific Daylight Time" works fine.

Is there a fix for this other than parse the string and replace "Romance Daylight Time" with the something Java understands? If not, what should it be instead for Europe/Paris timezone?

Answer 1

Try "Central European Time." That's the output of this short program:

import java.util.*;

public class Test
{    
    public static void main(String[] args)
    {
        TimeZone tz = TimeZone.getTimeZone("Europe/Paris");
        System.out.println(tz.getDisplayName());
    }
}

(I feel almost obliged to suggest using Joda Time, but I'm not sure there's enough evidence to suggest it in this case other than on general principle, so I'll just leave this parenthetical comment...)

Answer 2

java.time

The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API^*.

Also, quoted below is a notice from the home page of Joda-Time:

Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.

Solution using java.time, the modern Date-Time API: There are two things that need to be addressed:

1. Change the Date-Time string to have the standard name of the timezone which is Europe/Paris.
2. Build a case-insensitive parser using DateTimeFormatterBuilder.

Demo:

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        String strDateTime = "18-sep-2009 10:25:11 Europe/Paris";
        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                                    .parseCaseInsensitive()
                                    .appendPattern("dd-MMM-uuuu HH:mm:ss zzzz")
                                    .toFormatter(Locale.ENGLISH);
        
        ZonedDateTime zdt = ZonedDateTime.parse(strDateTime, dtf);
        System.out.println(zdt);
    }
}

Output:

2009-09-18T10:25:11+02:00[Europe/Paris]

ONLINE DEMO

However, if changing the Date-Time string is not in your control i.e. you want to go with Romance Daylight Time itself, java.time provides you with a clean way to handle it. All you need to prepare before using java.time API is a Map with all such non-standard timezone names.

Demo:

import java.text.ParsePosition;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.util.Locale;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        String strDateTime = "18-sep-2009 10:25:11 Romance Daylight Time";
        Map<String, String> zoneIdMap = Map.of("Romance Daylight Time", "Europe/Paris");

        DateTimeFormatter dtf = new DateTimeFormatterBuilder()
                                    .parseCaseInsensitive()
                                    .appendPattern("dd-MMM-uuuu HH:mm:ss")
                                    .toFormatter(Locale.ENGLISH);

        ZonedDateTime zdt = LocalDateTime.from(dtf.parse(strDateTime, new ParsePosition(0)))
                                .atZone(ZoneId.of("Romance Daylight Time", zoneIdMap));
        System.out.println(zdt);
    }
}

Output:

2009-09-18T10:25:11+02:00[Europe/Paris]

ONLINE DEMO

Learn more about the modern Date-Time API from Trail: Date Time.

---

^{* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.}